The “Walrus of Love” owed his sex appeal to evolution: women are programmed to prefer the deep tones of a Barry White to men with higher voices such as James Blunt and David Beckham, research has suggested.

A study of a hunter-gatherer tribe in Tanzania has found that men with bass voices have more children than those with higher pitched tones, because they have more sexual success with young and fertile women.

The results suggest that deep male voices have evolved because women find them more attractive, causing baritones to have more children on average than squeaky-voiced men.

The difference in pitch between male and female voices may thus be an example of runaway sexual selection, a phenomenon in which even a slight preference by one sex for a physical feature found in the other can lead to considerable changes in physiology.

“The results of this study have implications for the evolution of vocal dimorphism,” Coren Apicella of Harvard University, who led the research, said. “While we don’t know the exact reason that these men with deeper voices have fathered more children, it may be that they have increased access to mates, begin reproducing at an earlier age or their wives have shorter inter-birth intervals because they provide more food to them.

“It’s possible that vocal dimorphism has evolved over thousands of years, partly due to mate selection. Perhaps, at one time, men and women’s voices were closer in pitch than they are today.”

For the study, the results of which are published in the journal Biology Letters, the researchers investigated voice pitch and reproductive success in the Hadza tribe.

The Hadza follow a hunter-gatherer lifestyle that is similar to that of early human beings, with women gathering berries and digging for tubers while men hunt animals and collect honey.

The Hadza have a monogamous mating structure, in which marriage is voluntary, though extra-marital affairs and divorce are common. This makes them ideal for studying the effects on reproductive success of attributes such as voice pitch, as both sexes have a large degree of choice over with whom they mate.

The scientists asked 49 men and 52 women aged between 18 and 55 to name all their living and dead children. They were recorded saying the Swahili word for “hello”, and the tapes were analysed digitally for frequency.

After adjustments were made for age, men with a lower vocal pitch were found to have had more children than men with higher voices. Voice pitch did not affect female reproductive success.

The researchers said that the likeliest explanation was that women prefer men with lower voices, and therefore these men can have a wider pick of sexual partners and tend to choose the young and fertile.

“Based on these findings, we speculate that the associations reported between reproductive success and voice pitch in men are probably mediated by greater access to fecund women,” they said.

The female preference may have evolved because voice pitch is linked to male hormone levels, and in a hunter-gatherer society higher testosterone is a valuable attribute because more aggressive men are more likely to be successful hunters.

Previous research at the University of St Andrews has indicated that women tend to prefer deep male voices during the most fertile phase of their menstrual cycle.

The research team now plans to investigate the phenomenon further, to assess whether Hadza women indeed think of men with lower voices as better marriage partners or hunters.

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