Men with deep voice may be lacking in sperm: study

The study, led by evolutionary biologist Leigh Simmons from the University of Western Australia looked at 54 heterosexual men between the ages of 18 and 32 and 30 heterosexual women from a local college campus.

The researchers recorded the voices of the men and then had the female participants rate the voices in terms of masculinity and attractiveness. As expected, the majority of the women voted the deep voices more attractive.

Next, the researchers had each male participant provide a semen sample to the lab. Each sample was entered into a sperm-analysis system which rated the sperm on its ability to swim toward a female’s egg. They also examined sperm count.

The results of the analysis showed that the men with deeper voices produced ejaculate with fewer sperm cells than the men with higher pitched voices.

The research suggests that the link between deep voices and a decline in sperm may be an evolutionary trade-off. Traits such as the deep voice which tend to be associated with success and dominance are traded for a low sperm count. While testosterone does play a role in the creation of sperm, too much can impair sperm production.

While those men with the deeper voices did show lower sperm counts than the other men participating, all sperm counts measured in the study were within healthy parameters.

More information: Simmons LW, Peters M, Rhodes G (2011) Low Pitched Voices Are Perceived as Masculine and Attractive but Do They Predict Semen Quality in Men? PLoS ONE 6(12): e29271. doi:10.1371/journal.pone.0029271

Abstract
Women find masculinity in men's faces, bodies, and voices attractive, and women's preferences for men's masculine features are thought to be biological adaptations for finding a high quality mate. Fertility is an important aspect of mate quality. Here we test the phenotype-linked fertility hypothesis, which proposes that male secondary sexual characters are positively related to semen quality, allowing females to obtain direct benefits from mate choice. Specifically, we examined women's preferences for men's voice pitch, and its relationship with men's semen quality. Consistent with previous voice research, women judged lower pitched voices as more masculine and more attractive. However men with lower pitched voices did not have better semen quality. On the contrary, men whose voices were rated as more attractive tended to have lower concentrations of sperm in their ejaculate. These data are more consistent with a trade off between sperm production and male investment in competing for and attracting females, than with the phenotype-linked fertility hypothesis.

Journal reference: PLoS ONE

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