Genetic influences on dentognathic morphology in the Jirel population of Nepal

Anna M. Hardin, Ryan P. Knigge, Dana L. Duren, Sarah Williams-Blangero, Janardan Subedi, Michael C. Mahaney, Richard J. Sherwood

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3 Scopus citations


Patterns of genetic variation and covariation impact the evolution of the craniofacial complex and contribute to clinically significant malocclusions in modern human populations. Previous quantitative genetic studies have estimated the heritabilities and genetic correlations of skeletal and dental traits in humans and nonhuman primates, but none have estimated these quantitative genetic parameters across the dentognathic complex. A large and powerful pedigree from the Jirel population of Nepal was leveraged to estimate heritabilities and genetic correlations in 62 maxillary and mandibular arch dimensions, incisor and canine lengths, and post-canine tooth crown areas (N ≥ 739). Quantitative genetic parameter estimation was performed using maximum likelihood-based variance decomposition. Residual heritability estimates were significant for all traits, ranging from 0.269 to 0.898. Genetic correlations were positive for all trait pairs. Principal components analyses of the phenotypic and genetic correlation matrices indicate an overall size effect across all measurements on the first principal component. Additional principal components demonstrate positive relationships between post-canine tooth crown areas and arch lengths and negative relationships between post-canine tooth crown areas and arch widths, and between arch lengths and arch widths. Based on these findings, morphological variation in the human dentognathic complex may be constrained by genetic relationships between dental dimensions and arch lengths, with weaker genetic correlations between these traits and arch widths allowing for variation in arch shape. The patterns identified are expected to have impacted the evolution of the dentognathic complex and its genetic architecture as well as the prevalence of dental crowding in modern human populations.

Original languageEnglish (US)
Pages (from-to)2137-2157
Number of pages21
JournalAnatomical Record
Issue number9
StatePublished - Sep 2022

Bibliographical note

Funding Information:
The Jiri Dental Study was made possible by the infrastructure provided by the long‐term efforts of the Jiri Helminth Study. In particular, we are grateful to Suman Jirel and Robin Singh Shrestha for overseeing the work in Jiri, Nepal, and to the dentists involved in the project, Dr. Reetu Shrestha and Dr. Om Rana. Drs. John Blangero and Tom Dyer provided assistance with analyses. The study was approved by the Nepal Health Research Council. These studies were supported by funding from the National Institute of Dental and Craniofacial Research (NIH) and the National Institute of Allergy and Infectious Disease (NIH). Finally, we are grateful to the people of Jiri, Nepal for their hospitality.

Publisher Copyright:
© 2022 American Association for Anatomy.


  • anatomically modern Homo sapiens
  • craniofacial evolution
  • dental evolution
  • genetic correlations
  • quantitative genetics


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