Primate sociality in evolutionary context

Abstract

Much work has been done to further our understanding of the mechanisms that underlie the diversity of primate social organizations, but none has addressed the limits to that diversity or the question of what causes species to either form or not form social networks. The fact that all living primates typically live in social networks makes it highly likely that the last common ancestor of living primates already lived in social networks, and that sociality formed an integral part of the adaptive nature of primate origins. A characterization of primate sociality within the wider mammalian context is therefore essential to further our understanding of the adaptive nature of primate origins. Here we determine correlates of sociality and nonsociality in rodents as a model to infer causes of sociality in primates. We found sociality to be most strongly associated with large-bodied arboreal species that include a significant portion of fruit in their diet. Fruits and other plant products, such as flowers, seeds, and young leaves, are patchily distributed in time and space and are therefore difficult to find. These food resources are, however, predictable and dependable when their location is known. Hence, membership in a social unit can maximize food exploitation if information on feeding sites is shared. Whether sociality evolved in the primate stem lineage or whether it was already present earlier in the evolution of Euarchontoglires remains uncertain, although tentative evidence points to the former scenario. In either case, frugivory is likely to have played an important role in maintaining the presence of a social lifestyle throughout primate evolution.

Evolution of angiosperm seed disperser mutualisms: the timing of origins and their consequences for coevolutionary interactions between angiosperms and frugivores

“…Animals would also have been subjected to consistent directional selection to evolve into specialized frugivores. Suggested adaptations for fruit-eating, for example dentition in Cretaceous mammals (Wilson et al, 2012), trichromatic vision in primates (Dominy et al, 2003), social behaviour in primates (Müller & Soligo, 2005), and various form of bill shapes, e.g. in toucans (Patané et al, 2009), all indicate strong directional selection.…”

Foraging Cognition in Nonhuman Primates

“…Why did primates benefit more than other social animals from increased encephalization? The relationship between neocortex and group size is certainly real, but the causal arrow could also point the other way: Primates have evolved large brains for nonsocial reasons, which enables them to live in larger groups, form more complex social systems, and maintain more complex social relations than other smaller-brained species (Müller & Soligo, 2005).…”

Effects of the Distribution of Female Primates on the Number of Males

“…We focus here on three major questions that have arisen since the publication of Nunn [10]. First, a shift has occurred in the conception of primate sociality [69], [70]. Recognizing the diversity of social systems, grouping patterns are now categorized as cohesive and dispersed based upon the inter-individual distances of social group members.…”