Scleral pigmentation leads to conspicuous, not cryptic, eye morphology in chimpanzees
Open accessAbstract
Gaze following has been argued to be uniquely human, facilitated by our depigmented, white sclera [M. Tomasello, B. Hare, H. Lehmann, J. Call, J. Hum. Evol. 52, 314–320 (2007)]—the pale area around the colored iris—and to underpin human-specific behaviors such as language. Today, we know that great apes show diverse patterns of scleral coloration [J. A. Mayhew, J. C. Gómez, Am. J. Primatol. 77, 869–877 (2015); J. O. Perea García, T. Grenzner, G. Hešková, P. Mitkidis, Commun. Integr. Biol. 10, e1264545 (2016)]. We compare scleral coloration and its relative contrast with the iris in bonobos, chimpanzees, and humans. Like humans, bonobos’ sclerae are lighter relative to the color of their irises; chimpanzee sclerae are darker than their irises. The relative contrast between the sclera and iris in all 3 species is comparable, suggesting a perceptual mechanism to explain recent evidence that nonhuman great apes also rely on gaze as a social cue.
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The iris of the bonobo is darker than that of the chimpanzee.
“Perea-García et al. [9], which showed that the iris of the bonobo is darker than that of the chimpanzee.”
From Are dark-eyed dogs favoured by humans? Domestication as a potential driver of iris colour difference between dogs and wolves (2023) · cites this paper as [9]
Bonobos have darker iris (and lighter sclera), while chimpanzees have lighter iris (and darker sclera).
“Perea-García et al. [9] demonstrate that bonobos have darker iris (and lighter sclera), while chimpanzees have lighter iris (and darker sclera).”
From Are dark-eyed dogs favoured by humans? Domestication as a potential driver of iris colour difference between dogs and wolves (2023) · cites this paper as [9]
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Cites
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Ocular pigmentation in humans, great apes, and gibbons is not suggestive of communicative functions
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- Authors
- Perea-García, J. O., Kret, M. E., Monteiro, A., & Hobaiter, C.
- Affiliations
- Department of Biological Sciences, National University of Singapore, Singapore 117557;
- Leiden University (NL)
- National University of Singapore (SG)
- University of St Andrews (GB)
- Venue
- Proceedings of the National Academy of Sciences
- Publisher
- National Academy of Sciences
- Published
- 2019-09-03
- Volume
- 116
- Issue
- 39
- Pages
- 19248-19250
- ISSN
- 0027-8424 (ISSN-L)
- 1091-6490
- PMC
- PMC6765245
- OpenAlex
- W2971661919
- Cited by
- 62
- References
- 17
- Citations by year
- 2026: 3 · 2025: 4 · 2024: 3 · 2023: 24 · 2022: 12 · 2021: 12 · 2020: 4
- FWCI
- 8.79
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- Locations
- Proceedings of the National Academy of Sciences (publishedVersion, cc-by-nc-nd)
- Europe PMC (PubMed Central) (publishedVersion, cc-by-nc-nd)
- PubMed Central (publishedVersion, cc-by-nc-nd)
- PubMed (publishedVersion)
- Leiden Repository (Leiden University) (submittedVersion, cc-by-nc-nd)
- Acceda (Universidad de Las Palmas de Gran Canaria) (submittedVersion)
- St Andrews Research Repository (St Andrews Research Repository) (submittedVersion, cc-by-nc-nd)
- Data Archiving and Networked Services (DANS) (submittedVersion, other-oa)
- Funders
- Royal Zoological Society of Scotland
- Topics
- Social Sciences › Psychology › Social Psychology › Primate Behavior and Ecology
- Social Sciences › Psychology › Experimental and Cognitive Psychology › Evolutionary Psychology and Human Behavior
- Life Sciences › Neuroscience › Cognitive Neuroscience › Face Recognition and Perception
- Keywords
- scleral pigmentation, iris, gaze following, eye morphology, chimpanzees, bonobos, great apes, social cognition, gaze perception, human evolution
- MeSH terms
- Animals, Pan troglodytes, Eye, Eye Movements, Humans, Iris, Pigmentation, Sclera, Species Specificity, Pan paniscus
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