What is it that determines who we choose as a mate? Physical attractiveness, height, hair color, strength and agility?
New research indicates that humans may have an innate preference for partners with certain vocal qualities.
Harvard University Anthropologist Coren Apicella spent time living with and studying a small tribe in Tanzania called the Hadza, which she says is one of the last "populations that practice traditional foraging and hunting techniques that are left on the planet."
Apicella says the Hadza provide a window to our past. "They live just like we would have lived, our ancestors would have lived, about 200,000 years ago."
Because the Hadza do not use any form of modern birth control, Apicella says they're a good population to study if you want to look at the reproductive outcomes of certain behaviors.
She recorded the voices of about 50 men and 50 women and then questioned all of them about their reproductive histories. "We found that men who have deeper voices have more babies, and they have more surviving children as well," she says, adding it's not clear why the deeper voiced men were so much more successful at reproducing.
"Maybe they have greater access to mates, and therefore they're able to have more children," she speculates. "Or perhaps, ... it has something to do with testosterone. These men who have lower-pitched voices have higher levels of testosterone."
Apicella suggests higher testosterone may make the men better hunters. "They're able to bring home more food to their families, and, therefore, their wives perhaps have shorter inter-birth intervals and can resume ovulation more quickly." That, she says, would lead to more children.
Another possibility, Apicella says is that deeper-voiced men "start reproducing at an earlier age, and they sort of get a head start." Or, she says, "It could be all these sorts of reasons."
Apicella reports the women were more attracted to the men with lower pitched voices. She says women actually perceived men who had deeper-pitched voices to be better hunters.
Apicella suggests that over the millennia, these innate preferences gave men with lower pitched voices an evolutionary advantage: they mated more often and more successfully. As a result, the trait for low-pitched voice was preferentially handed down from generation to generation.
Vocal quality was not a one-way preference either. Hadza men found women with higher pitched voices to be more feminine, and more beautiful.
Apicella's study is published in the journal Biology Letters.