Doctoral Dissertation Research: Vocal Communication and Dominance Rank in a Non-Human Primate

Social animals navigate a particularly complex environment in which their actions influence their social standing and reproductive success. Among their behavioral repertoire are poorly understood vocalizations that may relate to the complexity of social structures and the evolution of social organization. This doctoral dissertation research examines the vocalizations and hormonal levels of males from a highly competitive non-human primate species to determine whether vocalizations play a role in a male’s social rank and reproductive success. The study advances fundamental knowledge about animal communication, social evolution, and sexual selection. In addition, this research supports conservation efforts, provides scientific training, and promotes STEM education among K-12 and undergraduate students. This doctoral research project combines behavioral observations, acoustic analyses, and hormone assays to investigate if dominant males produce more frequent, diverse, and acoustically distinct calls linked to higher androgen levels. The research uses playback experiments by broadcasting recorded calls to other animals, assessing how individuals respond based on the caller’s rank and group membership. This experimental component reveals whether vocalizations alone communicate dominance and competitive ability in the study species. The project uses statistical models to assess relationships between vocalization features, hormone levels, and behavior while accounting for factors like group membership. This integrative approach advances the understanding of the ways in which sexual selection shapes communication strategies in primates. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.