Socially transmitted diffusion of a novel behavior from subordinate chimpanzees

Area of Science:

• Primate behavior
• Animal cognition
• Social learning

Background:

• Chimpanzees exhibit cultural diversity, but novel behaviors often fail to become traditions.
• A proposed "rank-bias" suggests limited diffusion of innovations due to copying dominant individuals.

Purpose of the Study:

• To investigate if subordinate chimpanzees can successfully initiate traditions of beneficial behaviors.
• To test the influence of demonstrator rank on the social transmission of novel actions.

Main Methods:

• Four captive chimpanzee groups were used, with either a high-rank (HR) or low-rank (LR) individual trained on a puzzle-box task.
• Models demonstrated the trained method, followed by group access to the puzzle-box for 8 hours.
• Network-based diffusion analysis (NBDA) assessed social transmission patterns.

Main Results:

• Chimpanzees in LR groups adopted the seeded method significantly more often than expected by chance.
• Individuals in LR groups used the seeded method on their first attempt more frequently than in HR groups.
• NBDA supported models where social transmission occurred primarily with subordinate demonstrators.

Conclusions:

• Chimpanzees are motivated to copy rewarding novel behaviors demonstrated by subordinates.
• Social transmission of innovations can be constrained by the rank of the demonstrator.
• Subordinate individuals can effectively seed traditions, even with cumulative innovation.