Craniofacial Fluctuating Asymmetry in Gorillas, Chimpanzees, and Macaques

Authors

Ashly N. Romero, University of Arkansas
D. Rex Mitchell, Flinders University
Siobhán B. Cooke, Johns Hopkins University
Claire A. Kirchhoff, Marquette UniversityFollow
Claire E. Terhune, University of Arkansas

Document Type

Article

Publication Date

2-2022

Publisher

Wiley

Source Publication

American Journal of Biological Anthropology

Source ISSN

2692-7691

Abstract

Objectives

Craniofacial fluctuating asymmetry (FA) refers to the random deviations from symmetry exhibited across the craniofacial complex and can be used as a measure of developmental instability for organisms with bilateral symmetry. This article addresses the lack of data on craniofacial FA in nonhuman primates by analyzing FA magnitude and variation in chimpanzees, gorillas, and macaques. We offer a preliminary investigation into how FA, as a proxy for developmental instability, varies within and among nonhuman primates.

Materials and Methods

We generated 3D surface models of 121 crania from Pan troglodytes troglodytes, Gorilla gorilla gorilla, and Macaca fascicularis fascicularis. Using geometric morphometric techniques, the magnitude of observed FA was calculated and compared for each individual, sex, and taxon, along with the variation of FA across cranial regions and for each bilateral landmark.

Results

Gorillas and macaques exhibited higher and more similar magnitudes of FA to each other than either taxon did to chimpanzees; variation in magnitude of FA followed this same trend. No significant differences were detected between sexes using pooled data across species, but sex did influence FA magnitude within taxa in gorillas. Further, variation in FA variance across cranial regions and by landmark was not distributed in any particular pattern.

Conclusion

Possible environmentally induced causes for these patterns of FA magnitude include differences in growth rate and physiological stress experienced during life. Developmental stability may be greatest in chimpanzees in this sample. Additionally, these results point to appropriate landmarks for future FA analyses and may help suggest more urgent candidate taxa for conservation efforts.

Comments

Accepted version. American Journal of Biological Anthropology, Vol. 177, No. 2 (February 2022): 286-299. DOI. © 2022 Wiley. Used with permission.

Recommended Citation

Romero, Ashly N.; Mitchell, D. Rex; Cooke, Siobhán B.; Kirchhoff, Claire A.; and Terhune, Claire E., "Craniofacial Fluctuating Asymmetry in Gorillas, Chimpanzees, and Macaques" (2022). Biomedical Sciences Faculty Research and Publications. 207.
https://epublications.marquette.edu/biomedsci_fac/207