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They're not likely to start barbecuing in the rainforest, but chimpanzees can understand the concept of cooking and are willing to postpone eating raw food, scientists reported on Tuesday. The findings, based on nine experiments conducted at the Tchimpounga Sanctuary in Republic of Congo and published in Proceedings of the Royal Society B, suggest that chimps have all the brainpower needed to cook, including planning, causal understanding, and ability to postpone gratification. They do lack the ability to produce fire. But if they were given a source of heat, chimps "might be quite able to manipulate (it) to cook," said developmental psychologist Felix Warneken of Harvard University, who conducted the study with Alexandra Rosati.
While the finding may seem esoteric, it lends support to the idea that cooking accelerated human evolution. Cooked food is easier to digest, spurring the growth of large brains in our australopithecine ancestors, Harvard's Richard Wrangham proposed about a decade ago. If chimps have the cognitive skills to cook, australopithecines likely did, too, said Wrangham, who was not involved in the study: "It suggests that with a little extra brainpower, australopithecines could indeed have found a way to use fire to cook food." Archaeological evidence suggests humans began using fire 1 million years ago.
Some of the researchers' experiments confirmed studies by other scientists, such as that chimps prefer seared sweet potatoes to raw. But those studies did not test whether chimps have the mental chops to cook. Other tests did. For instance, the scientists presented chimps with two containers. One yielded cooked food through a false bottom, not actually cooking, and one did not. The chimps learned that one transforms potatoes from raw to cooked. Given a choice of which device to put food in, they almost always opted for the "cooker," showing they understood and willingly waited for the raw-to-cooked transformation.
Chimps did not put pieces of wood that scientists gave them into the cooker, suggesting they grasped that only food can be cooked. Surprisingly, since chimps usually eat food immediately, they were often willing to walk across a room to cook. When the first one did this, the scientists wondered if they had a single "chimpanzee genius," Warneken said. But others showed the same ability, understanding the idea of cooking and postponing gratification to do it.
"We found that chimpanzees prefer cooked food; understand the transformation that occurs during the cooking process; exhibit high levels of self-control to acquire and produce cooked food; and even plan for future opportunities to cook," the researchers said.
There was no evidence, however, that the chimps understood the concept of tipping.