Meeting Abstract

P3.1  Wednesday, Jan. 6  How is the Primate Brain influenced by Physical Competition’s Intensity? CUNNINGHAM, Christopher/B*; CARRIER, David/R; University of Utah; University of Utah c.cunningham@utah.edu

Primates have relatively large brains. Physical male-male competition may have helped drive enlargement of the primate brain because aggressive conflicts entail extensive cognitive interactions; including perception, assessment, reasoning, and neuromotor coordination. This leads to the question: Do primate species that exhibit higher levels of physical male-male competition intensity have larger relative brains sizes. To address this prediction, we examined the correlation between brain size and three reliable indicators of physical male-male competition intensity: body mass-/canine height-sexual dimorphism, and relative male maxillary canine height. Analyses were conducted with phylogenetically independent contrast values. Significant, positive correlations exist between brain size and body mass sexual dimorphism within All Primates, Strepsirrhines, Haplorhines, New World monkeys, and Old World monkeys. Significant, positive correlations were also seen between brain size and maxillary canine sexual dimorphism within All Primates, Haplorhines, and Old World monkeys. In conclusion, brain size is positively correlated with male-male competition overall; however, there can be some variability within specific phylogenetic sub-groupings. These correlations are consistent with the hypothesis that sexual selection pressures due to physical competition among males are partially responsible for the large brains of primates.