Freshly cooked meals may not be an option in the wild, but an extensive taste test involving several great apes has revealed that, like humans, they seem to prefer cooked foods over raw.
The finding counters the belief that humans developed a preference for cooked chow well after we began to control fire.
Instead, it's now believed that a preference for cooked foods -- which tend to be softer and sweeter -- existed in our hominid ancestors before controlled fire emerged. Since that happened between one million and 1.6 million years ago, hominids probably began to cook their food not long thereafter, according to the new study, which has been accepted for publication in the Journal of Human Evolution.
"Given our evidence, early hominids would have already had a preference for the taste of cooked foods, so it is more likely that cooking may have emerged soon after the control of fire," lead author Victoria Wobber told Discovery News.
Wobber, a Harvard University anthropologist, with colleagues Brian Hare and Richard Wrangham, conducted multiple food tests using captive chimpanzee, bonobo, gorilla and orangutan populations from facilities in the United States, Europe and the Congo Republic.
In the first test, a group of chimps was offered a choice between raw and cooked carrots, sweet potatoes and white potatoes. The second test offered apes of each kind either cooked or raw cubed, mashed or grated carrots, since carrots came out as a chimp favorite in the first experiment.
For the third test, the apes were offered a choice between cooked or raw apple and cooked or raw beef. Finally, the researchers gave the Congo chimps, which had never eaten cooked food of any kind, a choice between cooked and raw beef.
All of the ape tasters preferred cooked over raw foods, with the exception of white potatoes and apples. In those instances, they demonstrated no preference between cooked or raw, perhaps because these items are easily chewed raw, and cooking them does not enhance their sweetness.
During the second experiment, designed to compare food textures, the apes turned their noses up to raw, grated carrots and showed that they strongly preferred the vegetable cooked and mashed.
"It is likely that the properties present in cooked foods are preferable to most mammals, as rats and cats have both been shown to prefer cooked food or cooked taste," Wobber said, adding that in the wild, chimpanzees will choose fire-toasted seeds over raw ones, a rare instance demonstrating how nature can sometimes act like a chef.
Other studies on great apes show they "tend to select foods based on nutritional content, with some indices of taste, in addition to potential visual or smell cues," she added.
For example, she explained, "wild primates will choose ripe over unripe fruit, potentially sensing that the ripe fruit is softer."
Cooking usually softens food or, at least in the case of meat, makes it easier to chew, and it also can bring out sweetness and umami, the scientists believe. Umami tends to enhance other flavors and is popularly associated with certain Asian foods such as soy sauce.
Peter Lucas, a George Washington University anthropologist, recently conducted a study on foods that two early hominids -- Australopithecus africanus and Paranthropus robustus -- consumed, based on teeth wear and carbon measurements in dental enamel.
Lucas found that these ancient human ancestors must have eaten a lot of hard, brittle foods, but that roasting tubers gradually lessened the work of chewing and, by inference, the cost of digestion. In short, roasted root veggies became the far more appealing option, particularly for later hunter-gatherer groups.
Lucas told Discovery News that the paper by Wobber's team "is intriguing, the experiments are innovative and the results seem very reasonable."
In the future, he hopes a follow-up study might more closely "check what the cooking actually does to change food properties, both chemical and physical" before making firm conclusions about what drives mammalian food preferences.