Many of us consider a deep baritone voice to be romantic. The distinctive low octave sounds, often linked to Johnny Cash, Isaac Hayes, and Barry White, are inexplicably alluring to women, conveying attractiveness, confidence, and overall sex appeal. However, a recent study published in the journal Proceedings of the Royal Society B: Biological Sciences suggests deep male voices actually evolved for the purpose of exerting male dominance, not attracting women.

“If you look at what men’s traits look like they are designed for, they look much better designed for intimidating other males than for attracting females,” David Puts of Pennsylvania State University, who led the study, told The Guardian.

In a three-part study, Puts and his colleagues explored the links between vocal pitch, mating systems, attractiveness, and, in men only, perceived dominance.

They began by analyzing over 1,700 audio recordings of Old and New World monkeys, as well as humans and other apes, to measure differences in “fundamental frequency” between males and females. Fundamental frequency is the component of their voices that define pitch. It turned out that polygynous species — where males mate with more than one female — showed larger differences in fundamental frequency than monogamous ones.

Since competition between males is greater in polygynous species, the researchers theorized that males with a lower-pitched voice could be considered more intimidating, giving them a competitive edge when it came to securing a mate. Altogether, apes and humans showed the greatest differences in pitch between the sexes, suggesting we may not have evolved to be monogamous.

Puts used divorce as an example of this theory: “Even in societies that only have monogamous marriage, men are more likely to marry again after divorce, are likely to marry a younger wife and more likely than women to reproduce again with their new spouse,” he said. “So what you get is a mating system that is effectively moderately polygynous even in monogamous societies.”

Next, the researchers recorded over 200 women and nearly 200 men while reading the same piece of text. For each woman, 15 men were asked to rate their voice for attractiveness on a seven-point scale, as well as rate their view on short- and long-term relationships. The roles were then flipped, and each man was rated by 15 women for attractiveness. This time, however, 15 men were also assigned for each man to rate his voice for perceived dominance.

Unsurprisingly, the depth of female voices had no effect on perceived attractiveness. But when it came to men’s voices, men tended to rate the deeper vocal ranges as more dominant while the women rated them as more attractive. In fact, men considered deep voices dominant three times more than women found them attractive. Previous research has found men with deep voices are judged as more attractive because they suggest the speaker is strong and physically built, a perception that could also deter male competition.

In a final experiment, the researchers found men with low levels of cortisol, the stress hormone, and higher levels of testosterone were more likely to have deeper voices. There is an undeniable link between testosterone levels and vocal pitch, as rising levels of the male hormone during puberty trigger changes in the larynx and vocal cords, leading to lower-pitched voices. Additionally, men with higher testosterone levels and low cortisol possess a stronger immune system, suggesting that women see these men as having good genes — an evolutionary advantage.

That said, a 2011 study found men with deeper voices tended to have lower sperm quality than men with high-pitched voices. The sperm samples were considered to be “perfectly motile” and fertile, but the cells’ population density wasn’t as high. So, while having a deeper voice may give someone a higher perceived status, it doesn’t necessarily dictate their other capabilities.

Source: Puts DA, Hill AK, Walker RS et al. Sexual selection on male vocal fundamental frequency in humans and other anthropoids. Proceedings of the Royal Society B: Biological Sciences. 2016.