Cascading Behavior Among Chimpanzees
The existence of social learning among chimpanzees regarding using unique tools to help find food or to groom has been well documented. While these behaviors have an ecological basis in their origin, a 2014 study in Animal Cognition recorded a group of chimpanzees adapting a trend of putting a blade of grass in their ear. Researchers found that a Zambian chimpanzee named Julie started the trend in 2010 and the other members of her group began mimicking her behavior. Another interesting finding was that other neighboring groups of chimpanzees didn’t adopt the behavior. When I heard about other chimpanzees adopting Julie’s seemingly useless behavior, I thought of the course’s discussion on cascading behavior in networks.
Most of the in-class discussion and textbook revolved around human networks, so I thought it was very interesting how the same phenomenon could be observed among chimpanzees. It can be easily understood why other chimpanzees would copy a behavior that provides a tangible benefit to them (ex. easier to gather food or groom), and therefore these behaviors should have a lower threshold. However, Julie’s behavior has no additional benefit to survival, so it most likely had a higher threshold. Despite the presumably higher threshold, Julie’s behavior spread across her group. The articles do not mention a study of the social network within the group, but the theory outlined in the course would indicate that the network was organized in a manner where Julie’s behavior was easily transmitted to others. This may be explained as Julie’s position in the social hierarchy of the group made other chimpanzees more likely to adopt her behavior. Another explanation is that the chimpanzees exposed to Julie’s behavior had few “neighbors” in the social network, making them more likely to adopt a cascading behavior.
Source: http://www.smithsonianmag.com/smart-news/animal-fashion-some-chimps-are-putting-grass-ears-and-nobody-knows-why-180951888/?no-ist
https://www.thedodo.com/for-the-first-time-chimpanzees-605888880.html
http://link.springer.com/article/10.1007/s10071-014-0766-8