Socioecological complexity in primate groups and its cognitive correlates

Abstract

Characterizing non-human primate social complexity and its cognitive bases has proved challenging. Using principal component analyses, we show that primate social, ecological and reproductive behaviours condense into two components: socioecological complexity (including most social and ecological variables) and reproductive cooperation (comprising mainly a suite of behaviours associated with pairbonded monogamy). We contextualize these results using a meta-analysis of 44 published analyses of primate brain evolution. These studies yield two main consistent results: cognition, sociality and cooperative behaviours are associated with absolute brain volume, neocortex size and neocortex ratio, whereas diet composition and life history are consistently associated with relative brain size. We use a path analysis to evaluate the causal relationships among these variables, demonstrating that social group size is predicted by the neocortex, whereas ecological traits are predicted by the volume of brain structures other than the neocortex. That a range of social and technical behaviours covary, and are correlated with social group size and brain size, suggests that primate cognition has evolved along a continuum resulting in an increasingly flexible, domain-general capacity to solve a range of socioecological challenges culminating in a capacity for, and reliance on, innovation and social information use in the great apes and humans. This article is part of the theme issue ‘Cognition, communication and social bonds in primates’.

A Comparative Perspective on the Cerebello-Cerebral System and Its Link to Cognition

“…In this way, models can be generated that show which combination of proxies for cognitive abilities may drive cerebellar and, more specifically, ansiform area evolution. These drivers may, for instance, come from a combination of social or dietary demands, behavioral innovations, or technical demands stemming from for example tool use, bedding requirement, or brachiation challenges as per the Technical Intelligence hypothesis [131,160,[200][201][202].…”

Structural and Cognitive Solutions to Prevent Group Fragmentation in Group-Living Species

“…I do not use phylogenetic methods because these cannot identify grades when present in data [2,41]. As it happens, in primates, behavioural and ecological variables have very low or negligible phylogenetic signals [61]; no analysis of primate behaviour and ecology with and without using phylogenetic methods has ever changed any results [62]. Nonetheless, to be sure that significance levels are not inflated by failure to control for phylogenetic effects, all analyses were run separately at group, species and genus levels.…”

Four errors and a fallacy: pitfalls for the unwary in comparative brain analyses

“…In practice, both EQ and ECV are poor estimates of the socially functional brain and hence yield only modest correlations with either ‘smart’ cognition (i.e. decision‐making competences) (Dunbar et al ., 2005; Deaner et al ., 2007; Shultz & Dunbar, 2010 c ) or social group size (Dunbar, 1992; Dunbar & Shultz, 2017, 2021 a ; Shultz & Dunbar, 2022) compared to indices based on neocortex size itself.…”