Total Sexual Selection on Men's Voices

Open Access
Author:
Bundy, Jason Nyerere
Area of Honors:
Bachelor of Philosophy
Degree:
Bachelor of Philosophy
Document Type:
Thesis
Thesis Supervisors:
  • David Andrew Puts, Thesis Supervisor
  • Richard Jon Stoller, Honors Advisor
Keywords:
  • voices
  • sexual dimorphism
  • pitch
  • monotonicity
  • formants
  • pitch variation
  • attractiveness
  • dominance
  • sexual selection
Abstract:
The human voice is particularly well suited for the study of sexual selection in humans. Vocal traits exhibit some of the largest human sex differences, these differences emerge during sexual maturation, and sexually differentiated vocal traits are linked to men’s mating and reproductive success. Men’s voices differ from women’s in pitch, timbre, and pitch variation. Prior experimental research has examined the influence of pitch and timbre on perceptions relevant to sexual selection, such as dominance and attractiveness, but the effects of pitch variation are unclear. Correlational research is also necessary to determine the relative importance of these different acoustic parameters in naturally varying speech, but prior correlational research is sparse and generally limited to estimating directional selection. We conducted two studies to fill these gaps in knowledge. In the first study, we manipulated pitch variation to observe its influence on perceptions of attractiveness, dominance, and prestige. In the second study, we examined linear, quadratic and interaction effects of all three parameters on perceptions of dominance and attractiveness. Experimentally manipulated pitch variation negatively, quadratically affected perceptions of attractiveness to women and dominance and prestige to other men. In regression models using naturally varying speech, mean pitch and timbre, but not pitch variation, predicted perceptions of dominance and attractiveness. Pitch negatively, linearly predicted dominance and attractiveness, and timbre negatively quadratically predicted attractiveness and negatively linearly predicted dominance. These results suggest that men’s vocal pitch and timbre signal dominance and mate quality, and that both inter- and intrasexual selection shaped men’s voices over human evolution.