Chimpanzee (Pan troglodytes) gaze is conspicuous at ecologically-relevant distances
Abstract Chimpanzee (Pan troglodytes) sclera appear much darker than the white sclera of human eyes, to such a degree that the direction of chimpanzee gaze may be concealed from conspecifics. Recent debate surrounding this topic has produced mixed results, with some evidence suggesting that (1) prim...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Nature Portfolio
2022-06-01
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| Series: | Scientific Reports |
| Online Access: | https://doi.org/10.1038/s41598-022-13273-3 |
| _version_ | 1817968800412205056 |
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| author | Will Whitham Steven J. Schapiro Jolyon Troscianko Jessica L. Yorzinski |
| author_facet | Will Whitham Steven J. Schapiro Jolyon Troscianko Jessica L. Yorzinski |
| author_sort | Will Whitham |
| collection | DOAJ |
| description | Abstract Chimpanzee (Pan troglodytes) sclera appear much darker than the white sclera of human eyes, to such a degree that the direction of chimpanzee gaze may be concealed from conspecifics. Recent debate surrounding this topic has produced mixed results, with some evidence suggesting that (1) primate gaze is indeed concealed from their conspecifics, and (2) gaze colouration is among the suite of traits that distinguish uniquely social and cooperative humans from other primates (the cooperative eye hypothesis). Using a visual modelling approach that properly accounts for specific-specific vision, we reexamined this topic to estimate the extent to which chimpanzee eye coloration is discriminable. We photographed the faces of captive chimpanzees and quantified the discriminability of their pupil, iris, sclera, and surrounding skin. We considered biases of cameras, lighting conditions, and commercial photography software along with primate visual acuity, colour sensitivity, and discrimination ability. Our visual modeling of chimpanzee eye coloration suggests that chimpanzee gaze is visible to conspecifics at a range of distances (within approximately 10 m) appropriate for many species-typical behaviours. We also found that chimpanzee gaze is discriminable to the visual system of primates that chimpanzees prey upon, Colobus monkeys. Chimpanzee sclera colour does not effectively conceal gaze, and we discuss this result with regard to the cooperative eye hypothesis, the evolution of primate eye colouration, and methodological best practices for future primate visual ecology research. |
| first_indexed | 2024-04-13T20:13:36Z |
| format | Article |
| id | doaj.art-4ead4070821244b696bc035c5aecfe8a |
| institution | Directory Open Access Journal |
| issn | 2045-2322 |
| language | English |
| last_indexed | 2024-04-13T20:13:36Z |
| publishDate | 2022-06-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Scientific Reports |
| spelling | doaj.art-4ead4070821244b696bc035c5aecfe8a2022-12-22T02:31:46ZengNature PortfolioScientific Reports2045-23222022-06-011211710.1038/s41598-022-13273-3Chimpanzee (Pan troglodytes) gaze is conspicuous at ecologically-relevant distancesWill Whitham0Steven J. Schapiro1Jolyon Troscianko2Jessica L. Yorzinski3Department of Ecology and Conservation Biology, Texas A&M UniversityDepartment of Comparative Medicine, UT MD Anderson Cancer CenterCentre for Ecology and Conservation, University of ExeterDepartment of Ecology and Conservation Biology, Texas A&M UniversityAbstract Chimpanzee (Pan troglodytes) sclera appear much darker than the white sclera of human eyes, to such a degree that the direction of chimpanzee gaze may be concealed from conspecifics. Recent debate surrounding this topic has produced mixed results, with some evidence suggesting that (1) primate gaze is indeed concealed from their conspecifics, and (2) gaze colouration is among the suite of traits that distinguish uniquely social and cooperative humans from other primates (the cooperative eye hypothesis). Using a visual modelling approach that properly accounts for specific-specific vision, we reexamined this topic to estimate the extent to which chimpanzee eye coloration is discriminable. We photographed the faces of captive chimpanzees and quantified the discriminability of their pupil, iris, sclera, and surrounding skin. We considered biases of cameras, lighting conditions, and commercial photography software along with primate visual acuity, colour sensitivity, and discrimination ability. Our visual modeling of chimpanzee eye coloration suggests that chimpanzee gaze is visible to conspecifics at a range of distances (within approximately 10 m) appropriate for many species-typical behaviours. We also found that chimpanzee gaze is discriminable to the visual system of primates that chimpanzees prey upon, Colobus monkeys. Chimpanzee sclera colour does not effectively conceal gaze, and we discuss this result with regard to the cooperative eye hypothesis, the evolution of primate eye colouration, and methodological best practices for future primate visual ecology research.https://doi.org/10.1038/s41598-022-13273-3 |
| spellingShingle | Will Whitham Steven J. Schapiro Jolyon Troscianko Jessica L. Yorzinski Chimpanzee (Pan troglodytes) gaze is conspicuous at ecologically-relevant distances Scientific Reports |
| title | Chimpanzee (Pan troglodytes) gaze is conspicuous at ecologically-relevant distances |
| title_full | Chimpanzee (Pan troglodytes) gaze is conspicuous at ecologically-relevant distances |
| title_fullStr | Chimpanzee (Pan troglodytes) gaze is conspicuous at ecologically-relevant distances |
| title_full_unstemmed | Chimpanzee (Pan troglodytes) gaze is conspicuous at ecologically-relevant distances |
| title_short | Chimpanzee (Pan troglodytes) gaze is conspicuous at ecologically-relevant distances |
| title_sort | chimpanzee pan troglodytes gaze is conspicuous at ecologically relevant distances |
| url | https://doi.org/10.1038/s41598-022-13273-3 |
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