Food For Thought: Meat-Based Diet Made Us Smarter : NPR

Our earliest ancestors ate their food raw — Digestion, she says, was the energy-hog of our primate ancestor's body. "The closest relative of human tapeworms are tapeworms that affect African hyenas and wild dogs," she says. That would have happened if, say, we were scavenging on the same carcass that hyenas were. which uses about 20 times as much energy as the equivalent amount of muscle — piped up and said, "Please, sir, I want some more." Sorry, vegetarians, but eating meat apparently made our ancestors smarter — smart enough to make better tools, which in turn led to other changes, says Aiello. "If you look in your dog's mouth and cat's mouth, and open up your own mouth, our teeth are quite different," she says. As anthropologist Shara Bailey at New York University says, they were like "external" teeth. "Your teeth are really for processing food, of course, but if you do all the food processing out here," she says, gesturing with her hands, "if you are grinding things, then there is less pressure for your teeth to pick up the slack." As we slice up the turnip and put the potatoes in a pot, Wrangham explains that even after we started eating meat, raw food just didn't pack the energy to build the big-brained, small-toothed modern human. He cites research that showed that people on a raw food diet, including meat and oil, lost a lot of weight. Many said they felt better, but also experienced chronic energy deficiency. "They've got a tremendous amount of caloric energy in them," he says. Tartare No More One solution might have been to pound food, especially meat — "If our ancestors had used stones to mash the meat like this," Wrangham says as he demonstrates with a wooden mallet, "then it would have reduced the difficulty they would have had in digesting it." But pounding isn't as good as cooking that steak, says Wrangham. And people said, "Hey, let's do that again." Besides better taste, cooked food had other benefits — cooking killed some pathogens on food. Even just softening food — which cooking does — he settles for the mango and potatoes), Wrangham explains that cooking also led to some of the finer elements of human behavior: it encourages people to share labor; "And I think that comes from having the highest quality of food in the animal kingdom, and that's because we cook."