Monkey See, Monkey Do
In 2010, experts studying Zambian chimpanzees observed something truly extraordinary; after one member of the chimpanzee group, Julie, stuck a piece of grass behind her ear, 8 out 12 members of her group followed suit. This phenomenon not only confirmed chimpanzees’ copycat behavior, but also confirmed them as cultural beings.
Julie, a female Zambian chimpanzee residing in Zambia’s Chimfunshi Wildlife Orphanage sanctuary, started this ‘primate fashion statement’ one day by nonsensically sticking a stiff, straw-like blade of grass in one or two of her ears. Over subsequent visits, Julie displayed this same behavior. Interestingly enough, over that same span, eight other chimpanzees followed, including her son Jack and other chimpanzees with who she interacted with – Kathy, Val and Miracle.
In four other Zambian chimpanzee groups living in the same Orphanage, experts did not observe the same trend. So what ignited this fashion trend in Julie’s group? This can most likely be explained by two network effects – the threshold cascade model and the centralization of nodes. For the most part, individuals wear things that are more generally popular, because it legitimizes the quality of the product. So for two people choosing what product to adopt, the payoff for both would be positive, as that would increase the number of people wearing the product. The more people that you are connected to appreciate the product, the more valuable that product becomes to. After Julie started placing the blade of grass behind her ear, Julie’s son Jack started to, too, probably because Jack had few other neighbors besides his mom. From there, the network grew – each of Julie’s neighbors who probably had few other neighbors adopted the same trend as Julie. This effect is most significant in small, dense clusters where nodes are highly interconnected but not connected to nodes outside of that cluster.
This phenomenon is especially true if the people that approve of the product are generally well-liked and influential. Again, this can be explained by the centralization of nodes. In humans, popular fashion trends follow the trends of celebrities, political leaders or other famous people. Powerful, well-known individuals create ripple effects among the general population when they decide to adopt a certain piece of clothing or aesthetic. When Kanye decides to wear big shirts and skinny jeans at a concert, millions follow. The connectedness of certain nodes directly determines how influential those nodes are in starting trends. In this social media era, where one tweet can be read by tens of millions of people, well-connected nodes are more powerful than ever in influencing trends. So why did Julie’s pack overwhelmingly decide to adopt the “grass-in-ear” trend? Most likely because Julie was a well-connected node in a highly centralized cluster. While other chimpanzees may have had one or two neighbors at most, Julie may have had more than all others.
Network effects can explain lots of human behavior. But is it uniquely human?
Sources: http://www.telegraph.co.uk/news/earth/wildlife/10945821/Chimps-develop-bizarre-trend-of-sticking-grass-in-ear.html