What can deer tell us about our voice? How sexual selection may have shaped human vocal diversity

Many animal species use vocal communication, but humans are unique in the ability to control the vocal production of an incredible diversity of sounds, enabling us to exchange information of extreme complexity. In this talk, I will propose that sexual selection, which is responsible for the evolution of astonishing visual and auditory signals in many animal species, may have played a key role in the emergence of our vocal diversity. I will show that in a wide range of polygynous species, sexual selection has modified the vocal apparatus of males to support the exaggeration of body size conveyed by vocalizations. These modifications have in turn opened up the acoustic space along a male/female continuum, where low frequencies convey dominance and/or masculinity, and high frequencies convey subordination and/or femininity. I will suggest that this widening of the vocal space, which can be found in modern humans in the expression of gender in children’s and adults’ voices, may have favored the evolution of vocal control by allowing us to play along this frequency continuum to signal emotions and motivations. I will also suggest that size exaggeration may even have shaped the evolution of mechanisms necessary for the production and perception of vowels in speech.