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The Nanny and Aural Sexual Selection

Sexual selection, like many evolutionary concepts, was first anticipated by Charles Darwin and has since been elaborated in great detail. It is a powerful concept, explaining everything from the unwieldy nature of the peacock to the changing curves of Playboy centerfolds over the years. But this is all selection at the visual level.

Just as certain appearances are more or less pleasing, there should also presumably be aural sexual selection, selection for or against certain sounds. And this happens too. There are mating calls in the wild and even cases when musical abilities among humans can be fitness advantages (e.g. guitar douchebag). But what about more subtle cases that might be selected against? For example, what about the Nanny, or at least Janice from Friends? Are certain voices or speaking styles, perhaps such as the aforementioned nasal and strongly accented, subject to sexual selection?

I recently asked Coren Apicella, a friend of mine who’s a biological anthropologist, about this. And happily, it turns out that there is a burgeoning body of research in this area. Coren studies the Hadza, a hunter-gatherer group in Tanzania, and works with them to better understand natural selection. She has examined how pitch affects reproductive fitness of men and women, using the lens of sexual dimorphism.

Sexual dimorphism is the difference in appearance or other observable traits between males and females of a single species (for examples, take a look at the many pictures in the Wikipedia article). When it comes to humans, in addition to men and women looking different, we also sound different: men have deeper voices. Coren found that, among other results, Hadza men with deeper voices do indeed have greater reproductive success and men prefer to marry women with more highly pitched voices. Intriguingly though, there is still debate about where this dimorphism arose: is it due to the choice of women of who to mate with, or competition between men? But whatever the mechanism, sexual selection on voice is clearly at work.

Unfortunately, it seems that studies haven’t been done yet on more nuanced voice traits, such as accents. But it is heartening to know that evolution has infiltrated both sight and sound. Of course, sexual selection is far from destiny. There are many people who appreciate the Nanny or other “distinctively” voiced individuals, just as many other sitcom characters are able to be quite picky regarding those traits both audio and visual.

Apicella, C., Feinberg, D., & Marlowe, F. (2007). Voice pitch predicts reproductive success in male hunter-gatherers Biology Letters, 3 (6), 682-684 DOI: 10.1098/rsbl.2007.0410

Apicella, C., & Feinberg, D. (2009). Voice pitch alters mate-choice-relevant perception in hunter–gatherers Proceedings of the Royal Society B: Biological Sciences, 276 (1659), 1077-1082 DOI: 10.1098/rspb.2008.1542