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Published on: November 6, 2014
Quantitative Genetic Analysis of Baboon Facial Variation Challenges a Classic Papionin Trait
A Thiebaut1, C C Roseman2, M C Mahaney3,4
1Centro Nacional de Investigación sobre la Evolución Humana, Paseo Sierra de Atapuerca 3, 09002 Burgos, Spain.
Integrative Organismal Biology (Oxford, England)
|July 13, 2026
Summary
The anteorbital drop (AOD) in baboons shows significant heritability but limited evolvability, challenging its use as a reliable phylogenetic character in paleontology. Further research is needed to understand its evolutionary significance.
Area of Science:
- Evolutionary biology
- Paleontology
- Quantitative genetics
Background:
- The Linnaean family of monkeys, including baboons, macaques, and mandrills, is characterized by varied muzzle shapes, specifically the anteorbital drop (AOD).
- The AOD is a phylogenetic character used in paleontological studies to describe lateral nasal dorsum profile variation.
Purpose of the Study:
- To devise a quantitative method for measuring the anteorbital drop (AOD).
- To assess the variation, heritability, and evolvability of the AOD in a pedigreed baboon colony.
- To evaluate the suitability of the AOD as a phylogenetic character for paleontological research.
Main Methods:
- Quantitative genetic analyses were performed using a MCMCglmm model.
- Facial variation data from a captive, pedigreed baboon colony (n=934) were analyzed.
- The study assessed the AOD's variation, genetic integration, and evolvability relative to other facial traits.
Main Results:
- The admixed baboon population exhibited significant AOD variation, exceeding that seen across papionin genera.
- The AOD was found to be highly heritable but less evolvable than other facial variations.
- Sex had minimal influence on AOD variation, unlike other facial measurements.
Conclusions:
- The AOD's high heritability and low evolvability, coupled with minimal sexual dimorphism, challenge its utility as a discrete phylogenetic character.
- The AOD variation likely arises from various non-sexually dimorphic processes influencing facial length.
- Quantitative genetic approaches can reveal the evolutionary relevance of traditional paleontological traits.
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