Group Size and Mating Preferences Drive Deeper Male Voices
hubie writes:
Deeper male voices in primates, including humans, offer more than sex appeal - they may have evolved as another way for males to drive off competitors in large groups that favored polygyny, or mating systems where a male has multiple mates, according to researchers. The research is the most comprehensive investigation of differences in vocal pitch between sexes to date and has the potential to help to shed light on social behavior in humans and their closest living relatives.
The average speaking pitch of an adult male human is about half the average pitch, an octave lower, than that of an adult female human, said David Puts, professor of anthropology at Penn State and study co-author.
"It's a sex difference that emerges at sexual maturity across species and it probably influences mating success through attracting mates or by intimidating competitors," he said. "I thought it has to be a trait that's been subjected to sexual selection, in which mating opportunities influence which traits are passed down to offspring. Humans and many other primates are highly communicative, especially through vocal communication. So it seems like a really relevant trait for thinking about social behavior in humans and primates in general."
The researchers used specialized computer software to visualize vocalizations and measure voice pitch in recordings from 37 anthropoid primate species, or those most closely related to humans, including gorillas, chimpanzees and recordings of 60 humans evenly divided by sex. Samples for each species included at least two male and two female vocal recordings, for a total of 1,914 vocalizations. The team then calculated average male and female vocal fundamental frequency for each species to see how pronounced the difference was between sexes.
[...] The researchers used these data to test five hypotheses simultaneously to identify which factors may have played the strongest roles in driving sex differences in vocal pitch. The hypotheses were: intensity of mating competition, large group size, multilevel social organization, trade-off against the intensity of sperm competition, and poor acoustic habitats. Previous research has looked at one or two of these hypotheses at a time. The current study is the first to test multiple hypotheses simultaneously for vocal pitch differences using a robust dataset, ensuring data consistency and garnering convincing results, according to Puts.
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