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The Proximate Causes of Waorani Warfare

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In response to recent work on the nature of human aggression, and to shed light on the proximate, as opposed to ultimate, causes of tribal warfare, we present a record of events leading to a fatal Waorani raid on a family from another tribe, followed by a detailed first-person observation of the behavior of the raiders as they prepared themselves for war, and upon their return. We contrast this attack with other Waorani aggressions and speculate on evidence regarding their hormonal underpinnings. On-the-ground ethnographic observations are examined in light of the neuroendocrinological literature. The evidence suggests a chain of causality in launching lethal violence, beginning with a perceived injury, culminating in a massacre, and terminating in rejoicing. Although no blood or saliva samples were taken at the time of this raid, the behaviors were consistent with a deliberate initiation of the hormonal cascade characterizing the “fight-or-flight” response, along with other hormonal changes. We conclude with observations on the stratified interrelationships of the cognitive, social, emotional, and neuroendocrinological causes of aggression leading to coalitional male homicide.

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  1. This manuscript is part of the special issue of Human Nature on “Exploring Warfare and Violence from a Cross-Cultural Perspective: Selected Papers from the 2015 and 2017 WESIPS Conferences” (Chacon and Chacon 2019).

  2. Spears used in raiding are made from the chonta palm; it is believed that to drink chonta fruit beer after a raid invokes the fury of the raid and can incite a retaliatory raid.


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Many people have commented on this manuscript. We offer our thanks particularly to Helen Fisher, Rick Jacobs, Steve O’Neill, Dane Sawyer, Don Shule, Bilinda Straight, Ming Tien, Steve Wilson, and Ed Zuckerman, none of whom, of course, has any responsibility for any errors or omissions.

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Correspondence to Stephen Beckerman.

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Alarcon, R., Yost, J., Erickson, P. et al. The Proximate Causes of Waorani Warfare. Hum Nat 30, 247–271 (2019).

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