Facial asymmetry tracks genetic diversity among Gorilla subspecies

Kate McGrath, Amandine B. Eriksen, Daniel García-Martínez, Jordi Galbany, Aida Gómez-Robles, Jason S. Massey, Lawrence M. Fatica, Halszka Glowacka, Keely Arbenz-Smith, Richard Muvunyi, Tara S. Stoinski, Michael R. Cranfield, Kirsten Gilardi, Chantal Shalukoma, Emmanuel De Merode, Emmanuel Gilissen, Matthew W. Tocheri, Shannon C. McFarlin, Yann Heuzé

Research output: Contribution to journalArticlepeer-review


Mountain gorillas are particularly inbred compared to other gorillas and even the most inbred human populations. As mountain gorilla skeletal material accumulated during the 1970s, researchers noted their pronounced facial asymmetry and hypothesized that it reflects a population-wide chewing side preference. However, asymmetry has also been linked to environmental and genetic stress in experimental models. Here, we examine facial asymmetry in 114 crania from three Gorilla subspecies using 3D geometric morphometrics. We measure fluctuating asymmetry (FA), defined as random deviations from perfect symmetry, and population-specific patterns of directional asymmetry (DA). Mountain gorillas, with a current population size of about 1000 individuals, have the highest degree of facial FA (explaining 17% of total facial shape variation), followed by Grauer gorillas (9%) and western lowland gorillas (6%), despite the latter.

Original languageEnglish (US)
Article number20212564
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1969
StatePublished - 2022
Externally publishedYes


  • asymmetry
  • geometric morphometrics
  • great apes
  • inbreeding
  • stress

ASJC Scopus subject areas

  • Immunology and Microbiology(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Environmental Science(all)
  • Agricultural and Biological Sciences(all)


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