Speaker A
You wake up at 3:00 a.m. some nights, and you just can't fall back asleep. You blame your phone, stress, or that coffee you had too late. Maybe you're a night owl instead. You feel tired all evening, and then your brain suddenly switches on after midnight. Or maybe you sleep like a rock, but one small noise in the dark still has you wide awake in a second. Most of us never think twice about any of this. But the person wide awake at 3:00 a.m. may have been the most important person in the camp for most of human history. Our ancestors had no walls and no doors. They had a fire burning low and a group of people asleep around it. They slept out in the open in Africa, where lions and leopards do most of their hunting after dark. So somebody had to hear them coming, or the whole camp was dead. But nobody can stay awake every single night. Everyone has to sleep at some point. So, who was listening while the others slept? The answer might explain why your brain switches on after midnight. Let's find out what ancient humans actually did all night. We have to start with something you probably haven't looked at in weeks. The moon. Today, we have street lights, locked doors, and phones that light up the whole room. Their nights had none of that. It got dark for about 12 hours every night near the equator, where our species spent most of its history. The fire and the moon were the only light. So, the moon was a big deal, and some nights it didn't show up at all. The Hadza of Tanzania still live through nights like that. They are one of the last groups on Earth who still live by hunting and gathering. They aren't Stone Age people. They live today, but their nights are the closest look scientists have at life without electricity. The Hadza hold their most important ritual on the darkest nights of the month, when there's no moon at all. It's a dance called the eime. The women sing, and the men take turns, one at a time. Each man puts on a headdress of feathers, ties bells to his ankles, and stomps in time to the song. The Hadza say the ancestors come out of the bush on these nights to dance with them. That sounds like the worst night to be out making noise, because the dark is exactly when predators hunt people. Lion researcher Craig Packer studied nearly 500 lion attacks on people in Tanzania between 1988 and 2009. More than two-thirds of those people died. His team checked the date of every attack. The attacks peaked in the days just after a full moon. Most of them happened between sunset and 10 at night. The moon rises early in the days before a full moon, so the evenings are bright. Lions have a hard time hunting in that light. Things flip after the full moon. The moon rises a little later every night, and the first few hours after sunset stay completely dark. People are still awake and moving around in those hours. Lions come out hungry at the exact moment people are easiest to catch. Packer's data comes from modern Tanzania, but lions and humans shared African nights for hundreds of thousands of years. Our ancestors most likely learned the same pattern. The moon worked like a warning calendar for them. It told them which nights to stay close to the fire. So why would the Hadza dance on the darkest nights of all? Nobody knows for sure, but a whole camp that's awake, singing, and stomping is a lot harder for a predator to sneak up on. That dance also breaks one of the biggest myths about ancient humans. Most people imagine there was nothing to do in the dark, so everyone just lay down and went to sleep when the sun went down. But that's not what scientists see. A team led by Gandhi Yetish and Jerome Siegel tracked the sleep of three groups who still live without electricity. They studied the Hadza in Tanzania, the San in Namibia, and the Tsimane in Bolivia. They published the results in 2015. These people stayed awake for more than three hours after sunset on average. Our video on what ancient humans did all day showed what filled some of those hours. The fire was where the stories came out. Most people spent those evening hours right there around the fire, talking. But fire did one more thing for them. It let people carry light with them. Some of the clearest proof comes from caves in Ice Age Europe, tens of thousands of years ago. There's no light at all deep inside a cave. Day or night, people still walked in there again and again, carrying fire in their hands. So, how long do you think that light lasted? A team of archaeologists in Spain rebuilt Stone Age lights in 2021 and tested them inside a real cave called Ysuna. A torch made of sticks and tree resin burned for about 41 minutes on average. A stone lamp burning animal fat lasted over an hour, but it only lit up a few meters around you. And a small fire on the cave floor made so much smoke that it went out after about half an hour. Now, picture it. You're deep inside a cave with a torch in your hand. The way out is far behind you, and that torch has about 40 minutes left before it burns out. People took that risk to paint the walls. Chauvet Cave in France has paintings more than 30,000 years old, and one of them is a bison with eight legs. That just looks like a mistake in daylight. But archaeologist Mark Azéma studied these paintings the way people back then would have seen them, by the light of a flickering flame. The extra legs seem to run as the flame moves. Azéma thinks some artists made animals move on purpose, a bit like a flip book. That would mean people were watching the first cartoons by firelight more than 30,000 years ago. And it wasn't only adults in there. Small fingers pressed lines and swirls into the soft walls of Rouffignac Cave, also in France, about 13,000 years ago. Researchers Jess Cooney and Leslie Van Gelder measured those finger marks against modern children's hands. A few were made by kids as young as three. And some of those marks are high up on the ceiling, where no three-year-old could ever reach. So, somebody, maybe a mom or a dad, lifted that child up in the dark, held them there by the light of a flame, and let them draw. The moon may have ended up on those walls, too. Ben Bacon is a furniture restorer from London, not a professional scientist. He studied hundreds of cave paintings using the British Library and the internet, and he noticed rows of dots painted next to the animals. He published a study with a team of archaeologists in 2023. His idea is that each dot counts one moon starting from spring, and the number of dots matches the month that animal mated. That would mean people were keeping a calendar on cave walls more than 20,000 years ago. Not every archaeologist agrees, but a furniture restorer might have cracked a code that sat in the dark for 20,000 years. The torches burn out eventually, and everyone has to lie down somewhere. And we still haven't found the person who stayed awake while the rest of the camp slept. We'll get there. First, let's see where they slept. Ancient people didn't sleep deep inside caves. That's another myth. People lived at cave entrances, under rock overhangs, and out in the open. The deep, dark parts of caves were places you visited with a torch, not places you lived. And they weren't sleeping on bare dirt, either. Archaeologist Lyn Wadley and her team found the remains of grass beds at Border Cave in South Africa, about 200,000 years old. That's more than 120,000 years older than any beds found before. And these beds had a clever trick. A layer of ash sat under the grass. Ash makes it hard for crawling insects to move through, so it may have kept bugs out of the bed. The team even found burned leaves of camphor in the bedding. Camphor is a plant people still use today to keep insects away. That means people had a mattress and bug spray 200,000 years ago, before they had anything we'd call a house. But the bugs found a way in anyway. Scientists at Virginia Tech studied the DNA of bed bugs and found that they used to live on bats in caves. One grou
