This sounds plausible enough, right?
Humans became human, as it were, with the emergence 1.8m years ago of a species called Homo erectus. This had a skeleton much like modern man’s—a big, brain-filled skull and a narrow pelvis and rib cage, which imply a small abdomen and thus a small gut. Hitherto, the explanation for this shift from the smaller skulls and wider pelvises of man’s apelike ancestors has been a shift from a vegetable-based diet to a meat-based one. Meat has more calories than plant matter, the theory went. A smaller gut could therefore support a larger brain.
So far, so good? Well, via a commenter on Art's private blog who called attention to this article in The Economist, maybe not. What's Cooking? – The evolutionary role of cookery. And, so…
Dr Wrangham disagrees. When you do the sums, he argues, raw meat is still insufficient to bridge the gap. He points out that even modern “raw foodists”, members of a town-dwelling, back-to-nature social movement, struggle to maintain their weight—and they have access to animals and plants that have been bred for the table. Pre-agricultural man confined to raw food would have starved.
Start cooking, however, and things change radically. Cooking alters food in three important ways. It breaks starch molecules into more digestible fragments. It “denatures” protein molecules, so that their amino-acid chains unfold and digestive enzymes can attack them more easily. And heat physically softens food. That makes it easier to digest, so even though the stuff is no more calorific, the body uses fewer calories dealing with it.
In support of his thesis, Dr Wrangham, who is an anthropologist, has ransacked other fields and come up with an impressive array of material. Cooking increases the share of food digested in the stomach and small intestine, where it can be absorbed, from 50% to 95% according to work done on people fitted for medical reasons with collection bags at the ends of their small intestines.
Wow, not such good news for the vegan raw foodists. Not only is the diet designed for large, fermenting guts (and tiny brains), which is bad enough, but now they must also contend with the likelihood that they're getting from 5-50% less nutrition from what they eat than if it were cooked. Then take away the high nutrition of meat and animal fat and it's a recipe for a long-term disaster; and I just don't see how anyone could conclude otherwise. This is why a Palo-like diet with plenty of all such nutritious food (cooked, normally) is super nutritious.
And, there's yet another twist to the story.
Another telling experiment, conducted on rats, did not rely on cooking. Rather the experimenters ground up food pellets and then recompacted them to make them softer. Rats fed on the softer pellets weighed 30% more after 26 weeks than those fed the same weight of standard pellets. The difference was because of the lower cost of digestion. Indeed, Dr Wrangham suspects the main cause of the modern epidemic of obesity is not overeating (which the evidence suggests—in America, at least—is a myth) but the rise of processed foods.
Gratifying to see someone thinking independently, rather than the same old saw that you eat to much and don't exercise enough. The one bugaboo, however, would be the advent of fire. In the article, Dr. Wrangham concedes that the evidence is not conclusive, and thus, there are those all over the map, from 200,000 years all the way back to the advent of Homo erectus 1.8 million years ago.
But it's an interesting hypothesis, that's it's not the meat that evolved us as it did, but the ability to cook; meaning, that our existence is potentially the effect of a technological innovation 1.8 million years ago rather than merely "dumb" stumbling upon or scavenging new food sources.