Nearly 2 million years ago, it seems the original naked chef was cooking up a storm. Homo erectus, the extinct hominid that’s a mere branch or so away from humans on the family tree, was the first to master cooking, new evidence suggests. This seminal event had huge implications for hominid evolution, giving the ancestors of modern humans time and energy for activities such as running, thinking deep thoughts and inventing things like the wheel and beer-can chicken.
“In the big picture, eating cooked food has huge ramifications,” says Harvard’s Chris Organ, a coauthor of the new study. Cooking and other food-processing techniques aren’t just time-savers; they provide a bigger nutritional punch than a raw diet. The new work is further evidence that cooking literally provided food for thought, making it easier for the body to extract calories from the diet that could then be used to grow a nice, big brain.
Humans are the only animals who cook, and compared to our living primate relatives we spend very little time gathering and eating food. We also have smaller jaws and teeth.
Homo erectus also had small teeth relative to others in the human lineage, and the going idea was that hominids must have figured out how to soften up their food by the time that H. erectus evolved. But behavioral traits such as the ability to whip up a puree or barbecue ribs don’t fossilize, so a real rigorous test of the H. erectus-as-chef hypothesis was lacking.
Organ and his colleagues, including Harvard’s Richard Wrangham, an early champion of the cooking hypothesis, decided to quantify the time one would expect humans to spend eating by looking at body size and feeding time in our living primate relatives. After building a family tree of primates, the researchers found that people spend a tenth as much time eating relative to their body size compared with their evolutionary cousins — a mere 4.7 percent of daily activity rather than the expected 48 percent if humans fed like other primates.
Then the team looked at tooth size within the genus Homo. From H. erectus on down to H. sapiens, teeth are much smaller than would be predicted based on what is seen in other primates, the team reports online the week of August 22 in the Proceedings of the National Academy of Sciences.
“Tooth size becomes dramatically smaller than what we would expect,” says paleoanthropologist David Strait of the University at Albany in New York, who was not involved with the work. “This is really compelling indirect evidence the human lineage became adapted to and dependent on cooking their food by the time Homo erectus evolved.”