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After providing the "oven," Rosati and Warneken gave the chimps slices of uncooked white sweet potato. But then you almost could see them have this insight like, Oh, my goodness, I can put it in this device and it comes back cooked," Rosati says. About half the chimps became regular users of the faux oven, Rosati says. And those chimps pretty much ignored a second device that returned their food uncooked. When researchers gave them a cooked potato slice, they simply ate it. But when they got a raw carrot, they immediately put it in the device.
And their preference for cooked food was so strong that they would hold on to raw potatoes, or carry them to other locations, in order to have them cooked. Previously, chimps and their close cousins, bonobos like Kanzi, who is pictured above , have been taught to cook by people.
They may be stronger and faster than us, they may be more violent and aggressive, but no animal can beat our ingenuity in creating weapons to hunt or fight other animals. Annual Review of Anthropology. One female started washing and dipping her potatoes in salty water rather than simply brushing them, apparently found the taste much improved and, soon enough , her mother and then most of the tribe started dipping their potatoes in the ocean to add salt and flavor to them. But when they got a raw carrot, they immediately put it in the device. While this is not a conclusive test on its own, additional tests along these lines will help to uncover what, exactly, the chimpanzees are basing their choices upon and whether there is any recognition of the possibility to transform food via cooking. The belief we can determine rape in animals seems to me to require astonishing hubris. Such approaches, when done with multiple species, and ideally in conjunction with an assessment of developmental data from humans, advance our understanding of the emergence of complicated cognitive and behavioral patterns shown by humans and perhaps hominid ancestors by identifying these constituent capacities.
But this is the first study showing that animals can acquire a cooking-like skill on their own. The results add to a debate about whether early humans had the brain power to figure out cooking, an activity that requires planning, a willingness to delay gratification and sophisticated use of a tool, Rosati says. The new study was inspired by the work of a colleague at Harvard, Richard Wrangham , a professor of biological anthropology.
His book Catching Fire: How Cooking Made Us Human argues that early humans began cooking almost immediately after learning to control fire, something Wrangham believes happened about 2 million years ago. The new study suggests that even back then, our ancestors had brains that were ready to barbecue, Wrangham says. The study also offers a reminder that very few behaviors are uniquely human, Wrangham says. And, such learning does not require an interpretation of any knowledge about why a better food emerged. By way of analogy, consider a microwave.
The experience of seeing frozen foods placed into a microwave become cooked foods does not require any understanding of that cooking process as many parents of young children can attest, and in fact, most adults do not understand exactly how a microwave cooks food. Rather, the thing people realize is that putting lower preference foods into a microwave leads to higher preference foods coming out some time later through the experiences of seeing that happen with repeated use of the microwave.
We know of no claims that the monkeys understand this process, almost certainly acquired when a macaque accidentally washed a potato in the ocean instead of the nearby freshwater stream and liked the results. When given a new food raw carrot , the chimpanzees placed this new food into the cooking pot.
Again, this can be explained by preferences without claiming that chimpanzees were choosing to cook new raw foods. Rather, it seems that the chimpanzees ate things they liked cooked potatoes and got rid of those they did not like raw potato and raw carrot by utilizing the approach that had previous resulted in more preferred foods i. What would have happened had the authors introduced a third container to the chimpanzees that always gave an uncooked, high preference item?
This trading behavior is well-established with chimpanzees in a variety of other self-control tests in which delayed rewards are obtained that are better than immediate ones e. However, it could also be explained by a preference for a known item uncooked potato over an unknown one the wood chip , or a reflection of their preference for the uncooked potato over the wood chip even if they preferred the cooked potato to both.
While this is not a conclusive test on its own, additional tests along these lines will help to uncover what, exactly, the chimpanzees are basing their choices upon and whether there is any recognition of the possibility to transform food via cooking. It was shown that the chimpanzees would wait to trade raw foods and even transport those foods, rather than eat them.
This is a compelling example of self-control, and perhaps anticipatory behavior e. However, our interpretation of these results with regard to cooking knowledge follows from what we outlined above. Chimpanzees learned that not eating low preference foods would allow them to exchange those for higher preference foods, but such learning does not require understanding that a cooking process occurs. Here, additional testing could be conducted to distinguish whether knowledge of cooking is required or not.
One could allow the chimpanzees to put items into the cooking device and also decide how long to cook the food. What if taking it out too early meant that the food was only partly cooked, or if the food was spoiled if cooked for too long? We would suggest that some understanding of temporal aspects of cooking also would be necessary to demonstrate before concluding that chimpanzees understand the process of cooking.
Perhaps the chimpanzees would show these abilities, although they might not readily understand how time correlates with degree of change in cooked foods. But even some sensitivity to the temporal aspects of cooking would support a claim that chimpanzees understand components of the cooking process.
Although we are playing the role of killjoys here Shettleworth, , this does not mean that chimpanzees cannot understand cooking, or that we think that there is not something to be learned about the origins of human cooking from studying chimpanzees and other nonhuman animals. Rather, we argue that the data presented by Warneken and Rosati do not require such an interpretation.
A key control condition that was lacking was to present chimpanzees with the choice of cooking and non-cooking containers when the presented food was a type that would not be improved. For example, if it was shown that chimpanzees do not prefer cooked apples over raw apples, then they should not put apples in the cooking pot. One could present them with a frozen food that melts and disappears when heated.
Or, given that many primates seem to prefer to take hard items such as chow biscuits and soften them in water, would the chimpanzees understand that the cooking pot would make already-soft chow harder, and thus less palatable? If proficient choice of the correct container cooking foods that get better with heat and not cooking foods that get worse did not happen during generalization tests, and required the same degree of learning and experience with the introduction of each new food type as with previous types, then one likely should not argue that they understood the concept of cooking.
A key point is that foods would have to be chosen that were of medium preference in a raw state so that, for those that got better, the chimpanzees would want to cook them, but those that got worse were acceptable to be eaten without cooking. However, showing that chimpanzees prefer cooked to uncooked potato, and will make choices to gain the more preferred option, tells us very little about whether they understand the process of cooking. And, why should they?
Unlike early hominids, chimpanzees lack fire or a diet heavy in foods whose nutritional value or palatability is increased through the act of cooking they eat primarily fruit and leaves , so they lack both a mechanism for cooking and a motivation to develop it. Of course, at some point, so did early humans, and it is debatable whether a conception of cooking is even required initially. It is possible that a preference for cooked food, and the willingness to wait to acquire it, preceded such understanding. Cooking has long been viewed as a pivotal hominid innovation.
However, they suggested that their data shed light on: Their data, unfortunately, contribute only marginally to these questions. Ardipithecus ramidus , the oldest well-known hominid at 4. The point here is that chimpanzees, bonobos and their precursors have been evolving, and apparently substantially so, right along with but separately from our immediate ancestors.
Perhaps these capacities, realized in chimpanzees and hominids in natural circumstances, were only co-opted by hominids when they learned to harness fire toward the new goal of gathering and transforming certain kinds of foods in ways that we now call cooking.
But what if these capacities, in whole or in part, are also present in other primates, or mammals, or vertebrates that are much less closely related to humans? Some of the purported psychological prerequisites for cooking may have been around a long time, perhaps tens of millions of years, something that cannot be recognized without applying a more broadly comparative approach i. Other problems—including some concerning the second question, on the rapidity of hominid behavioral change—arise from a taxonomically-limited focus.
For example, Warneken and Rosati suggested that, in addition to the control of fire, a slight modification in diet and increased social tolerance compared to chimpanzees could lead to regular hominid cooking. This is assuming, again, that the Pan - Homo last common ancestor was highly similar to Pan troglodytes in ecology and social structure. This is a problematic assumption Lovejoy, that in this case potentially mischaracterizes the requirements necessary for a shift to cooking.
Studies from a broader perspective have suggested other crucial characters relevant to hominid behavioral evolution marked unspecialization, neoteny-related curiosity and information-seeking, etc. Given these points, and the fact that no other organisms have controlled fire, it is unclear how likely it should be that chimpanzees would understand the process of cooking, even if they have a suite of capacities that are relevant to an understanding of cooking. Information from chimpanzees, other nonhuman primates, and indeed other nonhuman animals, are vital for helping understand ourselves but, as Rosenbluth and Wiener , p.
All authors contributed to writing this commentary. First, the experimenters presumably had an expectation that the chimpanzees might prefer one container over the other, and yet there were no controls in place to prevent experimenter cuing of the chimpanzees Beran, Second, their inter-temporal choice test made use of pointing to food items as the measured response.
It is difficult for nonhuman primates to inhibit pointing to larger or better amounts of visible food e. Beran, Georgia State University. Hopper, Lincoln Park Zoo. Ken Sayers, Georgia State University. Brosnan, Georgia State University. National Center for Biotechnology Information , U. Author manuscript; available in PMC Jun 1.
Beran , Lydia M. Hopper , Frans B. Author information Copyright and License information Disclaimer. Beran, Georgia State University;. The publisher's final edited version of this article is available at Learn Behav. Chimpanzees, Cooking, Evolution, Hominids, Learning.
Warneken and Rosati — Experiments and Results Through a series of experiments, Warneken and Rosati showed that chimpanzees preferred cooked potatoes over uncooked potatoes Experiment 1 and were willing to trade the less-preferred uncooked potatoes for the more preferred cooked ones Experiments 2 and 3. Preference for cooked foods over uncooked foods and willingness to trade for cooked food It has previously been shown that chimpanzees trade foods in their possession for foods they like better Brosnan et al.
Preferences for the cooking pot over the non-cooking pot and evidence for self-control Warneken and Rosati suggested that the preference for placing foods into the cooking pot suggested that chimpanzees understood that the cooking pot alone would transform uncooked foods into cooked foods.
Can Chimpanzees Understand Cooking? Should Chimpanzees Understand Cooking?
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Chimpanzees Pan troglodytes show self-control through their exchange behavior.
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