46 research outputs found
Food Sharing across Borders
Evolutionary models consider hunting and food sharing to be milestones that paved the way from primate to human societies. Because fossil evidence is scarce, hominoid primates serve as referential models to assess our common ancestors’ capacity in terms of communal use of resources, food sharing, and other forms of cooperation. Whereas chimpanzees form male-male bonds exhibiting resource-defense polygyny with intolerance and aggression toward nonresidents, bonobos form male-female and female-female bonds resulting in relaxed relations with neighboring groups. Here we report the first known case of meat sharing between members of two bonobo communities, revealing a new dimension of social tolerance in this species. This observation testifies to the behavioral plasticity that exists in the two Pan species and contributes to scenarios concerning the traits of the last common ancestor of Pan and Homo. It also contributes to the discussion of physiological triggers of in-group/out-group behavior and allows reconsideration of the emergence of social norms in prehuman societies
Chimpanzee lip-smacking facilitates cooperative behaviour
Signalling plays an important role in facilitating and maintaining affiliative or cooperative interactions in social animals. Social grooming in primates is an example of an interaction that requires coordination between partners but little is known about communicative behaviours facilitating this activity. In this study, we analysed the communication of wild chimpanzees of Budongo Forest, Uganda, as they entered and maintained a naturally occurring cooperative interaction: social grooming. We found that lip-smacking, a distinct multimodal oral gesture produced during grooming, coordinated this activity. Lip-smacking at the beginning of grooming bouts was significantly more often followed by longer and reciprocated bouts than silent grooming initiations. Lip-smacks were more likely to be produced when the risk of termination of the interaction by the recipient was high, for instance when grooming vulnerable body parts. Groomers were also more likely to produce lip-smacks during face-to-face grooming where the visual aspect of the signal could be perceived. Data are consistent with the hypothesis that chimpanzee lip-smacks function to coordinate and prolong social grooming, suggesting that this oral signal is an example of a communicative behaviour facilitating cooperative behaviour in chimpanzees
The evolution of food sharing in primates
The aim of this study is to explain the occurrence
of food sharing across primates. Defined as the unresisted
transfer of food, evolutionary hypotheses have to explain
why possessors should relinquish food rather than keep it.
While sharing with offspring can be explained by kin
selection, explanations for sharing among unrelated adults
are more controversial. Here we test the hypothesis that
sharing occurs with social partners that have leverage over
food possessors due to the opportunity for partner choice in
other contexts. Thus, we predict that possessors should
relinquish food to potential mates or allies, who could
provide or withhold matings or coalitionary support in the
future. We used phylogenetic analyses based on both
maximum likelihood and Bayesian approaches in a sample
of 68 primate species to test these predictions. The analyses
strongly indicate that (1) sharing with offspring is predicted
by the relative processing difficulty of the diet, as measured by the degree of extractive foraging, but not overall diet
quality, (2) food sharing among adults only evolved in
species already sharing with offspring, regardless of diet,
and (3) male–female sharing co-evolved with the opportunity
for female mate choice and sharing within the sexes
with coalition formation. These results provide comparative
support for the hypothesis that sharing is “traded” for
matings and coalitionary support in the sense that these
services are statistically associated and can thus be selected
for. Based on this, we predict that sharing should occur in
any species with opportunities for partner choice