choose strategies linked to environmental conditions, whereas the optimal male strategy depends on the females’ distribution and behavior (Schuelke & Ostner, 2012). In general, safety, especially that of dependent offspring, is best achieved in groups, whereas foraging is more efficient when performed more solitarily. This is because in each group, food competition has both a contest (dominance) and scramble (pure group size effect, with dominance effect removed) component. Thus, in larger groups, all suffer more feeding competition than in smaller groups, although the burden usually falls more heavily on the subordinates. Females will thus adjust their behavior in order to find the optimal balance between the two. Where exactly this equilibrium is situated for a given species depends on further factors. For instance, body size and life history have an impact on susceptibility to, and acceptable risk of, predation. Similarly, when food is clumped and highly valuable this typically increases contest competition, which in stable and personalized societies tends to lead to the formation of dominance hierarchies. In societies with steep dominance hierarchies, valuable alliances, close bonds, female philopatry typically co-evolve (van Schaik, 1996). Finally, all factors cannot be considered in isolation, but need to be considered in their historical context. Evolutionary options are not equal for all species, but ancestral states heavily constrain the degrees of freedom for evolutionary trajectories. Primate social behavior, for instance, shows strong evidence for phylogenetic inertia (Shultz, Opie, & Atkinson, 2011). As a consequence, predicting the form of societies based on the costs and benefits of associating with others is far from straightforward. Nevertheless, the socio-ecological approach has been and still is a useful framework for investigating and understanding the evolution of sociality, and this approach has been particularly fruitful in primatology.
choose strategies linked to environmental conditions, whereas the optimal male strategy depends on the females’ distribution and behavior (Schuelke & Ostner, 2012). In general, safety, especially that of dependent offspring, is best achieved in groups, whereas foraging is more efficient when performed more solitarily. This is because in each group, food competition has both a contest (dominance) and scramble (pure group size effect, with dominance effect removed) component. Thus, in larger groups, all suffer more feeding competition than in smaller groups, although the burden usually falls more heavily on the subordinates. Females will thus adjust their behavior in order to find the optimal balance between the two. Where exactly this equilibrium is situated for a given species depends on further factors. For instance, body size and life history have an impact on susceptibility to, and acceptable risk of, predation. Similarly, when food is clumped and highly valuable this typically increases contest competition, which in stable and personalized societies tends to lead to the formation of dominance hierarchies. In societies with steep dominance hierarchies, valuable alliances, close bonds, female philopatry typically co-evolve (van Schaik, 1996). Finally, all factors cannot be considered in isolation, but need to be considered in their historical context. Evolutionary options are not equal for all species, but ancestral states heavily constrain the degrees of freedom for evolutionary trajectories. Primate social behavior, for instance, shows strong evidence for phylogenetic inertia (Shultz, Opie, & Atkinson, 2011). As a consequence, predicting the form of societies based on the costs and benefits of associating with others is far from straightforward. Nevertheless, the socio-ecological approach has been and still is a useful framework for investigating and understanding the evolution of sociality, and this approach has been particularly fruitful in primatology.