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A group-specific arbitrary tradition in chimpanzees (Pan troglodytes).
Edwin J C van Leeuwen1, Katherine A Cronin, Daniel B M Haun
1Max Planck Institute for Psycholinguistics, Max Planck Institute for Evolutionary Anthropology, PO Box 310, 6500 AH, Nijmegen, The Netherlands, ejcvanleeuwen@gmail.com.
Animal Cognition
|June 12, 2014
Summary
Chimpanzees spontaneously copy behaviors like the "grass-in-ear" display, even without apparent adaptive value. This study documents naturally occurring traditions in chimpanzee social learning.
Area of Science:
- Primate Behavior
- Ethology
- Cognitive Ecology
Background:
- Social learning is well-established in chimpanzees, with various known mechanisms.
- However, spontaneously emerging traditions in wild chimpanzee communities are rarely documented.
- Understanding natural traditions is crucial for assessing the real-world significance of social learning in animals.
Purpose of the Study:
- To document a spontaneously emerging tradition in a chimpanzee community.
- To investigate the social transmission of a seemingly non-adaptive behavior.
- To differentiate between learned traditions and ecologically determined behaviors.
Main Methods:
- A year-long daily focal follow study was conducted on a group of 12 chimpanzees.
- Observed and recorded the occurrence and spread of the "grass-in-ear" behavior.
- Compared the prevalence of the behavior within the study group to neighboring chimpanzee groups.
Main Results:
- Eight out of twelve chimpanzees in the study group adopted the "grass-in-ear" behavior.
- This peculiar behavior was observed only once in 82 individuals across three neighboring groups.
- The limited occurrence outside the main group suggests the behavior is not driven by ecological factors.
Conclusions:
- Chimpanzees exhibit a propensity for social learning and imitation, forming traditions.
- The "grass-in-ear" behavior serves as a case study for the spontaneous emergence of non-adaptive traditions.
- This highlights the role of social transmission in shaping chimpanzee behavior beyond immediate adaptive needs.
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