Grawunder, S. and Crockford, C. and Clay, Z. and Kalan, A. K. and Stevens, J. M. G. and Stoessel, A. and Hohmann, G. (2018) 'Higher fundamental frequency in bonobos is explained by larynx morphology.', Current biology., 28 (20). R1188-R1189.
Acoustic signals, shaped by natural and sexual selection, reveal ecological and social selection pressures . Examining acoustic signals together with morphology can be particularly revealing. But this approach has rarely been applied to primates, where clues to the evolutionary trajectory of human communication may be found. Across vertebrate species, there is a close relationship between body size and acoustic parameters, such as formant dispersion and fundamental frequency (f0). Deviations from this acoustic allometry usually produce calls with a lower f0 than expected for a given body size, often due to morphological adaptations in the larynx or vocal tract . An unusual example of an obvious mismatch between fundamental frequency and body size is found in the two closest living relatives of humans, bonobos (Pan paniscus) and chimpanzees (Pan troglodytes). Although these two ape species overlap in body size , bonobo calls have a strikingly higher f0 than corresponding calls from chimpanzees . Here, we compare acoustic structures of calls from bonobos and chimpanzees in relation to their larynx morphology. We found that shorter vocal fold length in bonobos compared to chimpanzees accounted for species differences in f0, showing a rare case of positive selection for signal diminution in both bonobo sexes.
|Full text:||(AM) Accepted Manuscript|
Available under License - Creative Commons Attribution Non-commercial No Derivatives.
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|Publisher Web site:||https://doi.org/10.1016/j.cub.2018.09.030|
|Publisher statement:||© 2018 This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/|
|Date accepted:||23 August 2018|
|Date deposited:||25 September 2018|
|Date of first online publication:||22 October 2018|
|Date first made open access:||22 October 2019|
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