UC Santa Barbara

There are competing hypotheses regarding the nature of information in multiple sexually selected traits in humans: the Redundant Signal Hypothesis (RSH), which argues they contain the same information, and the Multiple Message Hypothesis (MMH) argues they signal different information. Theory explaining why multiple traits evolved is lacking; male intrasexual competition may answer this question; evidence for pathogen-mediated sexual selection also exists. This thesis aims to explain the nature of information and why they evolved. The study manipulated facial and vocal masculinity orthogonally and concurrently. Women preferred men with high masculinity faces as short- and long-term potential mates, in terms of fighting ability, health and masculinity. Small main effects for vocal masculinity were found. These findings provided modest support for the RSH and MMH in an interaction between facial and vocal masculinity on fighting ability. Males low on facial and vocal masculinity were judged particularly low. There was also evidence increasingly unrestricted socio-sexuality was associated with increased preferences for facial masculinity.