“You Can’t Sit With Us” – Hyenas and Triadic Closure
https://phys.org/news/2015-05-friends-friendseven-hyena.html
The article “It’s best to make friends of friends – even the spotted hyena knows that” reports on the nature of formation of social bonds between spotted hyenas. Taking more than 55,000 observations of the interactions between hyenas in Kenya over a period of 20 years, researchers from the National Institute for Mathematical and Biological Synthesis (NIMBioS) undertook one of the largest investigations of social network dynamics in a non-human species. In doing so, they found evidence among the hyena population of a common local structure that also exists in human social networks: the triad.
Just as human social behaviour demonstrates the triadic closure principle, in which two people who have a common friend are more likely to be friends themselves, so too does that of hyenas. In fact, triadic closure was found to be the most consistent factor influencing long-term patterns in the social structure of spotted hyenas. Similar to the way in which people engage in triadic closure in order to avoid unpleasantness or stress in specific relationships, hyenas, instead of forming alliances with all others in their large clans, cluster in triads. Doing so enables efficient cooperation and maximizes physical fitness of the individuals within the triad, hence increasing the likelihood of each individual’s survival in the wild. Interestingly, factors including the sex and social rank of the hyenas in the clan, as well as environmental factors such as abundance of prey, play a significant role in an individual’s decision regarding which triadic closure to form. This observation provides additional insight on how triadic closure occurs in the real world, adding depth to our class discussion on the theoretical aspects of the principle. Furthermore, the social behaviour of hyenas, which to some extent mirrors that of humans, seems to take the triadic closure principle to extremes as members of clans tend not to form relationships with any other member without an existing bond to a common individual. This is different from triadic closure in human relationships, in which the formation of a triad is simply one of many possibilities for forming social bonds, and an existing mutual friend is not a prerequisite for forming a new friendship. This could potentially lead to higher clustering coefficients in the social networks of hyenas compared to those of humans.
Based on the results of the study, it seems that the social behaviour of spotted hyenas is deliberate and clearly exemplifies the relevance of the triadic closure principle as it plays out in nature. Perhaps we could apply this to understanding human cooperation and sociality in greater depth, as well as to the social behaviour of other species.
very interesting study!