Primates September 2018

'''Pinheiro, T., & Lopes, M. A. (2018). Hierarchical structure and the influence of individual attributes in the captive squirrel monkey (Saimiri collinsi). Primates, 59, 475-482.'''

Social hierarchy in nonhuman primates is not confined to a single definition. The hierarchy that dominates the primate social network can differ depending on degree of linear arrangement, such as in partial hierarchies in which several members may occupy the same position, and the steepness of the hierarchy, which refers to the degree of distance between adjacent members. In a test of the prior-attributes model, positing that individual traits such as age and sex determine hierarchy position, Pinheiro and Lopes (2018) assessed the social hierarchy of captive squirrel monkeys along with relevant attributes, hierarchy steepness, and correlation with agonsitic behavior. It was found that the squirrel monkeys adhered to a partial hierarchy with a smooth dominance gradient that was not dependent on individual attributes such as sex, age, weight, or captive versus wild origin, with the exception of the males that occupied the highest position in the hierarchy possessing the largest body size of all other members. In addition, agonsitic behavior was found to correlate with position for males only. The authors suggest that the prior-attributes model does not apply to this species of squirrel monkey which may be due to similar body size between males and females. Further, the relation between hierarchy position and agonistic behavior in males suggests males of this species rely on threat and force to obtain and maintain social position while females may employ more affiliative strategies.