TORONTO (Reuters Life!) - Forget the handsome face, broad shoulders or flirty grin, a deep voice is what attracts women and makes men likely to have more children, researchers said on Tuesday.

"We think it's sort of like a peacock's tail," said David Feinberg, an assistant professor at McMaster University in Ontario, Canada.

"A peacock's tail doesn't help a peacock survive in the world at all. All it really does is it's there to attract women. So in this case it's testosterone which masculinizes the voice at puberty," he said in an interview.

The study, published in the journal Biology Letters, showed that men with deep voices had greater reproductive success with women than their higher-pitched counterparts.

Coren Apicella, of Harvard University, interviewed 49 men and 52 women ranging in age from 18 to 55 from the Hadza tribe of Tanzania. It is one of the last hunter-gatherer tribes in the world and does not have access to birth control.

She recorded the pitch frequency of the men and women while they spoke about their reproductive history in their native Swahili.

When Apicella, Feinberg and Frank Marlowe of Florida State University analyzed the recordings they found that the deep-voiced men fathered more children.

The man in the study with the deepest voice had 10 children, nine of which were still alive, while the man with the highest voice had one surviving child from three.

"Maybe these men who have lower voice pitch are more attracted to women, they have higher testosterone levels and they're able to have greater access to mate," said Apicella.

She also suggests men with higher testosterone may be better hunters or that they reproduce earlier than other men.

The findings of the women were inconclusive, which may be because they are more limited reproductively, according to Apicella.

"They can't go out and have 20 children. They don't have the time and energy and resources to do all that. It could be that there is an effect but it's too subtle to detect in one generation," she explained.

So, does that mean men with a noticeably higher pitched voice are reproductively inadequate?

"No, not at all," said Feinberg, whose previous studies showed that women are more attracted to men with lower-pitched voices, while men prefer the faces of women with higher-pitched voices.

Men with higher levels of testosterone are also more at risk of putting themselves in danger -- physically and sexually, said Feinberg.

"People are looking for the best of both worlds," he said.

"In many cases, it's more desirable to get someone who's going to stick around, to help raise the kids and things like that. Those are admirable qualities."