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  • 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 have 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 us, that's 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 proofthat 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.


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B1 US homo human brain allowed eating gorilla

Why Do We Cook?

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    陳震寰 posted on 2016/04/15
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