The raw and the cooked

Which foods are we meant to eat?

By Caroline Cummins

January 12, 2007

A few years ago, Harvard Magazine ran a cover story titled “The Way We Eat Now,” documenting not just our modern eating habits but, evolutionarily speaking, the way we used to eat.

“Compared with other primates, we are evolved to eat foods of high caloric density — meats, roots, seeds,” anthropologist Richard Wrangham told the magazine. Cooking your food, the magazine pointed out, means less work eating — less time and effort spent gnawing, chomping, and swallowing.

Chimpanzees spend about six hours a day downing “a great big pile of leaves, seeds, and roots,” and are rewarded with about 300 or 400 calories per hour of effort. Humans, by contrast, are much more efficient eaters; if we shovel in “cooked, softened food of high caloric density,” we can consume 2,000 calories (a day’s worth of calories) in a mere hour.

An evolutionary side effect of eating cooked instead of raw food is altered skull structure. Chewing is a major workout; the more you chew, the bigger your jaw. (Doubt it? Take a look at any fellow primate behind bars at the zoo.) It’s one reason why we still have wisdom teeth that don’t fit inside our jaws anymore.

So we’re supposed to eat cooked food, right? Well, maybe. In a recent stunt, nine volunteers camped out next to the ape house at a British zoo and spent 12 days on the “Evo Diet,” eating little more than raw fruits and vegetables. (The BBC recently began airing a related TV show, “The Truth About Food.”)

“With so much food bulk and plenty of calories, the subjects did not go hungry,” reported the BBC. “Indeed, most failed to finish their daily ration.” A TV crew filmed the volunteers, hoping that withdrawal from caffeine, sugar, and fat would inspire drama-worthy bickering. Instead, the volunteers lost weight, lowered their blood pressure and cholesterol levels, and decided that fruit and veg were, well, kind of tasty. The downside? Excessive flatulence.

Still, humans aren’t monkeys. “(Among humans), raw-food eating is never practiced systematically anywhere in the world,” Wrangham said, citing a study of German raw-foodists in which 25 percent were chronically underweight and half the women no longer menstruated. A diet that hinders our ability to reproduce is not, evolutionarily speaking, a success.

Humans, after all, aren’t just carnivores or herbivores or rawfoodivores or, in Wrangham’s term, “cookivores.” We’re omnivores. Some of us are less omni than others, but there’s a reason why we’re always told to “eat a balanced diet” –— it keeps us balanced, too.