We have two comments regarding the conclusion that chimpanzees share cultivated fruits because these are riskier to obtain and thus represent a more valuable resource. We question first, whether the chimpanzees perceive these fruits as being risky to obtain, and second, whether they are deliberately sharing these fruits more than other foods.

In terms of chimpanzees perceiving the stolen fruit as “forbidden,” as a group that studies cognition we doubt that chimpanzees possess enough of a notion of possession to understand that they are “stealing” from humans something which they “should” not. The chimpanzees did scratch more when they were in the cultivated areas, suggesting they were stressed, and it was useful that the authors provided this data. Yet we see several reasons why individuals could be stressed other than possessing a concept of theft. They may perceive the situation as dangerous because they have past experience with humans being angry at their invading this area. More simply, they might just be excited by the novelty of being in this new area. We think that it is difficult to differentiate between these possibilities with the data presented, thus we suggest that the authors temper their claim a bit about the risk factor leading to males receiving “positive attention” (since they could even just receive attention because they are holding a coveted food item).

In regard to the issue of deliberate sharing of cultivated fruits, it is possible that individuals share these fruits simply because the stressful situation of obtaining them causes them to lose their appetite or lower their defenses when others try to take the food. Thus, tiredness, rather than any sense of having obtained a valuable resource, might lead to increased sharing. In fact, it might not even be that they are deliberately sharing the cultivated fruits more than other foods because of the situation required to obtain them. Rather, it is possible that these fruits are more shareable simply because they are larger, i.e. a standard cultivated papaya is much larger than a wild fig, thus making it easier to share simply because there are more pieces which might fall off while the individual is eating it. Also, these food resources may be more valuable simply because they are nutritionally better than the standard chimpanzee diet, rather than the “forbidden” element of the fruits adding any value. So again, we suggest considering more simple alternatives before proposing these more complex explanations of what is certainly interesting data.