Access Type

Open Access Thesis

Date of Award

January 2015

Degree Type


Degree Name




First Advisor

Glenn E. Weisfeld


Across the animal kingdom, the sex that experiences the most reproductive variance tends to evolve sexually dimorphic traits—both behavioral and morphological—which aid in reproduction. Human evolution has been marked by greater male intrasexual selection and as a result, men display a variety of secondary sexual characteristics, putatively serving to enhance biological fitness. Among these, fundamental frequency, closely related to perception of pitch, among men is half that of women. Likewise, monotonicity, that is, variance in pitch across an utterance, is higher in men (i.e., women show greater variance in pitch) while formant dispersion, which gives the voice its timbre, is lower. The honesty of these vocal parameters as signaling mechanisms used in context of intrasexual competition has been investigated by a host of researchers; however no research to date has directly assessed the degree to which these parameters predict actual physical formidability, a key step in establishing the honesty of a signal. Here, I address this gap by testing whether these parameters are associated with fighting ability in a large sample of mixed martial arts fighters. Pitch, monotonicity, and timbre were extracted from interviews taken from 292 UFC® fighters and compared with the fighters’ records. Pitch and monotonicity were associated with formidability such that a more masculine profile was associated with higher formidability; timbre however was not associated with formidability. Taken together, these results indicate that pitch and monotonicity may be honest signals of physical formidability.