Mearing_et_al_2022.pdf (2.13 MB)
The evolutionary drivers of primate scleral coloration.
journal contribution
posted on 2023-07-26, 15:59 authored by Alex S. Mearing, Judith M. Burkart, Jacob Dunn, Sally E Street, Kathelijine KoopsThe drivers of divergent scleral morphologies in primates are currently unclear, though white sclerae are often assumed to underlie human hyper-cooperative behaviours. Humans are unusual in possessing depigmented sclerae whereas many other extant primates, including the closely-related chimpanzee, possess dark scleral pigment. Here, we use phylogenetic generalized least squares (PGLS) analyses with previously generated species-level scores of proactive prosociality, social tolerance (both n = 15 primate species), and conspecific lethal aggression (n = 108 primate species) to provide the first quantitative, comparative test of three existing hypotheses. The ‘self-domestication’ and ‘cooperative eye’ explanations predict white sclerae to be associated with cooperative, rather than competitive, environments. The ‘gaze camouflage’ hypothesis predicts that dark scleral pigment functions as gaze direction camouflage in competitive social environments. Notably, the experimental evidence that non-human primates draw social information from conspecific eye movements is unclear, with the latter two hypotheses having recently been challenged. Here, we show that white sclerae in primates are associated with increased cooperative behaviours whereas dark sclerae are associated with reduced cooperative behaviours and increased conspecific lethal violence. These results are consistent with all three hypotheses of scleral evolution, suggesting that primate scleral morphologies evolve in relation to variation in social environment.
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Refereed
- Yes
Volume
12Page range
14119Publication title
Scientific ReportsISSN
2045-2322External DOI
Publisher
Nature ResearchFile version
- Published version
Language
- eng
Legacy posted date
2022-09-16Legacy creation date
2022-09-16Legacy Faculty/School/Department
Faculty of Science & EngineeringUsage metrics
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