Voice pitch predicts reproductive success in male hunter-gatherers

Abstract

The validity of evolutionary explanations of vocal sexual dimorphism hinges upon whether or not individuals with more sexually dimorphic voices have higher reproductive success than individuals with less dimorphic voices. However, due to modern birth control methods, these data are rarely described, and mating success is often used as a second-rate proxy. Here, we test whether voice pitch predicts reproductive success, number of children born and child mortality in an evolutionarily relevant population of hunter-gatherers. While we find that voice pitch is not related to reproductive outcomes in women, we find that men with low voice pitch have higher reproductive success and more children born to them. However, voice pitch in men does not predict child mortality. These findings suggest that the association between voice pitch and reproductive success in men is mediated by differential access to fecund women. Furthermore, they show that there is currently selection pressure for low-pitch voices in men.

Figure 1

Residuals from regression of reproductive success on age plotted against voice pitch. This scatter plot shows a negative relationship between male voice pitch and reproductive success.

Figure 2

Residuals from regression of the number of children born on age plotted against voice pitch. This scatter plot shows a negative relationship between male voice pitch and the number of children born. Note that this relationship remains unchanged when the person with most children born is removed from the analysis.