To prove that cooking actually does save energy, Wrangham partnered with Stephen Secor, a University of Alabama biologist who studies the evolutionary design of the digestive system. They found that the python—an animal model with easily studied gut responses—expends less effort breaking down cooked food than raw. Heat alters the physical structure of proteins and starches, thereby making enzymatic breakdown easier.
Wrangham’s theory would fit together nicely if not for that pesky problem of controlled fire. Wrangham points to some data of early fires that may indicate that H. erectus did indeed tame fire. At Koobi Fora in Kenya, anthropologist Ralph Rowlett of the University of Missouri–Columbia has found evidence of scorched earth from 1.6 million years ago that contains a mixture of burned wood types, indicating purposely made fire and no signs of roots having burned underground (a tree struck by lightning would show only one wood type and burned roots). The discoveries are consistent with human-controlled fire. Rowlett plans next to study the starch granules found in the area to see if food could have been cooked there.
Still, most researchers state that unless evidence of controlled fire can be regularly confirmed at most H. erectus sites, they will remain skeptical of Wrangham’s theory. Moreover, other food-based theories can explain the body and brain expansion without flames. One is the expensive tissue hypothesis, proposed in 1995 by Leslie C. Aiello, professor emeritus of biological anthropology at University College London, and physiologist Peter Wheeler of Liverpool John Moores University in England. The main idea of the hypothesis—that smaller guts correlate with bigger brains in primates—fits with Wrangham’s theory, but Aiello and Wheeler think that energy-dense animal-derived foods, such as soft bone marrow and brain matter, were the reason humans developed these characteristics, not cooking.
Lacking the proof for widespread fire use by H. erectus, Wrangham hopes that DNA data may one day help his cause. “It would be very interesting to compare the human and Homo erectus genetics data to see when certain characteristics arose, such as, When did humans evolve improved defenses against Maillard reaction products?” he says, referring to the chemical products of cooking certain foods that can lead to carcinogens.
Even without such evidence yet, some think Wrangham’s theory is just the thing to shake up the field of human evolution.
“It doesn’t matter who develops these ideas,” says Aiello, who is also president of the Wenner-Gren Foundation, which supports anthropological research. “You have to listen to what Richard is saying because he has some very interesting, original data. Sometimes the most creative ideas come from unexpected places.” She points to Goodall, who surprised the world by proving that humans were not the only toolmakers. “It’s one of the best illustrations I know of the value of primate research informing our knowledge of human evolution and adaptation,” Aiello says.
If Wrangham’s strange ideas turn out to be true, we can thank an early hominid Emeril Lagasse who picked a charred tuber out of a campfire and swallowed it. Without that person, we might never have been able to examine our origins—or enjoy a good grilled steak—in the first place.
This article was originally published with the title Cooking Up Bigger Brains.