Formation of raiding parties for intergroup violence is mediated by social network structure

Luke Glowacki, Alexander Isakov, Richard W. Wrangham, Rose McDermott, James H. Fowler, Nicholas A. Christakis

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


Intergroup violence is common among humans worldwide. To assess how within-group social dynamics contribute to risky, betweengroup conflict, we conducted a 3-y longitudinal study of the formation of raiding parties among the Nyangatom, a group of East African nomadic pastoralists currently engaged in small-scale warfare. We also mapped the social network structure of potential male raiders. Here, we show that the initiation of raids depends on the presence of specific leaders who tend to participate in many raids, to have more friends, and to occupy more central positions in the network. However, despite the different structural position of raid leaders, raid participants are recruited from the whole population, not just from the direct friends of leaders. An individual's decision to participate in a raid is strongly associated with the individual's social network position in relation to other participants. Moreover, nonleaders have a larger total impact on raid participation than leaders, despite leaders' greater connectivity. Thus, we find that leaders matter more for raid initiation than participant mobilization. Social networks may play a role in supporting risky collective action, amplify the emergence of raiding parties, and hence facilitate intergroup violence in small-scale societies.

Original languageEnglish (US)
Pages (from-to)12114-12119
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number43
StatePublished - Oct 25 2016

All Science Journal Classification (ASJC) codes

  • General


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