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.
This is a preview of subscription content,to check access.
Access this article
Similar content being viewed by others
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).
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.
Beckerman, S. (2016). Review of Huaorani transformations in twenty-first-century Ecuador: Treks into the future of time by Laura Rival. Hunter Gatherer Research, 2(4), 465–471.
Beckerman, S., Erickson, P., Yost, J., Regalado, J., Jaramillo, L., Sparks, C., Iriomenga, M., & Long, K. (2009). Life histories, blood revenge, and reproductive success among the Waorani of Ecuador. Proceedings of the National Academy of Sciences (USA), 106(20), 8134–8139.
Boehm, C. (1984). Blood revenge: The anthropology of feuding. Lawrence: University of Kansas Press.
Boster, J., Yost, J., & Peeke, C. (2004). Rage, revenge and religion: Honest signaling of aggression and nonaggression in Waorani coalitional violence. Ethos, 31(4), 471–494.
Cabodevilla, M. A. (1999). Los Huaorani en la historial de los pueblos del oriente. Coca: Cicame.
Cannon, W. (1929). Bodily changes in pain, hunger, fear, and rage. New York: Appleton-Century-Crofts.
Carré, J. M., & Olmstead, N. A. (2015). Social neuroendocrinology of human aggression: Examining the role of competition-induced testosterone dynamics. Neuroscience, 286, 171–186.
Carré, J. M., McCormack, C. M., & Hariri, A. R. (2011). The social neuroendocrinology of human aggression. Psychoneuroendocrinology, 36(7), 935–944.
Chacon, R. J., & Chacon, Y. (2019). Exploring warfare and violence from a cross-cultural perspective: Introduction to the special issue. Human Nature, 30, 145–148.
Chagnon, Napoleon. 2009. Interview: Napoleon A. Chagnon. Human Behavior and Evolution Society Newsletter (winter), 9–13. Available online at https://www.hbes.com/wp-content/uploads/2018/10/2009_Winter.pdf.
Crockford, C. C., Deschner, T., Ziegler, T. E., & Wittig, R. M. (2014). Endogenous peripheral oxytocin measures can give insight into the dynamics of social relationships: A review. Frontiers in Behavioral Neuroscience, 8, 1–14.
Davis, S. W. (1956). Stress in combat. Scientific American, 194(3), 31–35.
Davis, S. W., & Taylor, G. (1954). Stress in infantry combat. Tactics division infantry group technical memorandum ORO-T-295. Baltimore: Operations Research Office, Johns Hopkins University.
De Dreu, Carsten K. W., & Gross, J. (2018). Revisiting the form and function of conflict: Neurobiological and cultural mechanisms for attack and defense within and between groups. Behavioral and Brain Sciences., 1, 76. https://doi.org/10.1017/S0140525X18002170.
Dietrich, A., & McDaniel, W. F. (2004). Endocannabinoids and exercise. Journal of Sports Medicine, 38, 536–541.
Elias, M. (1981). Serum cortisol, testosterone, and testosterone-binding globulin responses to competitive fighting in human males. Aggressive Behavior, 7(3), 215–224.
Flinn, M. V., Ponzi, D., & Muchlenbein, M. (2012). Hormonal mechanisms for regulation of aggression in human coalitions. Human Nature, 23, 66–86.
Gardner, Robert. 1963. “Dead Birds.” Film directed by Robert Gardner, distributed by Documentary Educational Resources.
Gettler, L. T. (2014). Applying socioendocrinology to evolutionary models: Fatherhood and physiology. Evolutionary Anthropology, 23, 146–160.
Gilby, I. C., Brent, L. J., Wroblewski, E. E., Rudicell, R. S., Hahn, B. H., Goodall, J., & Pusey, A. E. (2013). Fitness benefits of coalitionary aggression in male chimpanzees. Behavioral Ecology and Sociobiology, 67(3), 373–381.
Grossman, D., & Christensen, L. (2008). On combat: The psychology and physiology of deadly conflict in war and peace (third ed.). Millstadt, IL: Warrior Science Publications.
Grossman, D., & Siddle, B. K. (1999). Psychological effects of combat. In Lester Kurtz and Jennifer Turpin (Eds.), Encyclopedia of Violence, Peace, and Conflict (Vol. 3, pp. 139–149). San Diego: Academic Press.
Hill, M. N., & Tasker, J. G. (2012). Endocannabinoid signaling, glucocorticoid-mediated negative feedback and regulation of the HPA axis. Neuroscience, 204, 5–16.
Jaeggi, A. V., Trumble, B., Kaplan, H., & Gurven, M. (2015). Salivary oxytocin increases concurrently with testosterone and time away from home among returning Tsimane’ hunters. Biological Letters, 11, 20150058.
Jansen, A. S. P., Van Nguyen, X., Karpitskiy, V., Mettenleiter, T. C., & Loewy, A. D. (1995). Central command neurons of the sympathetic nervous system: Basis of the fight-or flight response. Science, 270, 644–646.
Keeley, L. (1996). War before civilization. New York: Oxford University Press.
Kemeny, M. (2003). The psychobiology of stress. Current Directions in Psychological Science, 12(4), 124–129.
Levenson, R. W. (2003). Blood, sweat and fears: The autonomic architecture of emotion. Annals of the New York Academy of Sciences, 1000, 348–366.
Liening, S. H., & Josephs, R. A. (2010). It is not just about testosterone: Physiological mediators and moderators of testosterone’s behavioral effects. Social and Personality Psychology Compass, 4(11), 982–994.
Lu, F. (1999). Changes in subsistence patterns and resource use of the Huaorani Indians in the Ecuadorian Amazon. PhD dissertation, Curriculum in Ecology, University of North Carolina at Chapel Hill.
Macfarlan, S., Erickson, P., Yost, J., Regalado, J., Jaramillo, L., & Beckerman, S. (2018). Bands of brothers and in-laws: Waorani warfare, marriage and alliance formation. Proceedings of the Royal Society B, 285, 20181859.
Montoya, E. R., Terburg, D., Bos, P. A., & Van Honk, J. (2012). Testosterone, cortisol, and serotonin as key regulators of social aggression: A review and theoretical perspective. Motivation and Emotion, 36(1), 65–73.
Robarchek, C., & Robarchek, C. (1998). Waorani: The contexts of violence and war. Fort Worth: Harcourt Brace.
Romero, M. L., & Butler, L. K. (2007). Endocrinology of stress. International Journal of Comparative Psychology, 20(2), 89–95.
Samuni, L., Preis, A., Mundry, R., Deschner, T., Crockford, C., & Wittig, R. M. (2017). Oxytocin involvement during intergroup conflict in wild chimpanzees. Proceedings of the National Academy of Sciences, 114(2), 268–273.
Soares, M. C., Bshary, R., Fusani, L., Goymann, W., Hau, M., Hirschenhauser, K., & Oliveira, R. F. (2010). Hormonal mechanisms of cooperative behavior. Philosophical Transactions of the Royal Society B, 365(1553), 2737–2750.
Sutton, J. R., Coleman, M. J., Casey, J., & Lazarus, L. (1973). Androgen responses during physical exercise. British Medical Journal, 1, 520–522.
Van Anders, S., Goldey, K. L., & Kuo, P. X. (2011). The steroid/peptide theory of social bonds: Integrating testosterone and peptide responses for classifying social behavioral contexts. Psychoneuroendocrinology, 36, 1265–1275.
Wallis, E. (1973). Aucas downriver. New York: Hodder Stoughton.
Wood, R. W. (2004). Reinforcing aspects of androgens. Physiology and Behavior, 83(2), 279–289.
Wood, R. W. (2008). Anabolic-androgenic steroid dependence? Insights from animals and humans. Frontiers in Neuroendocrinology, 29(4), 490–506.
Wrangham, R. (2018). Two types of aggression in human evolution. Proceedings of the National Academy of Sciences (USA), 115(2), 245–253.
Yost, J. (1981). The Waorani. In G. Ligabue (Ed.), Ecuador in the shadow of the volcanoes (pp. 95–115). Venice: Centro Studi Richerche Ligabue Ediciones Libri mundi.
Zhang, Hejing, Jorg Gross, Carsten K. W. De Dreu, and Yina Ma. 2018. Oxytocin promotes coordinated out-group attack during intergroup conflict in humans. bioRxiv 403790. https://doi.org/10.1101/403790.
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.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Alarcon, R., Yost, J., Erickson, P. et al. The Proximate Causes of Waorani Warfare. Hum Nat 30, 247–271 (2019). https://doi.org/10.1007/s12110-019-09348-2