Linking human male vocal parameters to perceptions, body morphology, strength and hormonal profiles in contexts of sexual selection

Christoph Schild,David A Puts,Rodrigo A Cardenas,Toe Aung,Tobias L Kordsmeyer,Lars Penke

doi:10.1038/s41598-020-77940-z

Abstract

Sexual selection appears to have shaped the acoustic signals of diverse species, including humans. Deep, resonant vocalizations in particular may function in attracting mates and/or intimidating same-sex competitors. Evidence for these adaptive functions in human males derives predominantly from perception studies in which vocal acoustic parameters were manipulated using specialist software. This approach affords tight experimental control but provides little ecological validity, especially when the target acoustic parameters vary naturally with other parameters. Furthermore, such experimental studies provide no information about what acoustic variables indicate about the speaker—that is, why attention to vocal cues may be favored in intrasexual and intersexual contexts. Using voice recordings with high ecological validity from 160 male speakers and biomarkers of condition, including baseline cortisol and testosterone levels, body morphology and strength, we tested a series of pre-registered hypotheses relating to both perceptions and underlying condition of the speaker. We found negative curvilinear and negative linear relationships between male fundamental frequency (fo) and female perceptions of attractiveness and male perceptions of dominance. In addition, cortisol and testosterone negatively interacted in predicting fo, and strength and measures of body size negatively predicted formant frequencies (Pf). Meta-analyses of the present results and those from two previous samples confirmed that fonegatively predicted testosterone only among men with lower cortisol levels. This research offers empirical evidence of possible evolutionary functions for attention to men’s vocal characteristics in contexts of sexual selection.

Highlights

Sexual selection appears to have shaped the acoustic signals of diverse species, including humans
Despite the abundance of evidence linking acoustic parameters to perceptions relevant in mating competition, a fundamental question remains: Why have humans evolved to attend to these parameters? Costly signaling theory which concerns the transmission of reliable information between signalers and receivers, is a useful theoretical tool to answer this question and helps us understand the maintenance of signal honesty via receiver-independent and receiver-dependent costs
Because the curvilinear relationship between long-term attractiveness and predicted formant frequencies (Pf) was significant, we investigated whether the linear term of fo and the quadratic term of Pf were independent predictors of long-term attractiveness

Summary

Introduction

Sexual selection appears to have shaped the acoustic signals of diverse species, including humans. Resonant vocalizations in particular may function in attracting mates and/or intimidating samesex competitors Evidence for these adaptive functions in human males derives predominantly from perception studies in which vocal acoustic parameters were manipulated using specialist software. This approach affords tight experimental control but provides little ecological validity, especially when the target acoustic parameters vary naturally with other parameters. From hearing the voice alone, humans can assess diverse salient social characteristics of a speaker, such biological sex, age and physical s trength[7,8,9] Many of these evaluations rely on inter-individual variation in specific sets of vocal parameters, including fundamental frequency and formant frequencies[5,10]. Links between formants and physical strength are equivocal[6,32]

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