Richard M. Cook

Transcription

[music] People around the world celebrate many different holidays for many different reasons. But no matter how we celebrate, most of us have one thing in common, and that's sitting down to a big holiday meal together. We're not the only social animals that sit down to eat together, but we are the only ones who cook. Cultural anthropologist Claude Levi-Strass, cooking establishes the difference between animals and people, although I think he'd agree that pants make a big difference too. I think he was probably talking about the cultural attachments to cooking, the ceremonies, or the tools, but he was right in a completely different way. Cooking literally allowed us to become human, in the most basic biological and evolutionary sense of the word. This theory is championed by people like Harvard's Richard Wrangham. He says, above all else, cooking allowed us to transition from primitive ape to complex human. it allowed us to feed our growing brains, and it opened up a lot of free time. The success of human culture and evolution is because of our remarkably advanced brain, it's 100 billion neurons full of language and creativity and curiosity, but that brain comes at a cost. It uses 1/5th of the calories that we eat. I guess with great power, comes great hunger. We've got enormous brains in relation to our body size, and that's one of the key differences between us and our primate cousins. Take gorillas for instance: they're three times as massive as humans, but their brains only have one-third the number of neurons. Scientists actually estimate that for a gorilla to power a brain the size of ours, they'd have to add 700 calories to their daily diet. The thing is gorillas already spend 80% of their daylight hours eating. Their diet is mostly leaves and fruits, and all raw. Chimpanzees, too, spend more than half of their day eating, compared with just 5%, but most of that's probably waiting in line. Gorillas and chimps share more in common with human ancestors like Australopithecus than they do with us. Compared to humans, gorilla skulls have enormous jaws, and huge teeth and powerful ridges to attach chewing muscles, which are all adaptations to a diet that consists mainly of dense, fibrous plant matter. We see a lot of those same traits in Australopithecus, but then something happened around 1.8 million years ago, brains and body sizes doubled, in the form of Homo erectus, the first modern human. While Australopithecus looks distinctly ape-like, if you saw Homo erectus walking down the street, you'd pretty much recognize it as human, except for the lack of pants again. But inside of Homo erectus' basically human skull is a basically human brain, which means that it had figured out a way to get a lot more energy out of its food. Part of that is thanks to hunting and eating large animals, but also to tools that allowed it to cut meat from large animal carcasses and break bones to get at their calorie-rich marrow. While Homo erectus probably ate meat when they could get it, we think they still ate mostly plants, and it's cooking that made the difference. When plants are cooked, it breaks down their tough cell walls, which lets them release more of their nutrients, and it makes them easier to chew. Not only that, heat denatures or unwinds proteins, which allows our bodies to digest them easier and it inactivates plant toxins. This means that our ancestors could have gotten access to more foods, and more energy than ever before. This works with animal and meat products too, you can see it every time you cook an egg, as you go from clear to white. There's a catch, though. Scientists haven't found definitive proof that Homo erectus harnessed fire 1.8 million years ago, but that could be because things like burnt sticks don't fossilize well, and well, fossils from that era are pretty rare to begin with. Cooking can mean a lot more than just putting your food over fire, though. Maybe it means crushing it up into a more edible form, or it could mean preserving it and breaking down with salt, maybe it means cutting it into pieces and drying it up in the sun, or mashing it up into an edible form like this, and maybe you let nature do the work for you. Because our ancestors were spending less time eating, that gave them a bunch of free time to do things like develop language, or invent art, and tools. Chimps mostly eat food where they find it, and they'll gladly take food from another chimp. "I drink your milkshake" But when our ancestors started cooking food, that means they'd bring it back to a central location, and that means they'd have to strengthen social bonds and cooperation. Maybe cooking helped us evolve to just get along. They would have had to invent new tools to carry their food around in, our children would have lived longer, and so would our adults. We ate our way to becoming a stronger species. When you sit down to your next holiday meal and your weird Uncle Larry starts talking about politics again, well, just remember that cooking, together, is a big part of what makes you human, and hey, at least you'll have something else to talk about. Stay curious. If you'd like to know more about the evolution of human cooking, check out Richard Wrangham's "Catching Fire - How Cooking Made Us Human" I've got a link down in the description. And of course, if you'd like to continue to feed your brain, well, subscribe. Special thanks to the Thinkery, Austin's new children's museum, where science and families play side by side. See ya later.