Food For Thought: Meat-Based Diet Made Us Smarter

Comparison of chimpanzee, A. afarensis and human denition.

hide captionOm Nom Nom: As we began to shy away from eating primarily fruit, leaves and nuts and began eating meat, our brains grew. We developed the capacity to use tools, so our need for large, sharp teeth and big grinders waned. From left, a cast of teeth from a chimpanzee, Australopithecus afarensis and a modern human.

William Kimbel/Institute of Human Origins




Until, that is, we discovered meat.





Carving Up The Diet


"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. "What allows us to do what a cat or dog can do are tools."

Tools meant we didn't need big sharp teeth like other predators. Tools even made vegetable matter easier to deal with. 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."

Our teeth, jaws and mouth changed as well as our gut.

A T-bone steak during a food-tasting event in Seoul. i i

hide captionMeat is packed with lots of calories and fat.

Jung Yeon-Je/AFP/Getty Images

Meat is packed with lots of calories and fat.

Jung Yeon-Je/AFP/Getty Images

A Tough Bite To Swallow

But adding raw meat to our diet doesn't tell the whole food story, according to anthropologist Richard Wrangham. Wrangham invited me to his apartment at Harvard University to explain what he believes is the real secret to being human. All I had to do was bring the groceries, which meant a steak — which I thought could fill in for wildebeest or antelope — and a turnip, a mango, some peanuts and potatoes.

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. And half the women in the experiment stopped menstruating.


Wrangham urges me to try some raw turnip. Not too bad, but hardly enough to get the juices flowing. "They've got a tremendous amount of caloric energy in them," he says. "The problem is that it's in the form of starch, which unless you cook it, does not give you very much."

Then there's all the chewing that raw food requires. Chimps, for example, sometimes chew for six hours a day. That actually consumes a lot of energy.

"Plato said if we were regular animals, you know, we wouldn't have time to write poetry," Wrangham jokes. "You know, he was right."

Interactive: Building A Human Body

Much of the body we have today took shape millions of years before the first primate emerged.

Tartare No More

One solution might have been to pound food, especially meat — like the steak I brought. "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 cooking is what he thinks really changed our modern body. Someone discovered fire — no one knows exactly when — and then someone got around to putting steak and veggies on the barbeque. And people said, "Hey, let's do that again."

Besides better taste, cooked food had other benefits — cooking killed some pathogens on food.

But cooking also altered the meat itself. It breaks up the long protein chains, and that makes them easier for stomach enzymes to digest. "The second thing is very clear," Wrangham adds, "and that is the muscle, which is made of protein, is wrapped up like a sausage in a skin, and the skin is collagen, connective tissue. And that collagen is very hard to digest. But if you heat it, it turns to jelly."

As for starchy foods like turnips, cooking gelatinizes the tough starch granules and makes them easier to digest too. Even just softening food — which cooking does — makes it more digestible. In the end, you get more energy out of the food.

Yes, cooking can damage some good things in raw food, like vitamins. But Wrangham argues that what's gained by cooking far outweighs the losses.

As I cut into my steak (Wrangham is a vegetarian; 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; it brings families and communities together at the end of the day and encourages conversation and story-telling — all very human activities.

"Ultimately, of course, what makes us intellectually human is our brain," he says. "And I think that comes from having the highest quality of food in the animal kingdom, and that's because we cook."

So, as the Neanderthals liked to say around the campfire: bon appetit.




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