Food Sharing: The Final Frontier
Ellen Furlong

For years the frontier between human and non-human primates has been seen as “civilization” (Peterson & Goodall, 1993). Humans have been viewed as more civilized than other species for many reasons, not least among those our ability to share resources. However, it has been shown many times that some of these animals do share, and in fact they do so very well. Food sharing falls under a broad category called reciprocal altruism which can be defined as “..behavior which is likely to increase the reproductive output of another member of the same species who is not a descendant of the actor, and which at least in the short term is likely also to reduce the number of the actor’s own descendants.” (Bertram, 1982). This definition, while satisfactorily defining a good part of reciprocal altruism, is still somewhat lacking. Another important aspect of reciprocity involves the return of the favor in some shape or form (de Waal, 1996).

This definition certainly holds true for food sharing; if one animal shares with an unrelated hungry individual, one does not help ones genes any. This may seem like a fairly improbable occurrence in the wild; and in fact most monkeys have no concept at all of food sharing (de Waal, 1996). If you give a rhesus macaque a grape he will immediately threaten you. However, chimpanzees and capuchins seem to differ from other animals in this respect; it is a part of the nature of these animals to share (de Waal, 2000, 1996).

Capuchins have been shown to share their food with others of their own species (de Waal, 1996) and have further been shown to discriminate as to with whom they will share (de Waal, 2001). They additionally are able to keep these things in mind; they seem to be able to know “you shared with me so I will share with you” (de Waal, 2001). However, when Capuchins share, they do not actively hand apple pieces to their partners; they simply move close to their partners and allow them to take pieces that fall while they are eating (de Waal, 2001). They share passively, not the active form of sharing, which can be seen in humans.

Chimpanzees have also been shown to share food, in much the same way as the capuchins; usually passive sharing can be observed much more than active giving in chimps as well (de Waal, 1996). Chimps, however, rely on a more complex form of reciprocity than capuchins; seeming to operate on a more sophisticated level (more along the lines of “what have you done for me recently?”) (de Waal, 2001). Chimpanzees seem to cancel the hierarchy during these times (de Waal, 1996); therefore, it seems logical to assume that the behavior of chimps during feeding times would be on average more positive than in the absence of food.

It would also seem logical to take this a step further and conclude that chimps would share equally with all individuals regardless of age or sex; however, according to Hemerlrijk (1990), chimpanzee behavior is different for male-female interactions than it is for female-male interactions, depending on who initiated the contact. Males seem to share more freely and more permissively than females who are choosier when it comes to sharing (de Waal, 2001).

Male chimpanzees often form close coalitions to gain status; it follows that since males form such strong bonds they would possibly share more with other males in their group, and possibly sharing may even help them gain the status they are seeking in their community (de Waal, 1998). Perhaps their interactions would differ during feeding times as compared to during times when no food is present.

Chimpanzee females prove to be interesting cases as well; having even been seen teaching their offspring to use tools to feed. The females leave the tools (rocks, sticks etc) with some nuts in a conspicuous place for the juveniles to practice breaking open (Boesch- Achermann & Boesch, 1993, Fernandez-Carriba & Loeches, 2001). This implies that perhaps adult females would be more permissive with the juveniles, having more positive interactions with them during feeding time than otherwise. Female-Female interactions are interesting cases as well. Females seem to spend a lot of time grooming each other, which is surprising since they are so solitary (Sugiyama, 1988). Perhaps they are more permissive around each other during feeding times as well.

So the question still remains, if you take a chimp to dinner, will he share the dinner rolls?

References

1. Bertram. (1982). Current Problems in Sociobiology. Cambridge University Press. New York, New York. (251-269).
2. Boesch-Achermann, H. & Boesche, C. (1993). Tool use in wild chimpanzees: New light from dark forests. Current Directions in Psychological Science. (18-21).
3. De Waal, F. (1996). Good Natured: The Origins of Right and Wrong in Humans and Other Animals. Harvard University Press. Cambridge, Massachusetts.
4. De Waal, F. (1998). Chimpanzee Politics. Revised Edition. The Johns Hopkins University Press. Baltimore, Maryland.
5. De Waal, F. (2001, April). The Rewards of Cooperation. Symposium conducted at the University of Louisville, Louisville KY.
6. Fernandez-Carriba, S., & Loeches, A. (2001). Fruit smearing by captive chimpanzees: A newly observed food-processing behavior. Current Anthropology, 42. 143-147.
7. Hemerlrijk, K. (1990). Models of, and tests for, reciprocity, unidirectionality and other social interaction patterns at a group level. Animal Behaviour, 39. 1013-1029
8. Peterson, D. & Goodall, J. (1993). Visions of Caliban on Chimpanzees and People. The University of Georgia Press. Athens, Georgia.
9. Sugiyama, Y. (1988). Grooming interactions among adult chimpanzees at Bossou, Guinea, with special reference to social structure. International Journal of Primatology, 9. 393-407.