Chimpanzees, Pan troglodytes, share food in the same way after collaborative and individual food acquisition

摘要

We investigated the hypothesis that patterns of chimpanzee food sharing are influenced by whether individuals contributed to its acquisition collaboratively. In two experiments we exposed pairs of captive chimpanzees to food acquisition/sharing situations in which we manipulated (1) whether or not the two individuals had worked together collaboratively to retrieve the food and (2) the proximity of the individuals to the food at the moment of retrieval. The first experiment resembled a scramble competition scenario, with nonmonopolizable food. Proximity of individuals to the food when it arrived was the major variable affecting amount obtained by subordinates. Whether or not the food was obtained via collaboration had no effect. The second experiment resembled a contest competition scenario, as the food was a single large piece of fruit that could be more readily monopolized. In this scenario, dominants obtained more food than subordinates, the amount of food obtained by 'noncaptors' was affected by their proximity to the food when it arrived, and again previous collaboration had no effect. These results suggest that in many food acquisition situations first-arriver and first-possessor chimpanzees, as well as dominants in general, have a significant advantage in food acquisition, but being a collaborator brings no extra benefits.