Chimpanzees share forbidden fruit

Abstract

The sharing of wild plant foods is infrequent in chimpanzees, but in chimpanzee communities that engage in hunting, meat is frequently used as a 'social tool' for nurturing alliances and social bonds. Here we report the only recorded example of regular sharing of plant foods by unrelated, non-provisioned wild chimpanzees, and the contexts in which these sharing behaviours occur. From direct observations, adult chimpanzees at Bossou (Republic of Guinea, West Africa) very rarely transferred wild plant foods. In contrast, they shared cultivated plant foods much more frequently (58 out of 59 food sharing events). Sharing primarily consists of adult males allowing reproductively cycling females to take food that they possess. We propose that hypotheses focussing on 'food-for-sex and -grooming' and 'showing-off' strategies plausibly account for observed sharing behaviours. A changing human-dominated landscape presents chimpanzees with fresh challenges, and our observations suggest that crop-raiding provides adult male chimpanzees at Bossou with highly desirable food commodities that may be traded for other currencies.

Figure 1. An adult male chimpanzee obtains cultivated papaya fruit.

Figure 2. Age/sex classes of crop-sharing dyads.

Offspring are of any age, ‘male’ or ‘female’ always refers to adults, and ‘immature’ refers to infants or juveniles less than 8-years old. Mother-offspring (includes offspring-mother) and male-immature sharing may be explained on the basis of kin selection.