Forager-horticulturists: Lowering the voice fundamental frequency in audio clips of men speaking increased perceptions of fighting ability but did not affect perceptions of prestige and decreased their attractiveness to women

Sexual selection for low male voice pitch among Amazonian forager-horticulturists. Kevin A. Rosenfield et al. Evolution and Human Behavior, Volume 41, Issue 1, January 2020, Pages 3-11. https://doi.org/10.1016/j.evolhumbehav.2019.07.002

Abstract: Pitch is the most perceptually salient feature of the voice, yet it is approximately five standard deviations lower in men than in women, a degree of sexual dimorphism exceeding that of all extant nonhuman apes. Evidence from Western samples suggests that low-frequency vocalizations may have augmented male mating success ancestrally by intimidating competitors and/or attracting mates. However, data are lacking from small-scale societies. We therefore investigated sexual selection on male pitch (measured by fundamental frequency, fo) in a population of Bolivian forager-horticulturists, the Tsimané. We found that experimentally lowering fo in audio clips of men speaking increased perceptions of fighting ability but did not affect perceptions of prestige and decreased their attractiveness to women. Further, men with lower speaking fo reported higher numbers of offspring, and this was mediated by the reproductive rates of men's wives, suggesting that men with lower fo achieved higher reproductive success by having access to more fertile mates. These results thus provide new evidence that men's fo has been shaped by intrasexual competition.