Benedict Cumberbatch’s deep and booming voice might have made him a hit among women, but a low pitch is more likely to have evolved to intimidate other men, new research suggests.

When both heterosexual men and women were played recordings of male voices, the deeper tones were hailed by men as sounding more dominant. While the deeper voices were judged to be more attractive by female listeners, the effect was weaker, the researchers report.

“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,” said David Puts of Pennsylvania State University, who led the study.

Published in Proceedings of the Royal Society B: Biological Sciences, the three-part study by an international team of scientists explored the links between voice pitch and mating systems, attractiveness and, for males only, perceived dominance.



In the first leg of the research, the scientists turned their attention to primates encompassing Old and New World monkeys, as well as humans and other apes, to explore differences in “fundamental frequency” between males and females of each species - the aspect of the voice that is perceived as pitch.



After selecting 1721 recordings, they found large differences were more common in polygynous species - where males mate with more than one female - than monogamous ones. That, they say, could be because in polygynous species, competition between males is greater - hence a male with a lower-pitched voice deemed to be intimidating could have the edge in securing a mate. Intriguingly, the researchers found that among the apes humans showed the greatest difference in pitch between the sexes, suggesting our ancestors were not searching for “the one” but were polygynous - a situation Puts still believes to be the case.

“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,” said Puts. “So what you get is a mating system that is effectively moderately polygynous even in monogamous societies.”

The results, say others, are unexpected. “While anthropologists document the variety of human ‘mating systems’, humans are most often regarded as following monogamous relationships,” said David Perrett, professor of psychology at the University of St Andrews. “The findings that sexual difference in voice pitch are marked in humans compared with other primates is therefore a surprise,” he added.

In the second experiment, 258 women and 175 men were recorded reading the same piece of text. For each female voice recorded, 15 men then rated it for attractiveness on a seven-point scale, both with a view to short and long term relationships, while each male voice was similarly rated by 15 women. In addition each male voice recording was rated for “dominance” by 15 men.

The researchers found that while the depth of the female voices did not affect how attractive they were deemed by male listeners, the situation was very different for the male voices. Deeper male voices were rated as more dominant by men and more attractive by women.



But when the scientists probed deeper into the results, they found the link to dominance to be up to three times stronger than the link to attractiveness. That, they say, suggests that the evolution of male pitch might have been influenced more by competition between males than by female choice when picking a mate.

“It’s not to say that our male ancestors were unabatedly at one another’s throats - lots of physical competition across a variety of species takes the form of threats and advertisement of dominance,” said Puts. Puts believes it is possible that traits such as a deeper voice allowed men to appear bigger and more dominant, without the need to resort to fighting. “This may have been even more important as we developed lethal, hand-held weapons,” he added.

A third experiment showed that in men with low levels of the stress hormone cortisol, a higher level of testosterone was linked to a deeper voice.



“Men who have higher testosterone and lower cortisol have a stronger immune response,” said Puts. With the new research revealing that these hormones are also linked to the depth of a man’s voice, Puts believes that a low pitch could indicate to women that a man is in fine fettle. “It may indicate their possession of a healthy immune system which would provide genes for producing a healthy immune system to their offspring,” he said.



But there could be other factors at play. “In humans it is likely both men and women have a choice in selection of their mate,” said Perrett. “Some of the explanation for the difference between men and women’s voice pitch might come from the selection by males of women with relatively high pitched voices rather than all of the selection being down to men fighting men and women choosing the victors.”