Although I have never carried a physical spear in my life, conflict is a common theme in the history of humanity and our daily lives. Our goal today is to understand a bit more about the formation of the green team and the red team in the below image, or more formally, why individuals choose to join a conflict.

Image of a raid from Wikipedia (https://en.wikipedia.org/wiki/Fenian)

The subject of our paper today is the Nyangatom, a group of East African nomadic pastoralists that are currently engaged in small-scale warfare. The primary type of intergroup conflicts for the Nyangatom is the raid, in which a small group of men, “a raiding party”, try to seize livestock from nearby groups, kill enemies and escape unharmed. Different from the complicated factors in forming an army in a war, these raids are spontaneous violent activities, which resemble settings such as terrorist groups.

The formation of such a raiding party is contingent on individual decisions of whether to join the conflict. If we make an analogy between deciding to join a conflict and being infected by a virus, the process of forming a party is analogous to the diffusion of a virus among people. (Learn more about diffusion in networks.)

The focus of this paper is to understand the role of social structure in self-organized collective violence. The researchers conducted extensive semistructured interviews to collect this valuable dataset and used gift allocation tasks to determine a snapshot of the social network among the Nyangatom.

Among a large set of interesting analyses in this paper, here are some personal highlights:

Personal characteristics of individuals could not predict their decisions to join raids.

Leaders joined more raids and were more connected than anyone else.

Leaders may be able to mobilize their direct friendship contacts to join raids, but are no more capable than anyone else in the population to mobilize their friends.

Neither did leaders have more effect per person, nor did they have a greater total effect.

Kinship did not motivate individuals to join a raid (siblings did not matter).

One picture from the paper

The red bar and blue bar to the left suggests that direct nonleader friends are more motivating than leaders. The negative coefficients when the social distance is larger than suggest that people outside a person’s immediate connections demotivate participation. In other words, the “virus” does not go far in the diffusion analogy above.

One sentence summary

[L]eadership matters in initiating collective violence in this small-scale society, but that it is not an especially important factor with respect to who joins the raiding parties.

Final bit of thoughts

Networks are ubiquitous, even in conflicts. Networks are also in constant flux, especially in conflicts. It is unclear how these findings based on the Nyangatom are generalized in different settings. The static social network used in this paper leaves many open questions. However, a better understanding of how networks arise and evolve around conflicts may shed light on how to deal with conflicts.

Paper link: http://www.pnas.org/content/113/43/12114.short