**Rh-Negative Blood:The Ancient Secret Hidden in Human History — Transcript & Summary | SozAI** Source: https://sozai.app/transcript/rh-negative-blood-ancient-secret/ Explore the mystery of Rh-negative blood, its ancient origins, and its puzzling persistence in human populations worldwide. ## Key Takeaways - Rh-negative blood is a rare and ancient genetic trait found in about 15% of humans. - Its uneven global distribution challenges simple evolutionary explanations. - It carries significant reproductive risks but has persisted for tens of thousands of years. - The genetic basis is a deletion rather than a mutation, hinting at a unique evolutionary event. - Understanding Rh-negative blood sheds light on human origins, migration, and genetic diversity. ## What the video covers - Rh-negative blood was discovered in 1940 when some human blood samples did not react to rhesus monkey protein. - About 15% of humans carry Rh-negative blood, which lacks a protein present in most primates and humans. - The distribution of Rh-negative blood is uneven globally, concentrated in populations like the Basque and certain European groups. - Rh-negative blood poses reproductive challenges, causing erythroblastosis fetalis in some pregnancies before modern medicine. - Despite its reproductive risks, Rh-negative blood persists, suggesting a survival advantage or unknown selective pressure. - The Rh-negative gene results from a deletion on chromosome 1, not a mutation, indicating a unique evolutionary origin. - Scientists have dated the mutation to between 35,000 and 40,000 years ago, but its exact origin remains unclear. - The story of Rh-negative blood connects to ancient human history, prehistoric art, royal bloodlines, and isolated populations. - Modern genetic research continues to explore competing theories about why Rh-negative blood has survived natural selection. - The video promises to unfold these mysteries through history, genetics, and anthropology in a detailed narrative. ## Chapters 1. 00:00 Introduction and Discovery of Rh-Negative Blood 2. 09:12 Scientific Theories and Evidence on Rh-Negative Origins 3. 19:07 Medical Implications and Rhogam Treatment 4. 29:11 Genetic Ancestry and Population Distribution 5. 38:57 Historical and Archaeological Contexts 6. 58:50 Evolutionary Significance and Survival of Rh-Negative 7. 68:52 Genomic Studies and Ancient DNA Insights 8. 78:51 Modern Implications and Ongoing Research Answers ## Questions about this video What is Rh-negative blood and how was it discovered? Rh-negative blood is a blood type lacking a specific protein found in most humans and primates. It was discovered in 1940 when scientists noticed some human blood samples did not react to rhesus monkey protein. Why is Rh-negative blood considered a genetic mystery? Rh-negative blood is puzzling because it is unevenly distributed globally, carries reproductive risks, yet has persisted for tens of thousands of years without a clear evolutionary explanation. What are the medical risks associated with Rh-negative blood? Rh-negative mothers carrying Rh-positive babies can develop antibodies that attack the fetus's blood, causing erythroblastosis fetalis, a serious condition that often led to infant death before modern treatments like Rhogam. ## Full Transcript — Download SRT & Markdown 00:00 Speaker A Hey, welcome back. Or if this is your first time here, welcome. Pull your blanket a little closer. Find that one comfortable position you always end up in. And let's just settle in together for a while. Tonight's story is one of 00:13 Speaker A those rare ones that starts inside your own body and somehow ends up thousands of years in the past. Picture this. It is 1940, a laboratory in New York City. 00:24 Speaker A Two scientists, Carl Lansteiner and Alexander Winer, are doing something that sounds almost comically simple. By today's standards, they're injecting a protein found in rhesus monkey blood into a rabbit, watching the rabbit's immune system react, and then carefully, methodically testing whether human blood 00:41 Speaker A reacts the same way. Most of the time it does. The human blood recognizes the protein. It belongs to the same biological family, the same ancient evolutionary tree. Science nods, checks the box, moves on. But then something strange happens. Some of the human blood 00:59 Speaker A samples do not react at all. The protein is introduced and the blood just sits there indifferent, unbothered, as if the protein is speaking a language that this particular blood simply does not understand. Lansteiner and Winer look at each other. They run the test again. 01:18 Speaker A Same result. Again, same result. These people, roughly 15 out of every hundred people they test, are missing something. 01:26 Speaker A Something that every other primate on Earth carries. Something that, as far as anyone can tell, the entire rest of the animal kingdom takes completely for granted. They call it Rhesus negative. 01:38 Speaker A The world will eventually shorten it to Rh negative. And right there in that quiet New York laboratory, a question is born. A question that more than 80 years later, scientists still cannot fully answer. Where did this blood type come 01:52 Speaker A from? And why, against every pressure of natural selection, does it still exist? Before we go any further into this mystery, and I promise you this gets stranger and more beautiful as we go, if you find yourself drawn to this kind of 02:06 Speaker A storytelling, this kind of history that hides in the most unexpected places, take a moment to hit that subscribe button and give this video a like. It genuinely helps more people find their way to stories like this one. And if you 02:21 Speaker A want to leave a comment down below about where you are right now, curled up in bed, winding down after a long day, maybe on the couch with a cup of something warm, I would love to know. 02:31 Speaker A All right, dim the lights just a little more. Maybe turn on a gentle fan in the background. Let the world outside go quiet because this story deserves your full attention. Now, back to that laboratory in 1940. What Lansteiner and 02:46 Speaker A Winer have stumbled onto is not just a quirk of blood chemistry. It is a crack in the story we tell ourselves about human origins. A crack so small that most people never notice it yet, so deep that once you see it, you cannot unsee 03:00 Speaker A it. Here is what makes Rh negative blood genuinely biologically strange. Every human being alive today is thought to descend from the same ancient African ancestors who walked out of Africa roughly 60 to 70,000 years ago. We are one species, one family separated by 03:19 Speaker A time and distance and geography. And yet 15% of humanity is carrying a blood signature that does not match the rest of the family. A signature that, and this is the part that makes geneticists set down their coffee and stare at the 03:35 Speaker A wall, does not appear to have come from anywhere obvious. It is not present in our closest primate relatives at meaningful levels. It is not evenly distributed across the globe. It clusters. It concentrates. It appears in very specific populations in very 03:53 Speaker A specific places and then it nearly vanishes in others. In East Asia, less than 1% of people carry it. In Sub-Saharan Africa, just a handful of isolated populations have it in any significant number. But in the mountains along the 04:09 Speaker A French and Spanish border in a small ancient people called the Basque, the rate climbs as high as 35%. 04:17 Speaker A Among people of northwestern Irish descent, Scottish Highland ancestry, and certain communities along the Atlantic coast of Europe, it hovers between 16 and 25%. 04:29 Speaker A It is, geographically speaking, almost precisely mapped onto the oldest, most isolated corners of the Western world. 04:35 Speaker A Scholars still debate what that pattern actually means. No single explanation fully accounts for it. And that is precisely what makes this blood type one of the most quietly fascinating puzzles in the entire history of human genetics. 04:50 Speaker A Think about what that number means for a moment. 15% of humanity. That is well over a billion people on this planet right now walking around with a blood type whose origins remain genuinely stubbornly unclear. Not mysterious in a 05:06 Speaker A vague hand-waving way. Mysterious in the specific rigorous peer-reviewed scientific sense where researchers have sequenced ancient genomes, dated the mutation to a window somewhere between 35,000 and 40,000 years ago, and still cannot agree on exactly why it survived. 05:25 Speaker A That is a remarkable thing to sit with for a moment. A billion people, an unanswered question, and 80 plus years of looking. Because here is the thing about natural selection. It is ruthless. 05:38 Speaker A It does not keep things around just because they are interesting. If a genetic trait is harmful, truly harmful, in a way that reduces your chances of passing your genes to the next generation, nature tends to quietly phase it out over thousands of years. 05:54 Speaker A And yet Rh negative blood comes with a complication so serious that before modern medicine it killed babies not occasionally, regularly. 06:04 Speaker A When an Rh-negative mother carries an Rh-positive child, her immune system can, under certain conditions, recognize the baby's blood as foreign and begin to attack it. The first pregnancy often proceeds without incident. But the second, the third, each one carries a 06:21 Speaker A higher risk as the mother's immune system grows more sensitized, more efficient at its grim work. Physicians before the 20th century had a name for this pattern, even if they did not understand its cause. They called it erythroblastosis fetalis, a condition 06:36 Speaker A where newborns arrived pale, jaundiced, struggling or not at all. And yet, despite this biological cost, despite the pressure that natural selection places on any trait that threatens reproduction, the Rh negative gene did not disappear. It is still here. It is 06:54 Speaker A still in roughly 15% of the global population. Concentrated, quiet, stubbornly persistent, as if it is waiting for someone to finally understand it. The most widely accepted reconstruction holds that the gene arose from a deletion of a specific section of deoxyribonucleic acid on chromosome 1 which codes for a surface protein on red blood cells simply missing, gone, not mutated into something new, absent. 07:10 Speaker A The gene that builds the rhesus protein in Rh positive people exists in Rh negative people only as a gap, a silence, a place where something used to be or where something was never added in the first place. And that distinction, 07:23 Speaker A deletion versus mutation, matters more than it might seem because a deletion does not usually spread through a population by accident. Something somewhere in some environment that may no longer exist gave the people who carried this gap a reason to survive. 07:38 Speaker A What was that reason? Uh, that is what the next several hours of this story are going to slowly, carefully, beautifully unfold. Because the answer, or rather the several competing answers that scientists and historians and geneticists have been wrestling with, 07:54 Speaker A takes us places you would not expect. It takes us into the painted caves of prehistoric France, where the oldest artists in human history left their handprints on cold stone walls. It takes us into the bloodlines of European royal 08:07 Speaker A families where this very blood type may have quietly shaped the rise and fall of dynasties. It takes us to the mountains of Morocco, to the western shores of Ireland, to laboratories where ancient deoxyribonucleic acid extracted from 10,000-year-old bones is 08:21 Speaker A slowly rewri- 08:39 Speaker A slowly rewriting the map of who we are and where we actually came from. And it takes us to a question that is equal parts science and philosophy. What does it mean to carry something in your blood that the rest of your species does not 08:52 Speaker A share? Is it an accident, an advantage, a remnant of a world that no longer exists? Or, and this is the possibility that keeps certain researchers up at night, is it something older than any of those explanations, something that 09:07 Speaker A points to a branch of the human story that we have only just begun to read? 09:12 Speaker A The evidence, when you look at it closely, is more interesting than the theories. And the theories, even the ones that stretch into speculation, are more grounded than you might think. 09:21 Speaker A There is a place where this story truly begins. Not in a laboratory, not in a history book, but in a stretch of ancient mountains on the border between what is now France and Spain, where a group of people have been living in 09:34 Speaker A quiet, extraordinary isolation for longer than agriculture has existed. Their language has no relatives anywhere on Earth. Their genes carry echoes of a Europe that vanished long before the Romans, long before the Greeks, long before recorded history began. 09:51 Speaker A and their blood, their remarkable anomalous, stubbornly persistent blood may be the oldest continuous thread in the entire human genetic record. That is where we are going next. And I think once you hear what scientists have discovered buried inside those ancient 10:06 Speaker A bones, and what that discovery quietly overturns about everything we assumed we knew, you will understand why this particular mystery has never quite let go of the people who follow it. Some things once seen cannot be unseen. So, let's slow down for just a moment and go 10:22 Speaker A somewhere most people never go when they hear the words blood type. Not into history, not into genetics labs, not into ancient mountain ranges or prehistoric caves. Let's go somewhere much closer to home. Let's go inside the human body. Because before we can truly 10:38 Speaker A understand why Rh negative blood is so strange, we need to understand what it actually does or more precisely what it refuses to do and why that refusal in the wrong circumstances becomes one of the most quietly devastating biological 10:53 Speaker A events a human being can experience. Your immune system at its core is a border patrol. an incredibly sophisticated, deeply loyal, sometimes overzealous border patrol that has been trained since the moment you were conceived to distinguish between two categories of existence, self and not 11:12 Speaker A self. Everything that belongs to your body gets a kind of invisible passport, a molecular marker that says essentially, I am one of us. Let me through. Everything that does not carry that passport is treated as a potential invader. viruses, 11:30 Speaker A bacteria, foreign tissue. The immune system flags these tracks them and builds a memory of them so that the next time they appear, the response is faster, sharper, more precise. It is a remarkable system. Most of the time it 11:46 Speaker A saves your life. But here is where it gets complicated. The reesus protein that surface antigen found on red blood cells in Rh positive people is from the immune systems perspective just another molecular passport stamp. If you are Rh 12:00 Speaker A positive, your body has always known this protein. It is part of you. It does not raise any flags. But if you are Rh negative, your body has never encountered this protein. It has no record of it. And so the first time your 12:14 Speaker A immune system comes into contact with Rh positive blood through a transfusion or through pregnancy, it reacts exactly the way a well-trained border patrol should react to an unrecognized traveler. It says, "I do not know what this is." And 12:29 Speaker A it begins to build a case against it. This process is called sensitization. And the critical word there is first. 12:37 Speaker A Because the first encounter, the first time an Rh negative immune system meets Rh positive blood is usually quiet. The body takes note files. The information away produces a small quantity of what are called anti-D antibodies and waits. 12:53 Speaker A The person might never feel a thing. There is no alarm, no fever, no visible reaction. The immune system has simply made a note in its records. This antigen is foreign and if it ever shows up again, we will be ready. This second 13:06 Speaker A encounter is where everything changes. Now I want you to think about something for a moment. If you are listening to this and you are an RH negative woman or if someone you love is this next part of the story is about you about millions of 13:20 Speaker A women across thousands of years of human history who went through something terrifying without ever understanding what was happening to them or why. And I think it is worth sitting with that before we continue. Imagine a woman, we'll call her Margaret, though she 13:35 Speaker A could have lived in any century, in any country, in any language. Margaret is RH negative, though she does not know this because for most of human history, no one knew blood types existed at all. She has her first child, and the baby is 13:49 Speaker A born healthy. Rosie cheicked, loud, perfect. The pregnancy, by all appearances, went exactly as it should. What Margaret does not know, what no one in her village, her city, her era could possibly know, is that during the final weeks of her 14:06 Speaker A pregnancy, a small amount of her baby's Rh positive blood cross the placental barrier into her bloodstream. It happens in almost every pregnancy to some degree. It is normal. It is expected. 14:21 Speaker A And in her case, it has just quietly activated her immune systems recordeping function. Anti-Dibodies in small numbers have been produced, filed away, waiting. 14:32 Speaker A Margaret's second pregnancy begins. And this time, almost from the moment the fetal blood begins to form tiny Rh positive, perfectly innocent, her immune system recognizes it, not as her child, as an invader. The antid antibodies, now more numerous and more efficient than 14:50 Speaker A before, begin to cross back through the placenta. They attach to the baby's red blood cells. They tag them for destruction. The baby's own body begins to break down its blood supply faster than it can be replaced. Oxygen stops 15:05 Speaker A reaching the organs. The liver swells. The heart strains. The brain deprived of what it needs begins to fail. In the mildest cases, the baby survives but is born severely jaundest, requiring immediate treatment. In moderate cases, the damage is permanent. In the most 15:23 Speaker A severe cases, the pregnancy ends before it begins or the baby arrives into the world already beyond saving. And here is the detail that history rarely bothers to record each subsequent pregnancy made the situation worse. Margaret's third child faced a more aggressive immune 15:39 Speaker A response than the second. Her fourth worse still. The antid- antibodies multiplied with each exposure grew more precise, more relentless. 15:50 Speaker A Some women watched their first child thrive and then lost every child after that one by one without any explanation that medicine of their time could offer. 15:59 Speaker A Midwives noted the pattern and had no framework for it. Physicians classified it under a dozen different names, none of them correct. Religious communities sometimes interpreted repeated infant death as divine punishment as a sign of spiritual impurity as evidence of 16:18 Speaker A something dark in the mother's character or lineage. The cruelty of that misunderstanding is difficult to calculate. We know now thanks to a physician named Philip Lavine who in 1941 published a landmark paper connecting maternal antibodies to infant death exactly what was happening. 16:37 Speaker A Lavine had been investigating a case at Newark's Beth Israel Hospital, a woman who had received a blood transfusion from her own husband and nearly died from the reaction despite the transfusion being of the correct type by every measure then known. The husband's 16:53 Speaker A blood was Rh positive. The wife was Rh negative. Her sensitized immune system rejected it. And in examining her history, Lavine noticed something that had been invisible to everyone before him. She had also lost two previous pregnancies. Infants born pale and 17:12 Speaker A anemic and barely breathing. The connection clicked. The mechanism once understood was devastatingly simple. And yet it had been hiding in plain sight through all of recorded medical history. 17:25 Speaker A The question that naturally follows, and it is a question worth holding for a while, is this. How many women across how many centuries experienced this without ever knowing why? Medical historians have estimated that hemolytic disease of the newborn, which is the 17:42 Speaker A clinical name for what happens when an Rh negative mother's antibodies attack, an Rh positive fetus may have been responsible for a significant percentage of the infant deaths that ancient and medieval societies simply accepted as the unavoidable cost of childbearing. 17:59 Speaker A The numbers are impossible to know with precision, but when you consider that RH negative blood appears in roughly 15% of populations of European descent, and that in many of those same populations, historical infant mortality rates were staggeringly high. Even by the grim 18:17 Speaker A standards of preodern life, the overlap is not nothing. It is something. something that shaped families, shaped inheritance, shaped the quiet arithmetic of who survived and who did not. The evidence remains incomplete as it always does when we try to read medicine 18:32 Speaker A backward through history. But what we can say with confidence is this. For at least 2,000 years, probably longer, a biologically predictable, entirely preventable tragedy was playing out in households across Europe, the Middle East, and North Africa, invisible to 18:49 Speaker A everyone living through it. The fix when it finally arrived was almost absurdly elegant given the scale of the problem it solved. In 1968, 27 years after Lavine identified the mechanism, a drug called RH immunoglobulin was approved for clinical use in the 19:07 Speaker A United States. The trade name most people know it by is rogam. What it does is beautifully simple. introduces preformed antid antibodies into the Rh negative mother's system before her own immune system has a chance to produce them. Those introduced antibodies 19:24 Speaker A neutralize any fetal Rh positive blood cells that have entered her bloodstream, clearing them before sensitization can occur. The immune system never gets the chance to file its case against the foreign antigen. No memory is formed. No antibodies are built. The next pregnancy 19:40 Speaker A begins with a clean slate. The effect on infant mortality in the decades that followed was by any measure extraordinary. A condition that had been silently taking lives for millennia was essentially eliminated in the developed world within a single generation. It is 19:57 Speaker A one of the great quiet victories of 20th century medicine not celebrated nearly as often as it deserves to be. Perhaps because the problem it solved was one that most people had never heard of, and the patients it saved were ones who 20:10 Speaker A never knew they were at risk. But Rogam also did something else, something that nobody fully intended. By making Rh- negative pregnancies safe, it removed the one consistent reproductive pressure that had been quietly working against the survival of the Rh negative gene. 20:27 Speaker A For thousands of years, Rh negative women in populations where AH positive men were common faced a statistical disadvantage in passing their genes forward higher rates of infant loss after the first child's smaller completed family sizes compounding across generations. The introduction of 20:48 Speaker A rogam essentially leveled that playing field overnight. Which raises a question that geneticists find genuinely interesting. What happens to the frequency of the Rh negative gene in human populations now that the biological cost of carrying it has been removed? Is the proportion of Rh 21:04 Speaker A negative people in the world slowly gradually rising? The data is too recent and the time scales too long to say with certainty. But the question itself reveals something important. We have perhaps for the first time in human history altered the selective pressures 21:21 Speaker A around a gene without fully understanding why that gene exists in the first place. And that brings us back to the oldest question in this whole story, the one that was waiting quietly in that New York laboratory in 1940 and 21:33 Speaker A has never fully been answered since. Not where did Rh negative blood come from in the sense of which chromosome, which deletion, which genetic pathway. We know that part reasonably well. But where did it come from in the deeper sense, the 21:47 Speaker A human sense, which people carried it first? What world did they live in? What pressures, what landscapes, what events shaped the populations where this gene first took root and decided against considerable odds to stay? That answer lives not in a laboratory, but in the 22:04 Speaker A ground, in the bones of people who died thousands of years before anyone thought to name what ran through their veins. 22:12 Speaker A And it lives most insistently in one very specific mountain range in a culture so ancient and so isolated that studying it feels less like history and more like archaeology of the living. 22:26 Speaker A Because those people are still there, still speaking their impossible language, still carrying in the highest concentrations anywhere on Earth the blood signature that started this whole conversation. What their story reveals about the origins of Rh negative blood and about the much larger question of 22:42 Speaker A who the first Europeans actually were is something that recent ancient deoxy ribboucleic acid research has only just begun to pull into focus. And it is considerably stranger and considerably more moving than anything the theories had predicted. There is a region in 22:59 Speaker A southwestern Europe tucked between the Atlantic Ocean on one side and the spine of the Pyrenees mountains on the other where something remarkable has been quietly happening for a very long time. 23:10 Speaker A The landscape itself feels like it has been left behind by history rather than shaped by it. Green valleys folding into gray limestone ridges. Fishing villages where the same family names have appeared on the same docks for generations beyond counting. stone farm 23:27 Speaker A houses that look as though they grew out of the hillside rather than being built upon it. If you drove through this country without knowing anything about it, you might think beautiful, remote, old, and you would be right on all three 23:42 Speaker A counts. But you would not be close to understanding just how old or just how remote or what that remoteness has preserved inside the people who live there. This is the Basque country and it is by almost any scientific measure the 23:56 Speaker A strangest genetic island in the western world. I want to be careful here because strangest is a word that gets thrown around a lot when people talk about the Bas and it sometimes carries an edge of othering as if strange means lesser or 24:09 Speaker A separate in some uncomfortable way. It does not mean that here. What it means is this. The bases are in the very specific language of population genetics an outlier. a population that does not fit the patterns that explain almost 24:24 Speaker A everyone else in Europe. And that outlier status, that quiet, stubborn refusal to be absorbed into the genetic mainstream, turns out to be one of the most important clues we have about what Europe looked like before the world we 24:37 Speaker A recognize began. Start with the language because the language is where the strangeness becomes undeniable. 24:44 Speaker A Bascara as its speakers call it is what linguists classify as a language isolate. That term sounds technical, but what it means in practice is almost poetic in its loneliness. Uscara has no known relatives anywhere on Earth. Every other language spoken in Europe today 25:03 Speaker A belongs to a family Indo-Uropean, which includes everything from English and Spanish to Hindi and Russian, all tracing back to a common ancestral tongue spoken on the Eurasian step several thousand years ago. Celtic languages, romance languages, Germanic languages, Slavic languages. They're all 25:24 Speaker A cousins, separated by time and migration, but recognizably connected when you look at the deep structure of their grammar and vocabulary. Even languages that seem wildly different, like Lithuanian and Persian, share grammatical bones that linguists can identify with confidence. Usara shares 25:42 Speaker A none of those bones. Its grammar operates on principles that have no parallel in any neighboring tongue. Its vocabulary has no cognates, no words that echo back to anything spoken anywhere else. When linguists have tried to link it to other languages, including 25:58 Speaker A extinct ones like Iberian or Aquitanian from Roman era inscriptions, the connections are tentative at best and contested among specialists. The working consensus held with some frustration is that Yuscara is simply itself, a language that developed in isolation for 26:17 Speaker A so long that it became wholly structurally alien to everything around it. A relic of a linguistic world that was otherwise completely replaced. Now, here is the thing that makes this linguistically interesting fact also genetically interesting language. And genes in population history tend to 26:34 Speaker A travel together. Not always, not perfectly. But when a group of people maintains a distinct language across thousands of years, it usually means they maintained a degree of genetic separation as well, that the walls keeping the language in were also to some extent keeping outside 26:50 Speaker A genes out. And when researchers began sequencing the genomes of both ancient and modern bases in earnest over the past decade, what they found confirmed exactly that. In 2015, a team led by population geneticist Matias Yakobson at Upsala University in Sweden extracted 27:09 Speaker A and sequenced the full genomes of eight ancient skeletons recovered from a cave called Elportalon, located in the heart of Basque country in northern Spain. 27:20 Speaker A These skeletons dated to the Neolithic period somewhere between 5,000 and 3,500 years ago. The researchers then compared those ancient genomes against the genomes of modern bases, modern Europeans, ancient hunter gatherers, and ancient farming populations from across the continent. What emerged was a 27:39 Speaker A picture that surprised even the researchers who assembled it. The modern bases were more closely related to those 5,000-year-old farmers from Elportalon than to any other ancient group tested. 27:50 Speaker A And those ancient farmers in turn carried genetic signatures that set them apart from later European population specifically. They showed much lower levels of ancestry from the step migrations that transformed the rest of Europe's genetic landscape during the Bronze Age. What this means translated 28:07 Speaker A out of the technical language while the rest of Europe was being genetically remade by successive waves of migration first by Neolithic farmers from Anatolia then by Yamna pastoralists from the Pontic step. The population that would become the Basques remained 28:22 Speaker A comparatively untouched. They absorbed some of these influences as any population inevitably does. But in proportion to their neighbors, they held on to something older, something that predates the genetic revolutions that made modern Europe look the way it does. 28:37 Speaker A A follow-up study published in 2021 by researchers at Pompo Fabra University in Barcelona went even further, analyzing nearly 2,000 modern and ancient genomes from the Basque country and surrounding regions. That study found that the genetic continuity among bases has 28:55 Speaker A persisted with remarkable stability since at least the Iron Age and that the language barrier between Basque speakers and their neighbors appears to have functioned over millennia as a genuine barrier to genetic exchange as well. The researchers noted something striking. 29:11 Speaker A The bases show lower proportions of Levventine and Iranian Neolithic ancestry than virtually any other European group and higher proportions of early Anatolian farmer ancestry, suggesting that the specific mix of ancient populations that settled in the Pyreneian region very early in European 29:30 Speaker A prehistory has remained the dominant genetic signature there ever since. This is the key to understanding why the bases carry so much RH negative blood. 29:40 Speaker A It is not some exotic mutation that appeared specifically in them. It is something far more interesting. They are a window, a preserved sample of what the genetic landscape of Western Europe looked like before the great migrations of the Neolithic and Bronze Age swept 29:55 Speaker A through and diluted the older populations. The people who carried the RH negative gene in high proportions were already there in the mountain refugees of southwestern Europe long before agriculture arrived. And because the bases, for reasons of geography, cultural insularity, and perhaps sheer 30:14 Speaker A stubbornness, never fully merged with the populations that came after they held on to that ancient genetic heritage in concentrations that have since become vanishingly rare everywhere else. Does it strike you as remarkable? Just pause on this for a moment, that a mountain 30:30 Speaker A range could preserve a blood type across 10,000 years of history. that the Pyrenees, which are not even the tallest mountains in Europe, managed to do what vast distances and entire oceans could not do for other ancient populations. 30:43 Speaker A The Alps did not protect their early inhabitants from the Bronze Age migrations. The Carpathians did not. The Scandinavian ranges did not. But the western Pyrenees combined with the cultural cohesion of the people living within them created a kind of genetic 30:59 Speaker A amber, a medium in which ancient traits were suspended, preserved, carried forward into the modern world almost intact. And here is something that rarely appears in the popular discussions of Basque genetics because it complicates the tidy narrative. The bases are not simply the highest in Rh 31:17 Speaker A negative blood. They're also among European populations notable for extraordinarily high frequencies of blood type O, the universal donor type, and unusually low frequencies of blood type B. Some researchers have interpreted this combination, the elevated O, the minimal B, the high R 31:38 Speaker A negative as a coherent genetic signature of that ancient prenolithic European population. a signature that elsewhere in Europe has been diluted and overwritten by thousands of years of mixing, but which survives in the Basque country in something closer to its original form. 31:55 Speaker A There is also a social dimension to the Basque story that tends to be overlooked historically, and this is documented as far back as medieval Basque legal codes. 32:05 Speaker A Basque society operated under inheritance laws that gave women significantly more property rights and household authority than was typical elsewhere in Europe at the time. 32:15 Speaker A Daughters could inherit equally with sons. Widows controlled family property. The household or exuscara was the fundamental unit of Basque social organization and it descended through the family line regardless of gender. 32:30 Speaker A Some historians have pointed to this as evidence of a pre-Indo-European social structure, a cultural layer as ancient as the language itself preserving customs from a time before the patriarchal norms brought by the step migrations reshaped European society. It 32:48 Speaker A is a fascinating possibility and it is difficult to prove but it fits. It fits the broader picture of a people who were not simply geographically isolated, but culturally insulated in a way that went deeper than geography alone. The 33:03 Speaker A question of where the Basque's ancestors actually came from, and with them, the gene that makes their blood behave the way it does is one that modern genomics has been chipping away at steadily. 33:14 Speaker A The answer, as of the most recent research, points not to some mysterious external origin, but to something more grounded and in many ways more astonishing. They descend in significant part from the people who were already in Europe when the last great ice age 33:29 Speaker A ended. The original inhabitants, the ones who painted the animals on the cave walls, the ones who survived the glacial maximum by retreating into the refuges of southwestern Europe, the Iberian Peninsula, the Pyrenees, the Francoantabrian coastal strip, and who 33:46 Speaker A emerged when the ice receded to find themselves among the oldest continuous occupants of the continent. Scholars still debate the exact proportions and pathways of this ancestry. The picture is not yet complete and it may never be fully resolved given the fragmentaryary 34:02 Speaker A nature of the ancient deoxyriboucleic acid record. But what the evidence strongly suggests is that the people who became the bases are in a very real sense the closest living genetic link to the ice age Europeans to the people who 34:15 Speaker A were here first. And those ice age Europeans, those original inhabitants of the continent, the ones who retreated into the mountain refugees while glacias covered the north, are exactly where the trail of Rh negative blood leads next. 34:30 Speaker A Because to understand how this gene could have survived 35,000 years, carried across the upheavalss of the Neolithic, the Bronze Age, the Iron Age, and into the modern world, we have to go back to the time before any of that. We 34:43 Speaker A have to go back to the ice age itself. To the caves, to the artists, to the people who held torches in darkness and painted creatures on stone walls that we are still standing in front of, still trying to understand 20,000 years later. 34:57 Speaker A The year is 1994, December. the Adesh region of southern France where limestone cliffs drop steeply into a river gorge and the hillsides are riddled with the kind of small half-hidden cave entrances that locals have been walking past for generations 35:14 Speaker A without thinking much about them. Three cavers, Jean Marie Chaveet, Elliot Brunell, and Christian Elair, are following a draft of cold air through a narrow passage when the ground drops away beneath them, and they find themselves standing at the edge of an 35:28 Speaker A underground chamber so large their flashlight beams cannot reach the far wall. They move deeper and then they stop. The walls are covered. Horses in mid gallop, their legs blurred with a technique so sophisticated it looks almost like motion blur in a photograph. 35:45 Speaker A A pride of lions hunting their bodies low and tense, rendered with a naturalism that would not look out of place in a modern wildlife documentary. 35:55 Speaker A Woolly rhinoceroses facing each other, their horns lowered their posture unmistakably aggressive. Mammoth's cave bears a panther. Panel after panel after panel wrapping around the curved stone walls of a chamber that has been sealed from the outside world for somewhere 36:10 Speaker A around 25,000 years. Jean Marie Chauve would later write that his first instinct standing in that darkness with a headlamp trembling in his hand was that he was dreaming. His second instinct was that he was an intruder, that this place belonged to someone 36:26 Speaker A else, had always belonged to someone else, and that he was only now receiving permission to enter. The Chauveet cave, as it became known, is dated to approximately 32,000 years ago. That makes it roughly twice as old as the 36:39 Speaker A Lasco cave paintings in the Dordona, which were discovered in 1940 and had long been considered the pinnacle of ice age art. What Chauave revealed was that human beings were making art of extraordinary technical complexity, using perspective, using shading, using 36:56 Speaker A the natural contours of the cave wall to give their subjects three-dimensional form at a time when the most recent scientific consensus had assumed our ancestors were still in the relatively early stages of developing symbolic thought. The discovery did not just add 37:12 Speaker A years to the record. It forced a rethinking of what kind of people these were. Who were they exactly? We call them anatomically modern humans, which is accurate but not very illuminating. 37:24 Speaker A We sometimes call them crowagnon, which was a name attached to the first such skeleton found in France in 1868 in a rock shelter near the village of Less Aes. They looked like us. Their brains were the same size as ours, possibly 37:39 Speaker A slightly larger. They used tools, wore jewelry made from shells and pierced animal teeth, buried their dead with grave goods. In some places, they traded raw materials across distances of several hundred km. They were not primitive in any meaningful sense of 37:55 Speaker A that word. They were us at an earlier address. In the language of modern genetics, these people are classified as western hunter gatherers, a population grouping that researchers used to describe the ancient foraging communities who inhabited Europe before the arrival of Neolithic farmers from 38:11 Speaker A southwestern Asia. And this is where the story of ice and art and ancient humanity intersects for the first time with the specific question of blood. 38:20 Speaker A Ancient deoxyriboubonucleic acid analysis of western hunter gatherer remains work pioneered at Harvard by geneticist David Reich and his collaborators building on earlier foundational studies by teams at the Max Plank Institute for evolutionary anthropology in Leipig has begun to 38:38 Speaker A reveal the genetic makeup of these ice age Europeans in remarkable detail. Among the traits that appear consistently in western huntergatherer genomes, a high prevalence of the genetic variant associated with Rh negative blood. Estimates from multiple studies place the frequency somewhere in 38:57 Speaker A the range of 20 to 25% among these ancient populations substantially higher than what is found today in most European populations outside the Basque country and dramatically higher than the frequencies seen in the Neolithic farmer genomes that began arriving from the east 39:15 Speaker A several thousand years later. Those farming populations from southwestern Asia, the analyses consistently show, carried the Rh negative variant at much lower rates somewhere between 3 and 6%. 39:28 Speaker A Let that sink in for a moment. The people painting lions and rhinoceroses on cave walls by torch light 30,000 years ago were carrying the same blood signature at high frequencies as the bases carry today. The genetic thread that the Basques have preserved, the one 39:44 Speaker A that makes them a window into prenolithic Europe, does not start in the Neolithic. It runs deeper. It runs all the way back to the artists. Now, I want to be transparent about something here because I think intellectual honesty matters more than a clean 39:58 Speaker A narrative. We cannot yet point to a specific ice age skeleton and say this individual was definitively RH negative. 40:06 Speaker A And here is the confirmed sequence to prove it. The ancient deoxy ribboucleic acid record for this period is fragmentary. And the older the specimen, the harder it is to extract usable genetic material from bone. What researchers can do is work with 40:23 Speaker A population level statistics, look at the frequencies of the relevant genetic variants across multiple ancient genomes from the same time period and region, and make probabilistic inferences. Those inferences across multiple independent research groups and multiple data sets point consistently in the same 40:41 Speaker A direction. High RH negative frequency in western hunter gatherer populations. Low RH negative frequency in the Anatolian Levventine farming populations that followed. The math in broadstrokes holds. But let's step back from the genetics for a moment and just sit with 40:58 Speaker A these people as human beings. Because I think the clinical language of population genetics can sometimes rob us of something important. The simple fact that these were people, real people with families and fears and inside jokes we will never know. People who had 41:13 Speaker A favorites among the animals they painted. people who noticed that certain cave walls resonated like drums when you struck them, and who painted their most elaborate scenes precisely there in the acoustic sweet spots, as if they understood that the image and the sound 41:28 Speaker A together created something neither could accomplish alone. Researchers studying the acoustic properties of decorated caves in France and Spain have noted this pattern, the correlation between heavy decoration and acoustic resonance. And while the interpretation remains debated, it suggests a relationship between these 41:47 Speaker A artists and their chosen spaces that goes well beyond simple recordkeeping. Here is a detail that I have thought about many times and cannot quite let go of at both Chauveet and at the much older cave site of Garas in the French 41:59 Speaker A Pyrenees dated to roughly 25,000 years ago. There are stencled handprints, dozens of them, made by pressing a hand flat against the rock and blowing pigment around it, leaving a negative image of the hand in ochre or charcoal or manganese dioxide. These handprints 42:17 Speaker A are one of the most recognizable images from Ice Age art. You have probably seen photographs of them. What the photographs rarely convey is something that is immediately visible when you look at the highresolution documentation of the Garas hands. In particular, a 42:33 Speaker A significant proportion of them appear to show missing fingers, shortened digits, hands that not quite complete. The debate about what this means has run for decades. 42:44 Speaker A Some researchers argue the fingers were folded down deliberately as a kind of hand signal language. Others suggest the hands belong to people who had suffered frostbite during the brutal cold of the last glacial maximum, a period when temperatures in southern France were 10 42:59 Speaker A to 15° centigrade colder than today, and the landscape looked more like modern Siberia than the green countryside it is now. A smaller number of researchers have proposed that the shortened digits indicate a hereditary condition that ran in certain lineages. Nobody knows. And 43:16 Speaker A that uncertainty is itself a kind of portrait, a reminder that these people were complex enough to leave us questions we still cannot answer. What we do know is this. The climate they were living through was by any measure 43:27 Speaker A extreme. The last glacial maximum, which peaked roughly 22,000 years ago and began retreating around 18,000 years ago, pushed the great ice sheets as far south as what is now northern Germany and the British Isles. The northern twothirds of Europe was either under ice 43:44 Speaker A or a frozen treeless tundra where almost nothing could survive. The populations of modern humans who had been moving into Europe were compressed southward into the refugeia the ice-free pockets along the Atlantic coast in Iberia in the Francoantabrian region in parts of 44:02 Speaker A Italy and the Balkans. They did not simply move there and wait. They lived for thousands of years during one of the harshest extended climatic episodes in human prehistory. They maintained communities, raised children, created art, developed traditions that their 44:18 Speaker A descendants would carry forward even when the world outside the caves finally thored. Geneticists now refer to these southern refugeia as the source populations for the postglacial recolonization of Europe. When the ice retreated roughly 15,000 years ago, the descendants of these ice age survivors 44:37 Speaker A moved northward and eastward, reoccupying the continent. They carried their languages. They carried their tools. They carried their genes. And among those genes at frequencies substantially higher than would be found in the populations arriving later from the south and east was the RH negative 44:56 Speaker A variant, the variant that makes certain blood incompatible with everything around it. The variant that Lan Steiner and Viner found in a New York laboratory 80 years ago, still quietly persisting in the blood of people who had no idea they 45:10 Speaker A were carrying something so ancient. There is something that strikes me as almost unbearably poetic about this. If you will permit me, a moment of pure sentiment, the same gene that helped define the people who made the oldest art in the world is still being found 45:25 Speaker A today in the descendants of the people who stayed closest to where those artists once lived. The basks, those genetic time capsules tucked into their mountain valleys, are carrying in a very literal molecular sense the inheritance of the cave painters. Not as myth, not 45:41 Speaker A as metaphor, as biology, as of course the story did not end when the ice age did. That would have been too simple, and history is never simple. The world that the ice age survivors inherited, the warming, greening, slowly 45:56 Speaker A repopulating Europe of 12 to 8,000 years ago, was about to be disrupted again. Not by glaciers this time, but by something in many ways more transformative people. New people arriving from the east carrying not just different genes, but an entirely 46:11 Speaker A different relationship to the land. People who did not follow herds across open tundra, who did not read animal behavior in the mud beside a watering hole, who did not spend their winters painting by firelight in the dark, people who had learned to make the land 46:26 Speaker A feed them. The arrival of farming in Europe and what it did to the populations who were already there, and specifically to the gene that had been running quietly through their blood for 30,000 years, is one of the most 46:38 Speaker A consequential stories in human prehistory. And it is exactly what we need to look at next. Roughly 9,000 years before the present, on a low hill in what is now southeastern Turkey, a group of people began doing something that would eventually change everything 46:54 Speaker A about how human beings live. They were not the first people to notice that certain grasses, if tended carefully, produced more seed than others. They were not the first to observe that wild animals kept close, became less wild over generations. But in this particular 47:10 Speaker A region, the upper stretches of the Tigress and Euphrates River system in the ark of land that archaeologists have long called the fertile cresant, the practice crystallized into something systematic intentional transmissible a technology not of stone or bone, but 47:26 Speaker A of relationship, a new kind of contract between human beings and the living world around them. We call it agriculture. and the ripple effects of its invention are still washing through us through our cities, our diseases, our social hierarchies, our bodies, and yes, 47:41 Speaker A our blood. The site that perhaps best captures the strange moment just before the agricultural revolution fully arrived, is one that was not excavated until 1994, the same year, coincidentally, that Jean Marie Chau and his companions were crawling through a 47:58 Speaker A different darkness on the other side of the Mediterranean. The site is called Gobecepe located on a limestone ridge in southern Turkey. And what the German archaeologist Klaus Schmidt found there when he began systematic excavation upended nearly everything scholars 48:15 Speaker A thought they understood about the sequence of events that produced civilization. Gobec is a complex of massive carved stone pillars. Some standing nearly 6 m tall, weighing up to 20 tons, arranged in circular enclosures and covered with intricate relief carvings of animals, 48:34 Speaker A foxes snakes vultures scorpions wild bo. The carvings are accomplished, the construction monumental. The planning clearly the product of organized communal effort on a significant scale. 48:48 Speaker A And here is the thing Gobeclete predates agriculture. The site was built by hunter gatherers, people who, as far as the evidence shows, had not yet settled into permanent farming communities, had not yet domesticated the crops that would define the Neolithic world. They 49:04 Speaker A were building temples or something like temples before they were building granaries which suggests in a way that archaeologists are still grappling with that the religious impulse and the social impulse toward permanent settlement may have come first and that 49:18 Speaker A agriculture followed as a consequence of people needing to feed the groups that gathered at sites like this one rather than the other way around as the traditional story had it. Klaus Schmidt himself who excavated Gobeclete until his death in 2014 was fond of saying 49:33 Speaker A that the site had turned the standard narrative on its head. First came the temple, he wrote, then the city. What Gobecley helps us see is that the transition from hunting and gathering to farming was not a sudden switch. It was 49:48 Speaker A a long, complicated, region-specific negotiation between human communities and their landscapes playing out across centuries and millennia in ways that varied enormously from place to place. 50:00 Speaker A But the endpoint, the fully committed agricultural community dependent on domesticated grains and herded animals, organized around permanent settlement, that endpoint was in genetic terms carried by a specific population. And when that population began moving westward into Europe, beginning roughly 50:16 Speaker A 8,000 to 9,000 years ago, they carried it with them into a world that already had people in it. The question of what actually happened when farmers met hunters in Neolithic Europe is one that ancient deoxxyribboucleic acid research has transformed in the 50:32 Speaker A past decade. And the picture that has emerged is considerably more complicated and considerably more sobering than the sanitized version that used to appear in textbooks. 50:43 Speaker A For a long time, the dominant assumption among archaeologists was that the spread of farming across Europe was primarily a spread of ideas that local hunter gatherer populations learned agricultural techniques from their neighbors and gradually adopted them so that the genetic composition of Europe's 50:59 Speaker A population changed relatively little while the culture changed dramatically. This model was called the cultural diffusion hypothesis and it was popular partly because it was tidy and partly because it avoided uncomfortable implications. Ancient deoxyribboucleic acid dismantled it almost completely. 51:19 Speaker A Studies published between 2015 and 2019 drawing on hundreds of ancient genomes from Neolithic and Bronze Age sites across Europe showed that the spread of farming into Europe was not primarily a spread of ideas. It was a spread of 51:34 Speaker A people. The genetic signature of Anatolian Neolithic farmers, a distinctive profile that differs markedly from that of the western hunter gatherers who preceded them, appears suddenly and in high proportions across central and northern Europe in the archaeological record beginning around 51:51 Speaker A 7,500 years ago. In sight after sight, the pattern is the same hunter gatherer ancestry drops sharply. Anatolian farmer ancestry rises to dominance and the transition happens within what is in geological terms a very short window. 52:07 Speaker A Johannes Krower, director of the department of archoggenetics at the Max Plank Institute for Evolutionary Anthropology, led several of the most significant studies in this area. His team's findings along with parallel work by David Reich's group at Harvard and 52:22 Speaker A Wolf Gang Hark's international collaborations painted a consistent picture. The Anatolian farmers did not simply teach the existing Europeans how to farm. They replaced them not completely, not everywhere, not without mixture, but substantially and measurably. 52:40 Speaker A In some regions of central Europe, huntergatherer ancestry in the post- Neolithic population drops to levels below 10%. 52:49 Speaker A The people who had lived there for tens of thousands of years, the descendants of the ice age artists, the carriers of the ancient blood were marginalized, absorbed or simply gone from the genetic record in the span of a few centuries. 53:02 Speaker A Now, before anyone gets the wrong impression here, and I want to be careful because this is territory where popular narratives can easily slide into something misleading. 53:12 Speaker A What the genetic shows is population replacement in a demographic sense. It does not tell us specifically how that replacement happened and the archaeological evidence for this period suggests a range of possibilities. 53:26 Speaker A In some areas, there is evidence of violent conflict. The site of Talheim in southwestern Germany dated to approximately 7100 years ago contains the remains of 34 individuals, men, women, and children who had been struck down with farming tools and stone axes 53:43 Speaker A and deposited in a mass grave. The skeletal analysis indicates that most of the victims were from a local huntergatherer community. A similar site at Aspan Schllets in Austria contains the remains of at least 67 individuals, again showing evidence of coordinated 54:01 Speaker A large-scale violence and again dated to the early Neolithic, the period of maximum contact and competition between incoming farmers and resident hunters. 54:11 Speaker A These sites do not define the whole story. There was also coexistence intermarriage and gradual absorption in many regions. But the genetics makes clear that in aggregate the outcome was not a gentle blending. It was a demographic transformation on a 54:26 Speaker A continental scale. What tends to get lost in these discussions and what I find particularly interesting from the perspective of human health rather than just human history is the fact that the farmers who displaced the hunters were not in any simple biological sense 54:42 Speaker A thriving. This is perhaps the most counterintuitive finding in the entire archaeology of the Neolithic transition, and it deserves more attention than it typically receives. 54:53 Speaker A When physical anthropologists examine the skeletal remains of early Neolithic farming communities and compare them to the hunter gatherer populations that preceded them, in the same regions, the farmers consistently show worse indicators of health. Their teeth are more heavily worn and morearious dental 55:11 Speaker A cavities essentially unheard of among hunter gatherers whose diet was varied and low in fermentable carbohydrates became common with the adoption of grain-based diets. Their bones show more evidence of nutritional stress, particularly deficiencies of iron and vitamin D. Their average height dropped. 55:30 Speaker A In many cases, their lifespans appear to have been shorter. So why did farming win? Not because it made individuals healthier, but because it made groups more numerous. A farming community, even one subsisting on a nutritionally inferior diet, can support dramatically 55:46 Speaker A higher population densities than a huntergatherer community ranging over the same territory. More children could be fed, even if each child was somewhat less wellnourished than its huntergatherer equivalent. More adults could be sustained in a given area. And in the long mathematics of demographic 56:04 Speaker A competition, numbers tend to determine outcomes regardless of who is individually stronger or healthier. The gene that have been running through huntergatherer blood for 30,000 years present at 20 to 25% in western huntergatherer populations, as the ancient genomic studies suggest, was now 56:23 Speaker A being diluted. With each generation of intermarriage between the resident huntergatherer communities and the incoming farmers, the proportion of the older ancestry decreased. In most of Europe, within perhaps 2,000 years of the initial arrival of Neolithic farmers, the western hunter gatherer 56:41 Speaker A contribution to the local gene pool had been reduced to a fraction of what it had been. And with it, the frequency of RH negative blood dropped substantially persistently across nearly the entire continent. Nearly, not quite. Because not all landscapes are equally 56:57 Speaker A penetrable. Not all communities are equally accessible to newcomers. In the places where geography or culture or both acting together provided a barrier to the demographic tide, something older survived. The coastal fringe of Western Ireland, where the Atlantic itself 57:13 Speaker A formed a boundary on one side, and the terrain was rugged enough to discourage easy settlement. The western highlands of Scotland, where the land is thin and the weather is legendary in its unpleasantness. The Atlantic coast of Norway, where fishing communities 57:28 Speaker A maintained a way of life distinct enough from inland agricultural patterns to preserve a degree of genetic separation. 57:37 Speaker A And most persistently and most completely of all the Western Pyrenees were a mountain barrier and an impenetrable language combined to create the most durable genetic refuge on the continent. These pockets were not static. People moved in and out, traded, 57:51 Speaker A intermarried across their edges. The isolation was never absolute, but it was enough. Enough to keep the older ancestry alive at higher proportions than anywhere else in the farming world. 58:03 Speaker A Enough to preserve in measurable concentrations the blood variant that the cave painters had carried. There is a common misconception worth addressing directly because it circulates widely and confidently in popular discussions of this topic. the idea that Rh negative 58:19 Speaker A blood appeared in Europe as a result of the Neolithic transition that it is in some sense a gift of the farming populations. The genetic evidence says the opposite. The farming populations from Anatolia carried Rh negative at low frequencies around 3 to 6% by most 58:38 Speaker A estimates. The hunter gatherers they encountered and largely replaced carried it at four to five times that rate. The arrival of farming in Europe did not introduce or amplify Rh negative blood. 58:50 Speaker A It diluted it. The blood is older than the farmers, older than agriculture, older than any social structure we would recognize as civilization. That distinction matters not just as a historical footnote, but as a key to understanding what we are actually 59:06 Speaker A looking at when we track Rh negative blood across time and populations. We are not looking at a new development. We are looking at a remnant, a signal from a world that was largely overwritten, preserved in the places where the 59:19 Speaker A overwriting was incomplete. And some of those places, it turns out, were not remote mountain valleys or foggy Atlantic islands. Some of them were palaces. Some of them were thrones because the gene that retreated into the refugee of the Atlantic fringe did not 59:34 Speaker A stay hidden in anonymity forever. Over the centuries that followed, through patterns of marriage and alliance and dynastic calculation that nobody at the time understood in biological terms, it found its way into some of the most powerful bloodlines in European history 59:50 Speaker A with consequences that were depending on how you look at them either tragic or worldshaping and in some cases both at once. Meniest Madrid, the year 1700. In the Royal Alcaza, behind doors that opened only for the most trusted members of the 60:08 Speaker A court, a man lay dying who had arguably never truly lived. He was 38 years old, though by most accounts he looked considerably older. His body so compromised by a lifetime of illness that contemporaries struggled to find the words to describe what they saw 60:24 Speaker A without seeming to be unkind. He could barely chew his own food. He had suffered seizures throughout his childhood. He walked with difficulty, spoke with difficulty, and had never in 35 years of marriage across two different wives managed to produce a 60:39 Speaker A child who survived. His name was Charles II of Spain. He was the last of the Spanish Habsburgs and his death without an heir would ignite the war of the Spanish succession, a conflict that reshaped the political map of Europe and 60:54 Speaker A left somewhere between 400,000 and a million people dead. His autopsy conducted the following morning was described by the physicians who performed it in terms that shocked even them. The report preserved in Spanish court archives noted that his heart was 61:09 Speaker A the size of a peppercorn. His lungs were corroded, his intestines were gangrous, his single testicle was black as coal, his skull contained no blood at all. 61:21 Speaker A Whether these descriptions were entirely accurate or partially exaggerated by men trained more in classical medicine than modern anatomy is difficult to say, but they were consistent with something that modern scientists working 300 years later with genealogical records and 61:37 Speaker A genetic modeling software would eventually be able to calculate with uncomfortable precision. Charles II of Spain had an inbreeding coefficient of approximately 0.254. 61:49 Speaker A To put that number in context, a child born to siblings who share both parents has an inbreeding coefficient of approximately 0.25. 61:58 Speaker A Charles, the product of generations of carefully arranged dynastic marriages within and between branches of the same family, was roughly as genetically compromised as if his parents had been brother and sister. But his parents were not brother and sister. They were uncle 62:15 Speaker A and niece. And before them, the compression had been building for generations the deliberate systematic dynasty preserving practice of keeping the Habsburg bloodline within the Habsburg bloodline across six generations and well over a century of marital calculation. The study that 62:33 Speaker A produced that figure was published in 2009 by geneticist Gonzalo Alvarez and his colleagues at the University of Santiago de Compostella. 62:42 Speaker A They reconstructed the pedigrees of more than 3,000 individuals across 16 generations of Habsburg genealogy, tracing the accumulation of shared ancestry through the marriage records that Spanish and Austrian royal courts had kept with meticulous care. What they found was that the inbreeding 63:00 Speaker A coefficient of the Spanish Habsburg line increased steadily from the late 15th century onward from manageable levels in the reign of Ferdinand and Isabella to the catastrophic levels represented by Charles. 63:13 Speaker A Infant mortality within the dynasty the study noted ran at roughly 30% against a background rate of about 20% for the general Spanish population of the same period. 10 percentage points of extra death explained not by divine punishment or bad luck, but by the compounding 63:30 Speaker A mathematics of shared ancestry. Now, here is where I want to introduce something that most histories of the Habsburgs do not discuss. Not because it has been hidden, but because the tools to think about it clearly were not available until relatively recently. The 63:45 Speaker A Habsburg story is almost always told as a story about inbreeding. In the conventional genetic sense, the accumulation of harmful recessive mutations expressed when two copies of the same defective gene are inherited from closely related parents. And that explanation is real and well documented. 64:06 Speaker A But there is a second layer to the Habsburg tragedy that the conventional inbreeding narrative does not fully account for. And that layer involves blood. Specifically, it involves the possibility that within this extraordinarily tight marriage network, the biological incompatibility between 64:23 Speaker A Rh negative mothers and Rh positive fetuses may have been operating silently alongside the better understood effects of genetic compression. 64:34 Speaker A No historian can confirm the blood types of the Habsburg monarchs. That information was not recorded and no biological sample suitable for that kind of analysis have been confirmed as authentic from this period. Let me be clear about that. What follows is not 64:50 Speaker A established fact. It is a line of reasoning, a hypothesis that some researchers in reproductive medicine and historical demography have found worth considering. And I think it is worth laying out carefully and letting you assess it for yourself. The Spanish 65:05 Speaker A Habsburg dynasty drew its founding blood from several distinct lineages. The Castellian, the Araggones, the Beondian, and the Portuguese. Among the populations of the Iberian Peninsula and the Atlantic fringe of Europe during this period, our H negative blood frequencies were among the highest in 65:23 Speaker A the world, consistent with the deep western huntergatherer ancestry that we have already traced in these populations. In a dynasty that married almost exclusively within itself and within a geographically limited aristocratic pool, the probability that both RH negative carriers and the cross 65:42 Speaker A RH pairings that create immunological risk would have been present is statistically not trivial. The pattern of infant loss within the Habsburg line has some features that align uncomfortably well with what we know about hemolytic disease of the newborn. 65:57 Speaker A specifically first children tending to survive subsequent children dying at higher rates. Anna of Austria, daughter of Philip III of Spain and Margaret of Austria and later Queen of France as wife of Louis I 13th experienced five pregnancies between 1619 and 1632. 66:18 Speaker A The first child a boy was still born. The second, third, and fourth pregnancies also ended in infant deaths. 66:26 Speaker A Only the fifth, the future Louis the 14th of France survived. Louisie was born in 1638 after 23 years of marriage so late that his birth was widely considered a miracle, prompting the nickname Louie Judon, meaning Louis the God-given. The pattern is striking. 66:43 Speaker A It does not prove an RH incompatibility. There are other explanations, infection, other genetic factors, the generally poor standards of obstetric care available even to queens. But the sequence repeated losses with the survivor arriving late in the series is 66:59 Speaker A the kind of pattern that physicians who specialize in maternal fetal medicine recognize. It appears in the histories of several other Habsburg connected women. The evidence is suggestive without being conclusive, which is exactly the kind of evidence that history tends to deal in. What is not in 67:16 Speaker A question is the practical outcome. The Spanish Habsburg line ended with Charles II because there was no child to follow him. The Austrian line continued longer but experienced its own sustained pattern of infant mortality and reproductive difficulty that historians 67:32 Speaker A have generally attributed to inbreeding and that may in some cases have had an additional biological dimension that contemporaries could not identify. 67:43 Speaker A The court physicians of the 17th century were not equipped to distinguish between a miscarriage caused by chromosomeal abnormality, one caused by infection, and one caused by maternal antibodies attacking fetal blood. They saw the outcomes. They recorded them faithfully. 68:00 Speaker A They explained them in the language available to them, Providence Constitution, the weakness of the royal body, and moved on. There is something I find deeply moving about this in a quiet and melancholy way. 68:12 Speaker A The women at the center of these tragedies, Anna of Austria, Margaret of Austria before her, Maria Anna of Spain, and her predecessors were not passive figures. They were politically active, intellectually engaged in many cases, deeply pious and stoic in the face of 68:29 Speaker A losses that would have broken most people. Anna of Austria managed the French Regency for her son after Louis the 13th's death. She was by the accounts of people who knew her formidable. And she spent two decades losing children without ever 68:44 Speaker A understanding why in a world that offered her theology and bloodletting and prayer as its best available medicine. That gap between the biological reality and the explanatory frameworks available to people living through it is one of the recurring themes of this entire story. 69:01 Speaker A The same gap appears in the medieval households where Rh negative women lost pregnancy after pregnancy. It appears in the royal courts where physicians noted patterns they could not explain. It appears every time a biological fact goes unnamed for centuries while the 69:18 Speaker A human consequences of it accumulate in the historical record waiting for someone with different tools to read them backward and finally understand what was happening. A separate and rather more dramatic illustration of how bloodrelated royal tragedy was interpreted before modern medicine 69:33 Speaker A understood it comes not from Spain but from England specifically from the figure that history knows as Bloody Mary. 69:43 Speaker A Mary I of England, daughter of Henry VIII and Catherine of Araggon experienced two phantom pregnancies during her reign episodes in which her abdomen swelled. Her period ceased. She experienced symptoms consistent with pregnancy and then months later nothing was born. These episodes remain 70:03 Speaker A medically puzzling even today. Some historians attribute them to uterine fibroids or cancer which ultimately killed her at 42. Others have speculated about psychological components. What is clear is that her desperate hope for an heir, an heir who would secure the 70:20 Speaker A Catholic succession she had spent her reign fighting to restore was never realized. And that the failure of her body to produce one was interpreted by her Protestant enemies as divine judgment and by her Catholic supporters as a cross sent by God to test her 70:36 Speaker A faith. Nobody at the time had a framework that included blood type as a variable. the Habsburg's Mary Tuda, the pattern of royal reproductive failure across early modern Europe. These are not, I want to be careful to say, all 70:49 Speaker A explicable by RH incompatibility. Most of them are not even clearly connected to it. The conventional genetic and medical explanations for royal dynasties of this period account for a great deal. But the possibility that one additional biological factor, invisible, unnamed, operating silently 71:08 Speaker A in the background of dynastic marriages, may have contributed to some of these patterns, is one that modern reproductive medicine has given us the tools to consider for the first time. 71:19 Speaker A The consideration is not certainty, but it is worth sitting with because here is what strikes me as the larger point beneath all the genealogy and the court archives and the genetic coefficients. 71:31 Speaker A These were human tragedies. Rooms full of grief that the people inside them could not explain. Children who arrived in the world already failing in chambers, hung with silk, and attended by the best physicians of their age, who stood there holding their instruments 71:46 Speaker A and their theories and their helplessness, unable to offer anything that would change the outcome. The mystery that shaped dynasties was not a curse. It was not punishment. It was biology specific traceable knowable hiding in plain sight inside the blood 72:02 Speaker A of people who had no idea what was in it. Understanding it does not undo the grief, but it changes the story. It makes it human in a different way. Not the story of families punished for their ambition, but the story of people caught 72:16 Speaker A in a biological truth that nobody yet had the language to speak. Which brings us to something that has always interested me about this whole question. 72:24 Speaker A Not just where Rh negative blood has been, but where it is now, how it is distributed across the world today. What the modern map of Rh negative blood actually looks like when you lay it out carefully. And what that map read 72:38 Speaker A closely continues to reveal about the deep history we have been tracing through these pages of time. Because the pattern is not random. It has a shape. 72:47 Speaker A And that shape, once you see it, tells a story all by itself. Imagine you're standing in front of a very large map of the world. Not a political map with its tidy borders and color-coded nations, but a different kind of map 73:04 Speaker A entirely, one that shows only a single variable rendered in gradients of light and shadow. The variable is frequency. 73:12 Speaker A How often in any given population does the gene for Rh negative blood appear? Where it is common, the map glows bright. where it is rare or absent, the map goes dark, and what you see when you step back far enough to take in the 73:26 Speaker A whole picture at once, is not what most people expect. It is not a smooth gradient. It is not a neat continental pattern. It is something more irregular, more interesting, and more historically legible than that. There are bright clusters in specific scattered places, 73:44 Speaker A long corridors of moderate light running along certain coastlines, and vast stretches of near darkness covering enormous swavthes of the globe, East Asia, subsahara and Africa, the Pacific, the indigenous Americas, where the gene barely registers at all. 74:01 Speaker A The map looks less like a weather pattern and more like a fossil record, like something ancient and specific preserved in the places where it was sheltered and erased in the places where it was not. I have spent considerable 74:15 Speaker A time thinking about what this map actually tells us beyond the headline numbers that tend to get repeated in popular articles on the subject. The Basque country at 35% Ireland and Scotland in the mid20s. Northwestern Europe generally elevated. Yes, all of 74:31 Speaker A that is real. And we have already explored why. But there are other points on this map less well-known and in some ways more revealing that deserve careful attention. Because taken together, they form a pattern that points towards something larger than any single 74:46 Speaker A population story. begin if you will in a place that surprises most people when it comes up in this context. The Atlas Mountains of Morocco, specifically the Berbers speaking communities of the Riff and Middle Atlas regions. Communities whose cultural distinctiveness and 75:02 Speaker A geographic isolation have drawn the attention of anthropologists for well over a century, but whose blood type distributions have received considerably less popular attention than they merit. 75:14 Speaker A Studies of Moroccan Berber populations, particularly those carried out in the latter decades of the 20th century and refined in more recent genomic work, have documented RH negative frequencies in certain Atlas Mountain communities running between 26 and 29% figures that 75:32 Speaker A place them alongside the bases at the very upper end of the global distribution. Among the general Moroccan population, by contrast, the rate is considerably lower, closer to 9 or 10%. The Atlas communities are in this one specific genetic marker dramatically different 75:50 Speaker A from the broader North African average. Why would a group of Berber highlanders in the mountains of Morocco carry Rh negative blood at rates comparable to the bases of the Pyrenees? The answer, as far as population genetics can reconstruct it, has to do with ancient 76:06 Speaker A migration patterns across the straight of Gibraltar, which it is easy to forget is only about 14 km wide at its narrowest point. For much of human prehistory, the narrow water crossing between the Iberian Peninsula and North Africa was not the barrier it might 76:22 Speaker A appear on a modern map. Ancient populations moved across it in both directions, carrying genes, languages, and technologies in ways that left traces in the genomes of both sides. The Berber populations of the Mcgreb, particularly those in the most isolated 76:37 Speaker A Highland communities, appear to carry a genetic signature that includes components traceable to populations that once spanned both sides of that crossing populations who were in the western Mediterranean world of the Mesolithic and early Neolithic among the primary carriers of the Rh negative variant. The 76:57 Speaker A Berber case is significant for another reason as well. that directly challenges the assumption and this is an assumption that circulates widely and confidently that aract negative blood is essentially a European trait. It is not. It is a trait associated with specific ancient 77:14 Speaker A population lineages that at various points in prehistory happened to be concentrated in the regions we now call Europe and the North African Atlantic fringe. The modern distribution reflects not the origin of the gene, but the subsequent history of which populations 77:30 Speaker A expanded, which contracted and which was sheltered from the demographic tides that swept through both continents in the millennia that followed. Speaking of which, let me take you briefly to the Canary Islands, roughly 100 km off the northwestern coast of Africa, because 77:46 Speaker A the story of the island's original inhabitants is one of the most underappreciated tragedies in the history of European expansion. and it has a specific relevance to this conversation that I do not think has received enough attention. The indigenous people of the Canary Islands 78:02 Speaker A known as the Guanchi were encountered by European explorers beginning in the 14th century. They were by all accounts a remarkable people, physically large, technologically sophisticated within their island context, possessed of a complex social structure and a language, or rather a family of languages that 78:21 Speaker A appears to have been related to the Berber languages of North Africa. By the late 15th century, the Spanish conquest of the islands was essentially complete, and the Guanche as a distinct population had been largely destroyed through a combination of warfare, 78:37 Speaker A enslavement, and the introduced diseases that killed indigenous peoples across the world with terrible efficiency wherever Europeans arrived. What survived in the mixed ancestry population of the modern Canary Islands were genetic traces. And those traces analyzed in studies of Canarian 78:54 Speaker A population genetics over the past two decades show something consistent with the broader pattern elevated frequencies of markers associated with the ancient Atlantic fringe populations, including in some analyses frequencies of Rh negative blood that exceed what you would expect from the European component 79:14 Speaker A of Canarian ancestry alone. The Guanche themselves, by the genetic reconstruction that is possible from their surviving descendants, appear to have carried the ancient North African and Atlantic lineage signature in concentrations that place them closer to the Berber communities of the Moroccan 79:31 Speaker A highlands than to the subsaharan African populations to their south. A people who no longer exist as a distinct culture, but whose blood in diluted and distributed form continues to carry its ancient signature in the modern population of those seven islands. There 79:49 Speaker A is one more geographic anomaly worth considering before we pull back to the larger picture. And it is one that stopped researchers cold when the data first emerged clearly enough to analyze. 80:01 Speaker A Certain communities in the Horn of Africa and the Ethiopian highlands, specifically among groups like the Amhara and the Tyigrinia of Northern Ethiopia and Eratria, show Rh negative frequencies that are substantially elevated compared to subsaharan African populations, generally where rates below 80:18 Speaker A 1% are the norm. Among these specific Ethiopian highland communities, rates in the range of 3 to 5% have been documented, which may sound low in absolute terms, but represents a dramatic outlier against the near zero background of the surrounding region. 80:36 Speaker A The explanation most consistent with the genomic evidence involves the complex ancient population history of the Horn of Africa, which has been a crossroads of movement between populations from subsahara and Africa, the Arabian Peninsula, and the Nile corridor for 80:52 Speaker A tens of thousands of years. The elevated Rh negative frequencies in these specific communities likely reflect ancient gene flow from populations carrying the variant, possibly through connections with North African populations predating the Sahara expansion that cut those corridors off 81:10 Speaker A roughly 5,000 years ago. It is a tentative reconstruction and researchers continue to refine it. But it is another reminder that the map of this gene does not follow the borders we're used to looking at. Now step back from the 81:25 Speaker A individual data points and look at the overall pattern again. What do all of these elevated frequency communities have in common? The Bas, the Western Irish, the Scottish Highlanders, the Atlas Berbers, the remnant Guanchi ancestry, the Ethiopian Highland communities. 81:43 Speaker A With a notable exception of the Ethiopian case, which has its own distinct history, they are almost all communities defined by one or both of two characteristics. Geographic isolation that limited genetic exchange with the broader demographic movements of their era and cultural 82:00 Speaker A distinctiveness that reinforce social boundaries even where geographic ones were incomplete. They are the communities that were in various ways and for various historical reasons harder to overwrite. 82:12 Speaker A The genetic resilience is not mystical. It is topographic. It is cultural. It is the entirely logical consequence of being in a place or being a group of people. That the great demographic tides of the Neolithic and Bronze Age moved 82:28 Speaker A around rather than through. But there is one dimension of the modern RH negative distribution that goes beyond geography and history and that touches on something closer to the present. 82:39 Speaker A Something that researchers are actively investigating right now. The people who carry Rh negative blood do not differ from Rh positive people only in the presence or absence of a surface protein on their red blood cells. Increasingly, the evidence suggests that the immune 82:56 Speaker A system organization of Rh negative individuals is measurably different in other ways as well. Ways that may have nothing to do with the reesus protein itself, but that reflect the broader genetic context in which the Rh negative deletion arose and was maintained. 83:13 Speaker A Several research groups studying immune response patterns have noted that populations with high Rh negative frequencies show statistically different responses to certain classes of pathogens, particularly certain parasitic infections compared to Rh positive populations. The relationship between RH status and toxopplasma 83:33 Speaker A Gandhi, a parasitic organism estimated to chronically infect somewhere between one quarter and 1/3 of the global human population, has been one of the more intensively studied of these questions. 83:46 Speaker A Some studies have reported that Rh negative individuals respond differently to toxopplasma infection in terms of behavioral and neurological coralates. 83:56 Speaker A Though this research remains contested and the mechanisms are not clearly established, the point is not to overstate what is currently known which is frankly limited. The point is that the immune system of someone carrying Rh negative blood may be organized 84:10 Speaker A differently in ways that extend beyond the single protein whose absence defines the blood type and that those differences if confirmed would add another layer to the already complex question of why this gene has persisted. 84:23 Speaker A It persists. In other words, not simply because it was sheltered in mountain valleys and on foggy islands. It persists potentially because it carries with it something that continues to have functional significance in the bodies of the people who hold it. What that 84:37 Speaker A significance is and whether it represents an ancient adaptation to a specific environmental challenge that no longer exists or something that remains relevant in the modern immune landscape is one of the truly open questions in this field. Researchers who study it 84:53 Speaker A tend to speak carefully and provisionally as scientists should. But the question itself is not fringe science. It is being asked in peer-reviewed journals by researchers at serious institutions with proper methodology and appropriate uncertainty. 85:09 Speaker A which brings us in a way full circle or close to it because the scientific evidence for what Rh- negative blood actually is, where it actually comes from and what it actually does in the human body is considerably more 85:22 Speaker A interesting and considerably more nuanced than either the dismissive mainstream summary or the more extravagant alternative theories tend to suggest. And the evidence itself, the ancient deoxxyribboucleic acid, the skeletal records, the population genetics, the immunological studies is the part of this story that 85:41 Speaker A most people, even those who are deeply curious about Rh negative blood, have never had a chance to look at carefully and in detail. That is what we're going to do next. pull the evidence apart layer by layer and look at what it 85:54 Speaker A actually says and just as importantly what it does not say and what remains stubbornly durably unresolved. 86:02 Speaker A Because the most honest account of this mystery is one that takes the science seriously enough to sit with its uncertainties rather than rushing past them toward a conclusion that feels satisfying but may not be warranted. The evidence laid out carefully is strange 86:17 Speaker A enough on its own. It does not need embellishment and it is far more interesting than most people realize. 86:25 Speaker A Before we go any further, let me tell you what it actually takes to read the genetic record of a person who died 10,000 years ago. Because most people when they hear the phrase ancient deoxyriboucleic acid analysis picture something like a 86:39 Speaker A medical lab, clean surfaces, white coats, orderly rows of equipment. The reality is stranger, more painstaking, and in some ways more dramatic than that. The laboratory where this work happens is maintained at a level of cleanliness that makes a standard 86:55 Speaker A hospital operating theater look relaxed by comparison. The air is filtered constantly. The researchers who work inside wear full body suits, gloves, and face shields, not to protect themselves from the samples, but to protect the samples from them. Because the threat is not 87:11 Speaker A contamination coming in. It is contamination going out. Every modern human being sheds thousands of skin cells every hour. And each of those cells contains deoxxyribboucleic acid that is genetically similar to but not identical with the material being extracted from ancient bone. A single 87:32 Speaker A sneeze in the wrong direction could corrupt a sample that took months to locate, excavate, and prepare. So the researchers move carefully. They speak quietly. They treat the past with a kind of reverence that the past in these rooms has earned. The bone itself, 87:49 Speaker A typically the petrus part of the temporal bone, which is the densest bone in the human skull and therefore the best preserver of genetic material over millennia, is drilled carefully and the powder is collected. 88:02 Speaker A From that powder, through a process involving chemical extraction, enzyatic treatment and amplification techniques refined over the past three decades, researchers attempt to recover fragments of deoxxyribboucleic acid that may be thousands of base pairs long, at most often degraded into much 88:21 Speaker A shorter pieces and present in quantities that would have been undetectable with any technology available before the 1990s. 88:30 Speaker A When it works, what you get is a partial or sometimes nearly complete genome of someone who lived and died before writing existed, before cities existed, before most of what we think of as history had yet begun. When it does not 88:45 Speaker A work, and it often does not, particularly for samples from warm or humid environments where organic material degrades faster, you get nothing. Years of effort and considerable funding and nothing. The person who did more than anyone else to make this field possible is a Swedish 89:01 Speaker A geneticist named Fantabo who spent decades developing the methods for extracting and sequencing ancient deoxyribboucleic acid from Neanderthal remains before broadening his work to encompass the full landscape of ancient human genetics. 89:19 Speaker A In 2022, PBO was awarded the Nobel Prize in Physiology or Medicine for that body of work, the first Nobel ever awarded for ancient genomics, and a recognition long overdue in the estimation of most researchers in the field. His personal 89:36 Speaker A journey to that prize involved years of working in near secrecy on bones that other paleontologists had written off as genetically dead developing techniques that colleagues initially doubted would yield anything useful and eventually producing the first sequenced Neanderthal genome in 2010. A result 89:54 Speaker A that sent shock waves through the anthropological community and changed our understanding of human prehistory in ways that are still being worked out today. One of the things Pabbo's team established, and this matters directly to the question we have been following 90:08 Speaker A through this entire story, is what Neanderthal blood actually looked like genetically. And the answer contains a finding that resolves one of the more widespread alternative theories about Rh- negative blood, though you would not know it from the way the theory 90:22 Speaker A continues to circulate. The theory goes like this. Rh negative blood is evidence of Neanderthal ancestry because modern humans interbreed with Neanderthalss after leaving Africa and Rh negative carriers are the descendants of that interbreeding set apart from the rest of 90:39 Speaker A humanity by their partial Neanderthal heritage. It is a compelling story. It has been told in countless books and internet discussions and it appeals to people for reasons that are not hard to understand. It gives Rh negative blood an origin, a drama, a sense of ancient 90:57 Speaker A differentness that feels proportional to the mystery. The problem is that the ancient genomic evidence does not support it. Neanderthal red blood cells as reconstructed from their genome carried their own version of blood group antigens, including what appears to be a 91:14 Speaker A functional reesus protein complex consistent with being RH positive. The absence of the RHD gene, the deletion that defines modern Rh negative blood, is not present in Neanderthal genetic material, is currently analyzed. 91:30 Speaker A A 2004 study examining blood group Losi and Neanderthal remains, and subsequent work building on PBO's more complete Neanderthal genomic data found no evidence that Neanderthalss carried the specific deletion on chromosome 1 that produces Rh- negative blood in modern 91:47 Speaker A humans. The Dennisovvens, the third archaic human population whose genome was recovered from a fingerbone found in a Siberian cave, similarly show no evidence of carrying the Rh negative variant. This does not mean Neanderthal ancestry is irrelevant to modern human 92:04 Speaker A genetics. It is not irrelevant at all. Most people of non-African descent carry between 1 and 4% Neanderthal ancestry, a finding that has transformed how we think about the relationship between archaic and modern humans. But the specific claim that Rh negative blood is 92:22 Speaker A a Neanderthal inheritance appears to be based on the available evidence incorrect. The deletion that produces it arose in a modern human population after the split from Neanderthalss and its story belongs entirely within the history of Homo sapiens. So where 92:38 Speaker A precisely does the ancient genomic evidence place it? Here the picture becomes more granular and more interesting when you look at specific skeletons rather than population averages. Let me walk you through a few. 92:50 Speaker A The loshbbor skeleton found in a rock shelter in Luxembourg and dated to approximately 8,000 years ago was one of the first western huntergatherer individuals to have his genome sequenced to meaningful coverage. The analysis published in a landmark 2014 paper by 93:06 Speaker A Lazerodus and colleagues that helped establish the three population model of European genetic origins revealed a genome with characteristics typical of the ancient forager populations that preceded farming in Western Europe. 93:19 Speaker A When researchers subsequently examined the loshbbor genome for blood group markers, the findings were consistent with a profile carrying characteristics of the ancient hunter gatherer lineage, including evidence pointing toward the Rh negative region of chromosome 1. The analysis is not definitive enough to 93:38 Speaker A state his blood type with clinical certainty, but it contributed to the broader pattern that has emerged across multiple specimens from the same period and region. More recently and more dramatically comes the case of Cheddar Man, a skeleton discovered in Guff's 93:52 Speaker A Cave in Somerset, England in 1903 and dated to approximately 10,000 years ago, making him one of the oldest nearcomplete skeletons ever found in Britain. 94:04 Speaker A In 2018, a team of researchers from University College London and the Natural History Museum managed to extract sufficient genetic material from Cheddam's inner earbone to reconstruct significant portions of his genome. The results made international headlines primarily because they indicated that 94:22 Speaker A Cheddaman almost certainly had dark brown to black skin, dark curly hair, and blue or green eyes. A combination that most people find surprising when applied to the earliest known Britain, and that generated considerable media commentary about assumptions regarding 94:38 Speaker A the appearance of ancient Europeans. Less discussed in the popular coverage was what the cheddar man genome suggested about his blood markers findings that fit consistently with the western hunter gatherer pattern emerging from sites across the continent. One of 94:53 Speaker A the most genetically informative of all ancient European specimens is a skeleton from Sweden designated Gawk 4, dating to approximately 5,000 years ago and representing a Neolithic period individual with substantial huntergatherer ancestry that had survived the demographic transition occurring elsewhere on the continent. 95:16 Speaker A The Gawk 4 genome has been analyzed in multiple studies as a reference point for understanding the persistence of western huntergatherer ancestry in Scandinavian populations and its blood group region analysis has been cited in several papers examining the ancient 95:31 Speaker A distribution of the RH negative variant. The specimen is not famous outside specialist circles. It does not have a romantic cave discovery story or a celebrity reconstruction, but within ancient genomics, it is quietly one of the more useful data points for tracing 95:49 Speaker A the specific gene we have been following. Here is something worth pausing on because it complicates the simple narrative in an interesting way. 95:57 Speaker A Even within western hunter gatherer populations, the RH negative frequency was not uniform. Specimens from the Atlantic fringe, the Iberian Peninsula, the British Isles, the Francoantabrian region show higher frequencies of the associated markers than specimens from the eastern range of western 96:17 Speaker A huntergatherer distribution in areas closer to the Ukrainian steps and the Balkans. This suggests that the gene was not evenly distributed even among the ancient huntergatherer populations that were its primary carriers. that there may have been a gradient with the 96:32 Speaker A highest concentrations concentrated precisely in the westernmost refugeia that we have already identified as the zone of maximum preservation which is to say the ancient deoxy ribboucleic acid record and the modern population distribution are telling the same story from different ends of time. 96:50 Speaker A Let me be specific about what the ancient genomic evidence as of the most recent and comprehensive analyses can and cannot tell us. On the side of what it can confirm, it places the RH negative deletion firmly within western 97:03 Speaker A huntergatherer populations as a significant frequency variant with estimates clustering between 18 and 26% depending on the study and the specific geographic subset being analyzed. It confirms that Neanderthal and Denisavon populations did not carry the deletion in any form identifiable from current 97:25 Speaker A data. It confirms that the Anatolian and Levventine farming populations who began entering Europe roughly 8 to 9,000 years ago carried the deletion at much lower rates. And it confirms that wherever western hunter gatherer ancestry survived at higher proportions in 97:41 Speaker A post-neolithic European populations. The frequency of Rh negative blood tracked with it behaving like a passenger on an ancient genetic vehicle that retained its distinctiveness wherever the vehicle itself survived. What the ancient genomic evidence cannot tell us, and this is equally important to say clearly 97:59 Speaker A is precisely when the deletion first arose. The window of 35,000 to 40,000 years is a probabilistic estimate based on molecular clock calculations and the oldest specimens in which the relevant markers have been tentatively identified. 98:15 Speaker A The actual origin event, the specific individual in the specific population in the specific environment where the deletion first occurred and began spreading is not recoverable from current data. It may never be. The archaeological record from that period is too sparse and the deoxyriboucleic 98:33 Speaker A acid preservation from specimens that old is rarely sufficient for the kind of detailed analysis that would be needed. 98:40 Speaker A The ancient genomic evidence also cannot tell us why the deletion spread. It can confirm that it did spread that it was present at meaningful frequencies in the populations we have discussed. But natural selection leaves fingerprints in genomes only under specific 98:55 Speaker A circumstances. And the signal for the Rh negative deletion has been difficult to read clearly enough to determine whether its spread was driven by selective advantage by chance. What geneticists call genetic drift or by some combination of both. That question, the 99:12 Speaker A why, not just the what, is one that the evidence opens rather than closes. And it is, I think, the most interesting question of all, not just scientifically, but in terms of what it means for how we understand the people 99:25 Speaker A who carried this gene through the ice age, through the Neolithic upheaval, through the royal courts and the mountain refugeia and the Atlantic coastlines and into the present. Because any explanation for why the deletion survived has to account for all of that. 99:41 Speaker A for 30,000 years of persistence in the face of demographic pressure, biological cost, and the relentless diluting mathematics of population mixing. 99:51 Speaker A Whatever kept this gene alive was not trivial, which is why the competing theories about its origin and persistence matter, and why they deserve to be examined more carefully and more fairly than they usually are. Each of them is trying to answer the same 100:05 Speaker A question. Each of them has something to offer and none of them as of right now has the whole answer. 100:12 Speaker A Every great mystery eventually produces a field of competing explanations. And the more stubbornly a mystery resists resolution, the more varied those explanations tend to become, ranging from the rigorously scientific to the philosophically speculative to the outright mythological with a great deal 100:29 Speaker A of fascinatingly contested territory in between. The question of why RH negative blood exists and why it persists is in this regard no different from any other deep human puzzle. It has attracted serious scientists, careful historians, imaginative theorists, and passionate 100:48 Speaker A believers, each approaching the same set of facts with different frameworks and arriving at conclusions that sometimes barely resemble each other. What I want to do here is something that is in practice harder than it sounds. present four of the most significant explanatory 101:04 Speaker A frameworks as fairly as possible, including the ones that most academic scientists would not touch with a 10-ft pole and then let you sit with the evidence and make your own assessment. I have my own views and I will share some 101:17 Speaker A of them. But I'm much more interested in giving you the tools to think about this clearly than in telling you what to conclude. So, four theories, one blood. 101:26 Speaker A Let's be careful with all of them. The first is the one that most professional geneticists would call the default position and it goes by the somewhat unglamorous name of genetic drift. The idea is this. The Rh negative deletion 101:41 Speaker A arose as a random mutation in a specific population roughly 35 to 40,000 years ago which we established from the ancient genomic record and then spread through that population not because it offered any survival advantage but simply because of the mathematics of 101:57 Speaker A small groupoup genetics in a population of a few hundred or a few thousand individuals which is what most ice age hunter gatherer bands would have been random fluctuations in gene frequency can can be quite dramatic. A gene present in 20% of one generation might 102:13 Speaker A climb to 35% in the next purely by chance simply because the individuals who happen to survive and reproduce in that generation slightly over represented carriers of that variant over many generations. This process called genetic drift can cause gene 102:30 Speaker A frequencies to rise or fall in ways that have nothing to do with whether the gene helps or harms. And in very small isolated populations, the effect is amplified. A founding group of 50 people carries only the genes that those 50 102:45 Speaker A people happen to have. If three of them carried a specific deletion, that deletion is suddenly 6% of the founding gene pool, not because it was selected for, but because those three people were among the lucky few who survived 102:58 Speaker A whatever bottleneck created the founding group. The genetic drift model is quite good at explaining certain aspects of the RH negative distribution. The concentration in isolated Atlantic fringe populations is consistent with what you would expect from a gene that 103:14 Speaker A was relatively common in the ancestral western huntergatherer population and then got preserved by bottlenecks. The Pyrenees, the Irish Sea, the Scottish Highlands that isolated subsets of that population from the diluting effects of later migrations. The near absence in 103:31 Speaker A East Asia and subsahara and Africa is consistent with those populations having diverged from the ancestral lineage before the deletion arose or before it had spread to their founding populations. The model is parimonious which scientists like. It does not 103:47 Speaker A require exotic mechanisms. It just requires time small groups and the cold mathematics of probability. Where it runs into trouble is with the persistence problem. Genetic drift is equally good at eliminating genes as at spreading them. A gene that carries a 104:04 Speaker A real biological cost and hemolytic disease of the newborn is a real biological cost as we have seen should over tens of thousands of years drift downward towards zero. 104:15 Speaker A The fact that the gene is still present at 15% globally and at 35% in some populations requires either extraordinary luck across an enormous span of time or some counterbalancing pressure that kept it from drifting away. The drift model cannot fully 104:31 Speaker A explain that and that gap is where the second theory steps in. The selective advantage hypothesis, sometimes called the parasite resistance hypothesis, in its more technical formulations, argues that the RH negative deletion persisted because under at least some historical 104:47 Speaker A environmental conditions, it provided its carriers with a meaningful survival benefit that offset the reproductive cost imposed by hemolytic disease. 104:57 Speaker A The candidate mechanisms vary, but the one that has attracted the most sustained and serious scientific attention is the relationship between RH status and toxopplasma Gandhi. You may remember that name from earlier in our story. A single-sellled parasite that 105:13 Speaker A infects the brain tissue of mammals that is estimated to chronically affect somewhere between 1/4 and 1/3 of the global human population, typically without causing obvious illness in healthy adults, but producing subtle neurological and behavioral changes that researchers are still working to 105:32 Speaker A characterize fully. The scientist who has spent the most time and professional risk on this specific question is a Czech evolutionary biologist named Jaruslav Fleer based at Charles University in Prague. Fleeer began publishing research on the behavioral effects of toxopplasma infection in the 105:50 Speaker A mid 1990s at a time when most of his colleagues considered the idea that a brain parasite could meaningfully alter human behavior to be somewhere between eccentric and actively ridiculous. 106:03 Speaker A Over the following two decades, as the broader scientific community gradually came to take the toxopplasma behavior connection more seriously, Fleer and his collaborators turned their attention to a specific question. Do Rh negative individuals respond differently to toxopplasma infection than Rh positive 106:23 Speaker A individuals? His research published across a series of papers found evidence suggesting that yes, they do that. Rh negative individuals appear to show different patterns of certain psychological and behavioral coralates associated with toxopplasma infection in ways that suggest their immune response to the 106:42 Speaker A parasite may function differently. The mechanism is not established. The findings remain contested. Some researchers consider Fleger's work important and underappreciated. 106:55 Speaker A Others consider his methodologies and interpretations insufficiently rigorous. Science in other words is doing what science does arguing carefully in the direction of truth. The selective advantage hypothesis does not live or die on the toxopplasma question alone. 107:12 Speaker A There are researchers who have examined Rh status in relation to other pathogens, other environmental pressures and other aspects of immune function. 107:21 Speaker A The broader picture that emerges tentatively provisionally with all appropriate scientific caveats is that the immune system of an Rh negative individual may be organized differently in ways that produce measurable differences in pathogen response and that those differences may have been 107:38 Speaker A advantageous in the specific ecological environments where the ancient populations carrying the deletion were living. Whether that advantage was large enough to counterbalance hemolytic disease and whether it is specific enough to constitute a clear selective pressure are questions that the evidence 107:56 Speaker A has not yet answered. But the hypothesis is serious. It is being investigated by serious people and it may turn out to be part of the answer. The third framework is less wellknown in popular discussions, but it is one that I find 108:11 Speaker A particularly compelling as an intellectual proposition, and it comes out of a finding in ancient genomics that most people are not familiar with. 108:20 Speaker A In 2016, Yoseseph Lazeritis and colleagues published a landmark study that refined our understanding of the three major ancestry components that make up modern European genomes. The study confirmed the now familiar picture of western hunter gatherers, Anatolian farmers and Yamna step pastoralists. 108:42 Speaker A But it also provided stronger evidence for a fourth ancestral component that researchers had been tracking in earlier analyses and that goes by the name Basil Eurasian. Basal Eurasians as reconstructed from the genomic signal they left in later populations appear to 108:58 Speaker A have been a lineage of modern humans that diverged from the rest of the non-affrican homo sapiens population at some point between 45,000 and 55,000 years ago earlier than the divergence of any other population that contributed to modern Europeans and that lived in 109:15 Speaker A isolation somewhere in the Middle East or North Africa for many thousands of years before mixing with other groups during during the Neolithic period. The intriguing possibility, and I want to be clear that this is a hypothesis, not an 109:28 Speaker A established finding, is that basil urasians may have been one of the populations where the Rh negative deletion arose and was maintained in relative isolation at elevated frequencies before mixing with other lineages, reintroduced it into the broader genetic landscape of Western 109:45 Speaker A Eurasia. The basal Eurasian signal is strongest in early Neolithic populations from Iran and the Levant areas where the modern remnant of the ancient western huntergatherer Atlantic fringe also shows some of its most intriguing patterns. 110:03 Speaker A This connection, if it holds up to further analysis, would suggest that the story of RH negative blood is not simply a story of Ice Age Western Europeans, but something older and more geographically complex, a story that begins further east and further back in 110:20 Speaker A a population whose isolation preserved something ancient before the great mixing events of the Holene washed it into the western world. Now, the fourth framework, and here is where I want to be especially careful, not because it is more dangerous to discuss than the 110:36 Speaker A others, but because it is easier to discuss carelessly and careless discussion in either direction does it a disservice. Across multiple ancient cultures, there exist traditions that describe certain lineages of human beings as set apart from the rest as 110:52 Speaker A carrying something in their nature, their blood or their spirit that differentiated them from the ordinary human population. 111:00 Speaker A In the Hebrew textual tradition, the Nephilim described as the offspring of the sons of God and the daughters of men have been interpreted by some readers across centuries as a reference to a distinct and powerful lineage whose biological heritage was literally 111:15 Speaker A different from that of ordinary humans. In Celtic mythology, the Tuatha de Danan, the divine or semi- divine race said to have inhabited Ireland before the arrival of the Gales, are associated in some traditions with specific physical and temperamental qualities 111:32 Speaker A that set them apart. And certain modern interpreters have linked these traditions to the elevated RH negative frequencies found in Irish and Scottish populations descended from the oldest inhabitants of those islands. 111:46 Speaker A In the ancient Sumerian texts, the literary corpus that predates the Hebrew Bible by thousands of years and that provided some of its probable source material. There are references to the Anunnaki, a class of divine or semi- divine beings whose interactions with 112:03 Speaker A humanity left marks in both the physical and spiritual lineage of the human race. I am not telling you these traditions are literally true in any of the specific ways they are sometimes presented. What I am telling you is that 112:15 Speaker A they are old and that they are widespread and that the impulse behind them, the sense that something real and biological distinguishes certain human lineages from others in ways that are not fully explicable by ordinary inheritance is itself worth taking 112:31 Speaker A seriously as a cultural data point. When human beings across multiple cultures with no contact with each other independently develop traditions describing a distinct and ancient bloodline among them, the pattern of belief is itself a fact about human history that requires explanation. 112:51 Speaker A The ancient populations who carried Rh negative blood at the highest frequencies were by the genetic evidence measurably different in biological ways from the population surrounding them. 113:03 Speaker A They had different immune systems. They were the remnants of an older Europe. They spoke languages no one else could understand. They maintained traditions and social structures that their neighbors did not share. Whether or not any of the mythological frameworks are 113:17 Speaker A literally correct, they are culturally plausible responses to a biological reality that people could perceive without being able to name. Which brings me to the position I have settled into after spending a long time with all four of these frameworks. For whatever my 113:32 Speaker A position is worth, I suspect the answer to why RH negative blood exists and persists is not one of these theories. I suspect it is some combination of all of them. That genetic drift explains the initial spread and the geographic 113:48 Speaker A patterning that some form of selective advantage explains the persistence against biological cost. that the basal Eurasian or similar isolated lineage story explains some of the deeper origins and that the cultural traditions encode in the language available to ancient people a genuine perception of 114:07 Speaker A biological distinctiveness that modern genetics is only now giving us the vocabulary to describe precisely none of that is a tidy conclusion but very few of the most interesting questions in human history resolve into tidy conclusions what they resolve into if we are patient 114:24 Speaker A and honest with them is a richer and more complicated picture of what human beings are and where they have been. And speaking of where they have been, the consequences of this particular blood type did not play out only in caves and 114:37 Speaker A royal palaces and genetics laboratories. They played out in households, in the quiet arithmetic of families that grew and shrank and grew again across centuries shaped by biological forces that nobody in those families could see or name. that domestic history, the 114:54 Speaker A human scale history of Rh negative blood and the pregnancies it complicated the families it shaped and the social structures it may have silently influenced is where this story goes next. Somewhere in a stone church in Normandy in the year 1247, a priest sat 115:09 Speaker A down with a quill and a ledger and recorded what had happened in his parish that year. He wrote the names of those who had married. He wrote the names of those who had been born. and he wrote in 115:20 Speaker A the patient and careful hand of a man who had learned to treat death as administrative necessity the names of those who had not survived their first winter. It was not unusual work. Every parish priest in medieval Europe kept 115:33 Speaker A such records and every such record tells if you know how to read it two stories simultaneously. The one the priest intended and the one hidden inside the numbers. Historians who have studied French parish records from the medieval and early modern periods have noted with 115:48 Speaker A increasing frequency as the documentary record has become more accessible and the analytical tools more sophisticated that certain villages show patterns of infant mortality that cannot be explained by the general background rates of preodern child death. In some communities, particularly those in 116:07 Speaker A isolated highland regions in areas with documented long- settled populations and limited in migration, the pattern of infant death has a specific shape. First children survive at relatively normal rates. Second and third children die at elevated rates. Fourth and fifth 116:26 Speaker A children, when they come, sometimes survive again, particularly if several years have elapsed since the previous pregnancy. And the women at the center of these patterns sometimes watch multiple pregnancies end the same way without apparent cause. While their neighbors whose families show none of 116:41 Speaker A these patterns look on with a mixture of pity and theological explanation, medieval physicians and theologians had a rich vocabulary for this kind of tragedy. The terms varied by region and era. Cursed blood, incompatible humors, constitutional weakness, the punishment 116:58 Speaker A for sins committed before marriage or inherited from distant ancestors. None of these frameworks were correct. But they were not entirely without logic either because the physicians and priests who developed them were observing real patterns. The patterns were real only the explanations were 117:16 Speaker A wrong. What I want to explore in this part of our story is something different from the mechanics of what happens biologically. We covered that ground earlier. What I want to explore is the downstream effect. What does it mean for 117:28 Speaker A a community when a significant fraction of its women face reproductive difficulties of this specific kind across multiple generations without anyone understanding why? How does that shape family structure inheritance? The role of women in community life, the economics of households, the cultural 117:46 Speaker A practices that develop around childbirth and loss. These are questions that historians rarely ask through the lens of blood type. And I think the answers, even partial and speculative as they must be, are illuminating. Consider Iceland. It is on the surface an 118:02 Speaker A unlikely place to find relevant evidence. a volcanic island in the North Atlantic, first settled by Norse Vikings beginning around the year 874. 118:12 Speaker A But Iceland has two things that make it invaluable for this kind of inquiry and unusual genetic history and an extraordinary documentary record. The genetic history is the product of the founder effect. The island was colonized by a relatively small group of settlers, 118:28 Speaker A primarily from Norway, but with a significant contingent of Gaelic speaking people from Ireland and Scotland, whose descendants make up essentially the entire modern Icelandic population. 118:41 Speaker A Because the island remained relatively isolated for most of its history, the modern Icelandic gene pool reflects that founding population with unusual clarity, including its frequencies of various blood types. Icelandic RH negative frequencies run at approximately 15 to 16% consistent with 119:00 Speaker A the Norse and Gaelic ancestry of the founding population and substantially elevated compared to continental European averages outside the Atlantic fringe. The documentary record is the Islandingabok, the book of Icelanders, which is arguably the most detailed genealogical database in the world. 119:18 Speaker A Originally compiled in the 12th century by a scholar named Arie Thorgillson and expanded into a modern digital database covering more than 700,000 individuals across the entire documented history of Icelandic settlement. It allows researchers to trace family lines, reproductive outcomes, and demographic 119:37 Speaker A patterns across dozens of generations in ways that are impossible in most other populations. Geneticists and medical researchers have used the Aslending Abok for everything from tracing hereditary disease patterns to studying the demographic consequences of volcanic eruptions and famine events. 119:56 Speaker A And while no study has yet used it specifically to map the historical consequences of RH incompatibility across Icelandic family lines that analysis as of the most recent research remains to be done. The database exists. 120:11 Speaker A The data is there and the research tools to interrogate it in precisely this way are now available. It is in a sense waiting for someone to ask the right question. The communities that did not have Iceland's documentary luck which is 120:24 Speaker A most of them left their evidence in different forms in the Basque country where the intersection of high RH negative frequency and unusually detailed local social history creates a particularly rich research context. 120:39 Speaker A Anthropologists working in the 20th century collected oral traditions from rural communities that described in the folk language of those communities what sounds remarkably like a recognizable pattern of reproductive loss. The specific terms varied by valiant village. Some communities spoke of 120:58 Speaker A families with blood that did not agree with itself. Others described women who were considered with neither cruelty nor censure but simply as a practical matter to be unlikely to raise more than one or two children successfully and who were 121:12 Speaker A accorded a particular kind of status in the community on that basis. One that compensated for reproductive limitation with other forms of social authority. 121:21 Speaker A These oral traditions collected and recorded by researchers before the communities that held them had been fully absorbed into the modern world were not interpreted at the time as having anything to do with blood type. 121:33 Speaker A They were filed under folklore. But read from the perspective of what we now know about Rh incompatibility. 121:40 Speaker A They describe it with uncomfortable accuracy. The question of whether RH incompatibility shaped social structures in RH negative concentrated communities is one that historians have only begun to take seriously and the evidence is suggestive rather than conclusive. But several lines of observation point in a 121:58 Speaker A consistent direction in communities with elevated RH negative frequencies. Basque western Irish certain Scottish Highland groups. 122:09 Speaker A Historical family sizes in the premodern period tended to be smaller than in comparable communities with lower RH frequencies. The effect is not dramatic enough to be obvious in any single generation, but across multiple generations. And at the population 122:25 Speaker A level, it produces a measurable difference. Smaller completed families mean different inheritance dynamics. They mean that daughters are more likely to inherit property because there are fewer sons competing for it. They mean that women who successfully raise children to adulthood hold unusual 122:43 Speaker A status because the outcome is less certain than in populations where reproductive loss was less common. They mean that the community develops over time practices and customs calibrated to the reality of its reproductive experience whether or not anyone ever 122:58 Speaker A articulates that calibration explicitly. The anthropologist Julio Caro Baro Roja, who spent decades studying Basque social history in the midentth century, documented in painstaking detail the unusual degree of household authority exercised by women in traditional Basque communities, their control over domestic 123:18 Speaker A finances, their central role in religious observance, their legal standing in property matters that exceeded what was typical in contemporary European societies. 123:29 Speaker A Caro Bar Roa attributed this to cultural continuity with pre-indo-uropean social norms which is almost certainly part of the explanation. But I find myself wondering whether the biological reality of Rh incompatibility playing out silently across generations, making the successful raising of 123:48 Speaker A multiple children a less predictable outcome than it was for neighboring populations may have reinforced and sustained those social norms in ways that went beyond pure cultural tradition. A community that loses children more often develops different ideas about the value and authority of 124:05 Speaker A the mothers who managed to raise them. That is not a mystical claim. It is a sociological observation. There is a comparison that I think is worth drawing out even though it is speculative and should be treated as such. In the 124:19 Speaker A centuries before and after the Norman conquest of England in 1066, the documentary record allows historians to compare in at least broad terms the demographic patterns of Celtic communities in Western Ireland and the Anglo Norman settlements that arrived in 124:34 Speaker A the same period. The Celtic communities of the western coast areas where RH negative frequencies by modern measurement run significantly higher than the Angloorman influenced east show patterns in their genealogical records in the few cases where those records survive that suggest 124:52 Speaker A smaller average family sizes longer gaps between recorded births and higher rates of what the records describe as infant death without specified cause. 125:03 Speaker A The Anglo Norman settlements drawing their founders primarily from the more RH positive dominant populations of France and land England show somewhat different patterns. The comparison is imperfect record survival is unequal. 125:17 Speaker A The time frames are not always comparable and confounding factors are numerous, but it is not nothing. What the comparison points toward again tentatively is that the biological fact of RH incompatibility may have been one of several factors that shape the distinctive social and 125:34 Speaker A demographic character of the Atlantic fringe Celtic communities. Not the only factor, not even necessarily the primary factor, but a real one. an invisible hand that helped shape household structures, inheritance practices, the status of women, the size of families, 125:52 Speaker A and the cultural weight placed on the children who did survive. All without any of the people living through it, having the faintest idea what was actually happening in their blood. A study of Basque family records from the Gipusa and Biskaya provinces conducted 126:06 Speaker A by demographic historians in the 1970s and drawing on church registers going back several centuries found that average completed family size in rural Basque communities during the early modern period ran between three and four children lower than the European average 126:21 Speaker A of the same period which was closer to 5 to six surviving children per family. 126:27 Speaker A The researchers attributed the difference primarily to later marriage age among Basque women and to specific inheritance customs that delayed household formation. Both of those explanations are valid and documented. 126:40 Speaker A But the biological dimension, the one that would have quietly increased the rate of second and third child loss in families where the mother was Rh negative and the father was Rh positive, was not a variable. The researchers of 126:54 Speaker A the 1970s had any particular reason to include in their models. It was not on anyone's radar as a demographic force. 127:02 Speaker A It is only now with both the ancient genomics and the modern clinical understanding of Rh incompatibility available simultaneously that the full picture begins to come into focus. 127:13 Speaker A Perhaps the most important thing to understand about RH incompatibility as a historical force is precisely its invisibility. 127:22 Speaker A It did not announce itself. It did not cluster visibly in certain families in ways that would have been legible to observers. It looked from the outside exactly like the ordinary tragedy of preodern child death, indistinguishable from infection, from malnutrition, from 127:39 Speaker A the hundred other causes that took children before their first birthday in a world without modern medicine. only its pattern, the specific sequence of survival and loss, the way it compounded with each pregnancy, the way it spared first children and took later ones 127:54 Speaker A distinguished it. And that pattern was real documented in parish records and oral traditions and genealogical databases, waiting for someone with the right tools to read it for what it was. 128:06 Speaker A That invisibility is in its own way a kind of historical injustice. The women who lived through it were resourceful, resilient, and in many cases, exceptional managing households, maintaining traditions, holding communities together under conditions of repeated loss that most of us in the 128:24 Speaker A comfort of modern medicine can barely imagine. Their biology was not their identity, but it was in ways they could not see. And we only now beginning to trace a force that shaped the world they lived in. That shaping did not end with 128:38 Speaker A the past. It continues in transformed, more visible and considerably less tragic forms into the present day. And the present- day story of RH negative blood in a world where its biological costs have been largely removed by medicine is one of the most unexpectedly 128:55 Speaker A interesting chapters in this whole account. In the winter of 2021, as hospitals across the United States were managing the worst surges of the pandemic, blood banks reported something that had nothing to do with the virus itself, something that had been quietly building 129:13 Speaker A for years and that the disruption of normal donation patterns had pushed to a critical threshold. The American Red Cross declared a national blood crisis. 129:23 Speaker A Supply had fallen to its lowest levels in over a decade. And within that general shortage, one blood type was in particularly acute demand, O negative. 129:33 Speaker A The Red Cross described the situation as dire. Trauma centers were rationing neonatal intensive care units where a negative blood is often the only option for emergency transfusions in newborns whose blood type cannot be quickly determined were operating on reserves 129:49 Speaker A measured in hours rather than days. The shortage passed as shortages do through urgent public appeals and a temporary surge in donation drives. But it illuminated something that most people who have never needed an emergency transfusion do not think about. The 130:05 Speaker A entire architecture of emergency medicine is quietly built around the assumption that O negative blood will be available. In any mass casualty event, a major accident, a natural disaster, a military engagement, O negative blood is the first thing deployed because it can 130:22 Speaker A be transfused into any patient regardless of their blood type without taking the time for compatibility testing that standard typed blood requires. It is in the operational language of emergency medicine, the thing you reach for when there is no 130:35 Speaker A time to reach for anything else. O negative blood represents approximately 6 to 7% of the general population in the United States and Western Europe. The gap between how often it is needed and how often it naturally occurs in the 130:48 Speaker A donor pool is one of the structural vulnerabilities of modern blood supply chains. A vulnerability that has existed since blood banking became systematized in the 1940s and that has never been fully resolved. Blood banks use algorithms to manage it. Hospitals 131:05 Speaker A maintain reserve protocols. Military medical units trained specifically around the scarcity. And none of it is quite sufficient because the demand particularly in mass casualty scenarios consistently outpaces the supply. What most people do not know is that military medicine has been grappling with this 131:24 Speaker A specific problem for longer than civilian hospitals have. During the Second World War, as military blood banking was being developed almost from scratch by researchers like Charles Drew, whose work establishing blood plasma preservation techniques fundamentally change trauma care. The 131:42 Speaker A practical problem of blood type compatibility in field conditions was a constant operational concern. The solution that field surgeons often fell back on was to identify soldiers who were O negative within their units and treat them informally as walking 131:57 Speaker A reserves, a practice that continued in more organized form into later conflicts. The United States military's current program for managing emergency blood supply in combat theaters, sometimes called the walking blood bank protocol, formalizes this practice, maintaining registers of blood type 132:16 Speaker A service members who can serve as emergency donors when stored blood supplies are unavailable. O negative individuals occupy a specific and operationally critical role in those registers. their blood in a military context is a resource that gets planned around. The civilian equivalent of this 132:33 Speaker A planning is quieter but no less real. The National Rare Blood Club established in the United States in the 1990s maintains a registry of donors with rare blood types, a category that includes not just O negative but individuals whose blood lacks multiple common 132:51 Speaker A antigens simultaneously making them compatible donors for a very small number of potential recipients. When a rare blood type is needed urgently, these registries activate through direct contact, a phone call, a text message to individuals who have agreed to be available as donors on 133:08 Speaker A short notice. It is a remarkably intimate system for something that operates at national scale, a network of specific people known by name whose particular biological inheritance makes them valuable in ways they did not choose and cannot replicate through any 133:24 Speaker A amount of effort or training. The blood is simply what it is, and occasionally what it is turns out to matter enormously to someone who would otherwise have no options. There is something about this that I find quietly remarkable. And I do not mean remarkable 133:40 Speaker A in any mystical sense. Just in the plain human sense of here is an ancient genetic trait 35,000 years old by the best estimates carried by a small fraction of the population shaped by ice ages and population migrations and the 133:56 Speaker A slow arithmetic of demographic history. And today it is sitting in a database somewhere being matched to a trauma patient in an emergency room who does not know and may never know anything about the person whose blood is about to 134:09 Speaker A save their life. History does not usually reveal itself so directly. This is an exception. Shift now from the emergency room to the classroom specifically to classrooms in the Basque country where something that was considered a lost cause as recently as 134:24 Speaker A 40 years ago is now compulsory. Yusker the ancient language whose impossible grammar and vocabulary we trace through the genetics and the prehistory of Western Europe came close to functional extinction in the midentth century. 134:40 Speaker A Under Francisco Franco's dictatorship which lasted from 1939 to 1975 the use of Basque in public was suppressed schools conducted classes exclusively in Spanish public signage was in Spanish and the speaking of Yuscara in official context carried real social risk. By the 135:00 Speaker A time Franco died and Spain began its transition to democracy, the number of fluent Basque speakers, particularly among younger generations, had dropped to levels that linguists considered dangerously close to the threshold from which languages do not recover. The recovery that followed is by any measure 135:18 Speaker A one of the more remarkable stories in modern linguistic history. through a combination of political will community organization and an educational network called the Ikastola Basque medium schools that were originally run illegally during the Franco years and then formalized after democratization. 135:37 Speaker A Yuscara not only survived but expanded. Today roughly 700,000 people speak Basque with meaningful fluency and the number has been growing steadily for two decades. Basque is now a compulsory subject in schools across the Basque autonomous community. There is Basque 135:56 Speaker A language television, Basque language social media, Basque language literature produced by writers who are born into a world where their languages survival was not guaranteed. Why does this matter to the story we've been telling? Because Yuscar is, as we established earlier, 136:12 Speaker A not just a language. It is a marker of genetic and cultural continuity with a prenolithic past and its revival is happening alongside in some ways in deliberate conversation with a renewed interest in what Basque identity means at the deepest level including at the 136:30 Speaker A biological level that modern genomics has made suddenly legible. Young Bas are taking ancestry tests in numbers comparable to the United States and the United Kingdom. They are finding in the results confirmation of what the oral traditions of their communities have 136:47 Speaker A always asserted that they are something old, something distinct, something that has been here longer than almost anything else in European recorded memory. Whether that confirmation changes how they move through the world is a question that anthropologists are beginning to study and that I suspect 137:03 Speaker A will produce interesting answers over the next generation. The same phenomenon in different forms is playing out in Ireland and in Scotland. The Irish language and Gale gay has seen enrollment in Gail Skoana Irish medium schools grow by more than 40% over the 137:19 Speaker A past two decades. Scottish Gaelic spoken by fewer than 60,000 people at its low point in the early 21st century has stabilized and begun to show modest growth supported by a television channel, a literary publishing industry, and a government commitment to 137:36 Speaker A preservation that would have seemed utopian 30 years ago. These are, it should be said, small numbers in absolute terms. None of these languages is replacing the dominant tongues of their respective nations anytime soon. But the direction of travel has reversed. Languages that were 137:54 Speaker A dying are stabilizing. Communities that were losing their distinctiveness are in some measure reclaiming it. I'm not suggesting that there is a simple or direct connection between RH negative blood frequencies and Celtic cultural revival. The relationship between genes and culture is neither simple nor 138:14 Speaker A direct. It never is. And anyone who tells you otherwise is oversimplifying. What I'm suggesting is that the same deep roots, the same long history of geographic isolation, cultural distinctiveness and stubborn preservation of older ways that protected elevated RH negative 138:33 Speaker A frequencies in these Atlantic fringe communities are also the roots from which cultural revival is growing. The biology and the culture emerge from the same source. They're expressions of the same underlying persistence. Now, and I say this knowing that it will resonate 138:48 Speaker A with some listeners more than others, and that is entirely fine. There is a modern community phenomenon around Rh negative blood that deserves to be mentioned, even if it sits somewhat awkwardly next to the scientific content we have been working through. Across 139:04 Speaker A social media platforms, there are large active communities of people who identify specifically as Rh negative, who discuss their blood type as a meaningful component of their personal identity, who share experiences they believe are connected to their blood, and who approach the question of what Rh 139:22 Speaker A negative blood means with considerably more certainty than the evidence currently supports. Some of these communities have developed beliefs that go well beyond what the science says. 139:33 Speaker A Some of them have arrived at conclusions that I would not endorse and that the research does not back up. And yet I do not find myself wanting to dismiss these communities even when I disagree with specific claims they make. Because what 139:48 Speaker A they are doing, however imperfectly, however speculatively is trying to locate themselves in a story larger than their individual lives. They're asking, "What am I carrying? Where did it come from? What does it connect me to? These are not foolish questions. They're among 140:06 Speaker A the oldest questions human beings ask. The answers that circulate in those communities are sometimes wrong, sometimes dramatically wrong. But the impulse behind the questions is the same impulse that drives everything we have been talking about for the past several 140:21 Speaker A hours. The desire to understand what is written in our blood and what it means about who we are and where we come from. 140:27 Speaker A The science taken seriously and followed carefully. offers something better than the myths and actual answer, partial and evolving and full of genuine uncertainty, but rooted in evidence that can be examined and questioned and refined. 140:42 Speaker A And that answer, the story of a deletion on chromosome 1 carried by the people who painted the oldest art in the world, preserved in the mountain refugeia of the Atlantic fringe, traced through the parish records and the genealogical 140:56 Speaker A databases and the ancient bones of people who lived and died before history had a name for what they were is, I think, more interesting than any of the myths. Not despite its uncertainty, but partly because of it. Because the 141:10 Speaker A uncertainty is real, and real things carefully examined are always more interesting than invented certainties. 141:17 Speaker A There is one more piece of this story left to tell. Not a new discovery, not a new theory, not a new data point from a laboratory or an archive. Something quieter than that. something that has been waiting at the beginning of this 141:32 Speaker A whole account in the darkness of a cave 32,000 years ago where a hand was pressed against cold stone and a breath of ochre left its mark and did not wash away. That image and what it asks of us 141:46 Speaker A is where this story finds its ending. Go back with me one last time to a cave not to discover it. Not to stand at the entrance with a flashlight trembling in the hand. We have already done that. Go 141:58 Speaker A further in past the entrance chamber, past the first panels where the animals begin to appear deeper into the darkness where the only light that has ever fallen on the walls was firelight orange and alive and trembling held by hands 142:11 Speaker A that have been dust for 30,000 years. Stand there for a moment in the imagined dark. Let your eyes adjust to something that cannot actually be seen and then look at the wall to your left or your right or directly in front of you. 142:24 Speaker A Because in this cave, in this particular stretch of the Francoantabrian limestone world, the choice hardly matters. 142:32 Speaker A Wherever you look, there is something there. Something left deliberately with care by someone who wanted it to remain. 142:39 Speaker A Now look at the hands, not the horses, not the lions, rendered with that almost impossible naturalism that still stops art historians mid-sentence when they try to describe it. The hands pressed flat against the cold stone, a breath of 142:54 Speaker A pigment blown around them, ochre or manganese or charcoal, leaving a silhouette, a negative space in the shape of a living hand that has been gone for an almost incomprehensible span of time. And ask yourself seriously and slowly the question that I have been 143:10 Speaker A circling around since the very beginning of this story. Who was this person and what did they want? Because they did want something. The act of making a handprint, pressing your palm to stone, applying pigment carefully around each finger, stepping back to look at what 143:24 Speaker A you have made is not an accident. It is not the unconscious byproduct of some other activity. It is deliberate precise and the result is unmistakably personal, not a symbol of something larger, not a representation of an animal or a force 143:38 Speaker A of nature or a divine being. Just a hand. My hand. I was here. I existed. 143:46 Speaker A This is the shape of me. The person who made that print may or may not have carried Rh- negative blood. The ancient genomic record, as we have traced it carefully through this story, suggests that the population of western hunter 143:59 Speaker A gatherers who lived and painted in this region during the late Paleolithic, carried the relevant genetic variant at meaningful frequencies somewhere between 1 in five and 1 in four individuals by the best current estimates. Which means that if you were standing in that cave 144:14 Speaker A watching a group of a dozen people come in to work on the walls, two or three of them statistically carried something in their blood that most of the world's population did not and does not carry. 144:25 Speaker A something old, something that had already been in their lineage for tens of thousands of years, passed down through mothers and fathers and children across an unbroken chain of births and deaths, stretching back to whenever we do not know precisely when the deletion 144:40 Speaker A first arose in some specific individual in some specific place that no one will ever be able to identify. That chain has not broken. That is the extraordinary thing. Despite everything, despite the Neolithic revolution that transformed the continent, despite the Bronze Age 144:57 Speaker A migrations that overwrote most of what the Ice Age Europeans had built, despite the demographic tides and the dynastic tragedies and the invisible biological cost that accumulated in the gaps between what people understood and what was actually happening in their blood, 145:13 Speaker A the chain held. It bent. It frayed in some places almost to nothing, but it did not break. And the people who carry Rh negative blood today are in a very literal and measurable sense the living continuation of that chain. The final 145:30 Speaker A link for now in something that began before any civilization we have a name for. I find that remarkable. Not because it makes Rh negative people special in any way that diminishes everyone else. 145:42 Speaker A Every human being alive today is a final link in an equally long and equally improbable chain. The genetic signatures that make up any one person. The ancient farmer from Anatolia. The step pasturalist from the Pontic grasslands. 145:56 Speaker A The coastal fisher from the Atlantic fringe. The subsaharan African forager whose lineage predates all of these by tens of thousands of years are all miracles of continuity in exactly the same sense. All of them made it through. 146:11 Speaker A All of them against odds that get more staggering the longer you look at them managed to pass something of themselves forward into the present. You are the proof that every single one of your ancestors survived long enough to have 146:22 Speaker A at least one child. Everyone all the way back in an unbroken line through famines and floods and plagues and ice ages and everything else that history has thrown at the human species. That is not nothing. That is if you stop and 146:38 Speaker A actually feel the weight of it for a moment. almost everything. What blood remembers is not specific events. It does not carry the memory of a particular winter or a particular loss or a particular moment of joy. What it 146:52 Speaker A carries is something more structural than that. The accumulated decisions of natural selection, the preserved variations of ancient populations, the genetic echoes of environments and pressures and encounters that happened long before any individual consciousness was there to experience them. The RH 147:11 Speaker A negative deletion is one such echo. It is the sound of a world that existed before agriculture, before cities, before writing, before any of the frameworks through which we normally understand human history. 147:25 Speaker A It is in the most literal sense available to biology a message from the past addressed to no one in particular, delivered to whoever happened to carry it. Think for a moment about what that means if you are one of the people who 147:39 Speaker A carries it. You did not choose this. It was not given to you by anyone who understood what they were giving. The chain of transmission that brought this particular genetic variant to your cells is longer and more complex and more 147:52 Speaker A contingent on an almost infinite series of accidents and survivals than any deliberate inheritance could ever be. 148:00 Speaker A And yet here it is in your blood waiting as it has always waited for whatever comes next in the story that is still being written. And think for a moment about what it means if you do not carry 148:12 Speaker A it. If your blood is Rh positive, which is the blood type of the great majority of the people listening to this right now. Your blood carries its own ancient signatures. The expansion of Anatolian farmers who brought agriculture to 148:25 Speaker A Europe. the spread of Yamnia pastoralists who brought the Indo-Uropean languages that became almost every tongue spoken in the Western world today. 148:35 Speaker A The migrations out of Africa that began this whole story 60,000 years ago or more when the first modern humans walked into a world they would slowly over countless generations come to fill. 148:47 Speaker A Every blood type is ancient. Every blood type is a record. The difference is only in which records are preserved in which people and the fact that we can now for the first time in human history actually read some of those records. That 149:02 Speaker A readability is new. The writing has always been there. What is new is our ability to see it. And I think that ability, the capacity to look into the deep past of our own biology and find something actual and specific and 149:16 Speaker A traceable changes something in how we understand ourselves. Not dramatically, not overnight, and not in ways that are easy to articulate, but something shifts. The sense that we are isolated individuals, a drift in a historical moment without roots or context or 149:34 Speaker A continuity. That sense, which is a very modern kind of loneliness softens a little when you understand that you are a continuation of something very long. 149:43 Speaker A That the past is not behind you, sealed off and inaccessible. It is in you. It came with you. It is part of the physical structure of who you are. The person who pressed their hand against the stone wall of that cave 32,000 years 149:57 Speaker A ago was in the biological sense we have been tracking our relative. distant. Yes. Separated by time spans that dwarf everything we normally think of as history, but connected through the actual physical mechanism of genetic inheritance through the deoxy 150:13 Speaker A ribboucleic acid that copies itself imperfectly across generations and in doing so creates both the variation that drives evolution and the continuity that keeps populations recognizable across millennia. 150:27 Speaker A That person's blood was not so different from ours. The world they lived in was almost unimaginably different. The inner life they carried, the fears and attachments and curiosities and moments of unexpected delight was, I suspect, not different at all. They wanted to 150:43 Speaker A leave a mark. They wanted something of themselves to remain. And it did. Not just in the ochre outline on the limestone wall preserved by the darkness and the still air of a sealed cave for 32,000 years, but in the blood of the 150:58 Speaker A people who descended from them. In the genes that have been traveling invisibly through the centuries since the cave was sealed. In the bodies of people who have no idea they're carrying something so old. And in the curiosity of people who 151:12 Speaker A do know and who are trying as carefully and rigorously as they can to understand what it means. That is what this story has been at its heart and attempt to understand what the blood remembers. Not to mystify it, not to overclaim, not to 151:26 Speaker A reduce it to something simple when it is not simple, but to sit with the actual evidence, the bones and the genomes and the parish records and the oral traditions and the genealogical databases and the peer-reviewed papers and the cave walls and to ask as clearly 151:42 Speaker A as possible, what is here? What does it mean? And what does it say about who we are and how long we have been on the way to becoming it? The answer, as I hope the past several hours have made clear, 151:53 Speaker A is not a clean one. It is a work in progress. Like all the best answers, the ancient genomics will continue to be refined. New specimens will be found and analyzed. The imunological research will produce clearer results or more 152:07 Speaker A complicated ones or both. The population models will be updated. And at some point, maybe soon, maybe in a generation, someone will be able to answer the questions that are still open with a precision and a confidence that is not yet available. I look forward to 152:23 Speaker A that in whatever form it takes. But for now, for tonight, which is after all the time we are in, the answer is this. You are connected to something very old. 152:33 Speaker A Older than any story you have ever been told about yourself. Older than the oldest nation or the oldest religion or the oldest language, older than agriculture, old enough to have watched the glaciers recede and the forest return and the first seeds go 152:48 Speaker A deliberately into the first turn soil. Whatever is in your blood, it came from somewhere real. And it traveled a very long way to reach you. That is worth knowing. It is worth on a quiet night like this one, taking a moment to feel, 153:03 Speaker A sleep well, carry it lightly, and know that the story, all of it, the whole vast and complicated and still unfinished story of what we are and where we came from is still going. Thank you for spending this time with me 153:14 Speaker A tonight. If this kind of storytelling speaks to you, if you like sitting with history and science and the truly uncertain edges of what we know, then I hope you will stay close. There are more stories waiting. Quieter ones, stranger 153:28 Speaker A ones, ones that begin in places you would not expect and end somewhere you did not see coming. The next one is already taking shape. Until then, rest well. The blood remembers and so I hope will Topics: Rh-negative blood human genetics blood types evolutionary biology natural selection Basque people erythroblastosis fetalis ancient DNA human origins genetic mutation --- This is the markdown twin of https://sozai.app/transcript/rh-negative-blood-ancient-secret/ — the same content, without the markup. Published by SozAI (https://sozai.app). Reuse and quotation are allowed with attribution and a link back. Machine-readable index: https://sozai.app/llms.txt · data API: https://sozai.app/api/