Chimpanzees have the cognitive ability to cook, according to new research, if only someone would give them ovens.
It’s not that the animals are ready to go head-to-head with Gordon Ramsay, but scientists from Harvard and Yale found that chimps have the patience and foresight to resist eating raw food and to place it in a device meant to appear, at least to the chimps, to cook it.
That is no small achievement. In a line that could easily apply to human beings, the researchers write, “Many primate species, including chimpanzees, have difficulty giving up food already in their possession and show limitations in their self-control when faced with food.”
But they found that chimps would give up a raw slice of sweet potato in the hand for the prospect of a cooked slice of sweet potato a bit later. That kind of foresight and self-control is something any cook who has eaten too much raw cookie dough can admire.
The research grew out of the idea that cooking itself may have driven changes in human evolution, a hypothesis put forth by Richard Wrangham, an anthropologist at Harvard and several colleagues about 15 years ago in an article in Current Anthropology, and more recently in his book, “Catching Fire: How Cooking Made Us Human.”
He argued that cooking may have begun something like two million years ago, even though hard evidence only dates back about one million years. For that to be true, some early ancestors, perhaps not much more advanced than chimps, had to grasp the whole concept of transforming the raw into the cooked.
Felix Warneken at Harvard and Alexandra G. Rosati, who is about to move from Yale to Harvard, both of whom study cognition, wanted to see if chimpanzees, which often serve as stand-ins for human ancestors, had the cognitive foundation that would prepare them to cook.
One obvious difficulty in creating an experiment was that chimps have not yet figured out how to use fire, and the scientists were wary of giving them access to real cooking devices. So the scientists hit on a method that, as they write in Proceedings of the Royal Society B, presents the chimps with “problems that emulate cooking.”
“We invented this magic cooking device,” Dr. Warneken explained in an interview: two plastic bowls that fit closely together with pre-cooked food hidden in the bottom tub.
When a chimpanzee placed a raw sweet potato slice into the device, a researcher shook it, then lifted the top tub out to offer the chimp an identical cooked slice of sweet potato.
It was known that chimps prefer cooked food, but it was an open question whether chimps had the patience to wait through the pretend “shake and bake” process. And, the researchers wanted to know if the animals could understand “that when something raw goes in there it comes out cooked,” said Dr. Warneken.
He and Dr. Rosati, who contributed equally to the research, spent parts of two years at the Tchimpounga Chimpanzee Rehabilitation Center, a sanctuary in the Republic of Congo and ran nine different experiments, judging different cognitive capacities. The two researchers are married to each other.
The chimps showed a number of indications that, given a real cooking opportunity, they had the ability to take advantage of it. They resisted eating raw food and put it in the device, waiting for cooked food. They would bring raw food from one side of a cage to the other in order to put it in the device. And they put different kinds of food in the device.
Dr. Rosati said the experiments showed not only that chimps had the patience for cooking, but that they had the “minimal causal understanding they would need” to make the leap to cooking.
Other scientists praised the research, but the world of research on chimpanzee cognition is a small one, and many of the scientists know each other and have worked together. Brian Hare at Duke University was not involved in the research, but has worked with Dr. Warneken and was Dr. Rosati’s Ph.D. adviser. Dr. Wrangham was his Ph.D. adviser.
He said in an email, “In 1999, when Wrangham proposed the cooking hypothesis, it seemed silly to some to think that the use of fire was the major impetus to convert upright chimpanzee-like creatures into the first species of humans, but this paper makes that scenario the leading hypothesis in my mind.”
Dr. Laurie Santos at Yale was not involved in this project, but was Dr. Rosati’s postdoctoral adviser. She said it was hard to know what chimps understood about the transition from raw to cooked food, but said similar questions could be asked about “most teenagers who are microwaving their pot pies,” she said.
Whether or not chimpanzees could operate a real oven on their own — Dr. Rosati thinks they probably could — the research leaves no doubt that they have the cognitive ability to take advantage of a restaurant (bring your own potato, of course).