Human Nature

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Prosocial Emotion, Adolescence, and Warfare

DNA Methylation Associates with Culturally Salient Combat Variables
  • Bilinda StraightEmail author
  • Belinda L. Needham
  • Georgiana Onicescu
  • Puntipa Wanitjirattikal
  • Todd Barkman
  • Cecilia Root
  • Jen Farman
  • Amy Naugle
  • Claudia Lalancette
  • Charles Olungah
  • Stephen Lekalgitele


Examining the costs and motivations of warfare is key to conundrums concerning the relevance of this troubling phenomenon to the evolution of social attachment and cooperation, particularly during adolescence and young adulthood—the developmental time period during which many participants are first recruited for warfare. The study focuses on Samburu, a pastoralist society of approximately 200,000 people occupying northern Kenya’s semi-arid and arid lands, asking what role the emotionally sensitized, peer-driven adolescent life stage may have played in the cultural and genetic coevolution of coalitional lethal aggression. Research in small-scale societies provides unparalleled opportunities for sharply defined variables, particularly in age generation societies in which all young men are initiated into “warriorhood.” Proposing an epigenetic and component behavior approach, we examine whether raiding activities such as number of raids, killing, and sparing enemy lives associate with DNA methylation in two candidate genes: MAOA, linked to mood and arousal, and NR3C1, linked to stress and immune response. We report statistically significant associations between the epigenetic variables and the combat (exposure) variables of overall raiding activity and reportedly showing mercy to enemies. In contrast, epigenetic variables did not associate with post-traumatic stress disorder (PTSD) symptom scores (a potential outcome measure), and the only combat variable associated with PTSD (but not DNA methylation) was losing one’s own livestock in a raid. These findings raise important questions concerning the mechanisms driving warfare’s paradoxical mix of violent and altruistic behaviors.


Warfare adolescence prosocial emotion cooperation epigenetics Kenya 



In Kenya, the authors would like to thank the Kenyan Ministry of Education for permission to conduct research, University of Nairobi and Laikipia University for affiliation and collegial interaction in Kenya, and the Samburu participants and their families for supporting and participating in the research. In the United States the authors are grateful to Western Michigan University Office of the Vice President for Research and College of Arts and Sciences for kind support of the research. Additional appreciation is extended to Richard and Yamilette Chacon for organizing the 2015 and 2017 Warfare, Environment, Social Inequality and Peace Studies (Pro-Socialty) (WESIPS) Conferences; to the participants for their incisive comments, especially Stephen Beckerman, Paul Valentine, and Charles Hilton; to Larry Schell for encouragement, and to anonymous reviewers of the manuscript whose excellent and constructive comments enhanced the final paper. Background research on Samburu warriors and coalitional gun violence was supported by National Science Foundation Senior Grant 0413431 (Jon Holtzman, co-PI), with additional support from National Science Foundation Senior Grant 1430860.

Author Contributions

BS conceived the study’s pre-DNA phase, conceived and designed the culturally specific instrumentation including combat screens, supervised and checked translations, carried out the ethnographic interviews. BN and BS conceived the DNA methylation study component. AN and BS scored and interpreted standard psychosocial instrumentation. BS, CR, and JF supervised Kenyan translators and administered questionnaires to participants. TB and BS extracted the DNA. CL performed the bisulfite conversion, PCR, and supervised mass spectrometry. GO and PW performed the statistical analyses. CO and SL provided field support. BS wrote the paper, and BN, GO, TB, AN, CR, JF, CO, and SL commented on drafts.

Compliance with ethical standards

Human Rights and Informed Consent

All procedures performed in studies involving human participants were in accordance with the ethical standards of the Western Michigan University Human Subjects Institutional Review Board and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all individual participants included in the study.

Supplementary material

12110_2019_9344_MOESM1_ESM.docx (46 kb)
ESM 1 (DOCX 45.8 kb)


  1. Abbink, G. J. (1999). Violence, ritual, and reproduction: Culture and context in Surma dueling. Ethnology, 38(3), 227–242.CrossRefGoogle Scholar
  2. Abbink, G. J. (2006). Of snakes and cattle: The dialectics of group esteem between Suri and Dizi in Southwest Ethiopia. In I. Strecker & J. Lydall (Eds.), Ethiopian images of self and other: Essays on cultural contact, respect and self-esteem in Southern Ethiopia (pp. 227–245). Münster: Lit Verlag.Google Scholar
  3. American Psychiatric Association. (2013). Diagnostic and Statistical Manual of Mental Disorders (5th ed.). Arlington, Washington, D.C.: American Psychiatric Publishing.CrossRefGoogle Scholar
  4. Anderson, D. M. (2002). Eroding the commons: The politics of ecology in Baringo, Kenya 1890s-1963. London: James Currey.Google Scholar
  5. Argentieri, M. A., Nagarajan, S., Seddighzadeh, B., Baccarelli, A. A., & Shields, A. E. (2017). Epigenetic pathways in human disease: The impact of DNA methylation on stress-related pathogenesis and current challenges in biomarker development. EBioMedicine, 18, 327–350.CrossRefGoogle Scholar
  6. Axelrod, R., & Hamilton, W. D. (1981). The evolution of cooperation. Science, 211(4489), 1390–1396.CrossRefGoogle Scholar
  7. Beckerman, S., Erickson, P. I., Yosts, J., Regalado, J., Jaramillo, L., Sparks, C., Iromenga, M., Long, K., & Linares, O. F. (2009). Life histories, blood revenge, and reproductive success among the Waorani of Ecuador. Proceedings of the National Academy of Sciences, 106(20), 8134–8139.CrossRefGoogle Scholar
  8. Blystad, A. (2005). Fertile mortal links: Reconsidering Barabaig violence. In V. Broch-Due (Ed.), Violence and belonging: The quest for identity in post-colonial Africa (pp. 112–130). London: Routledge.Google Scholar
  9. Bogin, B., & Smith, H. (1996). Evolution of the human life cycle. American Journal of Human Biology, 8, 703–716.CrossRefGoogle Scholar
  10. Bollig, M. (1990). Ethnic conflicts in north-west Kenya: Pokot-Turkana raiding, 1969-1984. Zeitschrift fur Ethnologie, 155, 73–90.Google Scholar
  11. Bollig, M., & Oesterle, M. (2008). “We turned our enemies into baboons”: Warfare, ritual and pastoral identity among the Pokot of northern Kenya. In M. Bollig, A. Rao, & M. Bock (Eds.), The practice of war: Production, reproduction and communication of armed violence (pp. 23–51). New York: Berghahn Books.Google Scholar
  12. Botdorf, M., Rosenbaum, G. M., Patrianakos, J., Steinberg, L., & Chein, J. M. (2016). Adolescent risk-taking is predicted by individual differences in cognitive control over emotional, but not non-emotional, response to conflict. Cognition and Emotion, 31(5), 972–979.CrossRefGoogle Scholar
  13. Buffone, A., & Poulin, M. (2014). Empathy, target distress, and neurohormone genes interact to predict aggression for others—even without provocation. Personality and Social Psychology Bulletin, 40(11), 1406–1422.CrossRefGoogle Scholar
  14. Buffone, A., Poulin, M., DeLury, S., Ministero, L., Morrisson, C., & Scalco, M. (2017). Don’t walk in her shoes! Different forms of perspective taking affect stress physiology. Journal of Experimental Social Psychology, 72(2017), 161–168.CrossRefGoogle Scholar
  15. Bustamante, A. C., Aiello, A. E., Galea, S., Ratanatharathorn, A., Noronha, C., Wildman, D. E., & Uddin, M. (2016). Glucocorticoid receptor DNA methylation, childhood maltreatment and major depression. Journal of Affective Disorders, 206, 181–188.CrossRefGoogle Scholar
  16. Casey, B. J., & Caudle, K. (2013). The teenage brain: Self control. Current Directions in Psychological Science, 22(2), 82–87.CrossRefGoogle Scholar
  17. Chagnon, N. A. (1988). Life histories, blood revenge, and warfare in a tribal population. Science 239(4843): 985-992.Google Scholar
  18. Decety, J. (2011). The neuroevolution of empathy. Annals of the New York Academy of Sciences, 1231, 35–45.Google Scholar
  19. De Waal, F. B. M. (2008). Putting the altruism back into altruism: The evolution of empathy. Annual Review of Psychology, 59, 279–300.CrossRefGoogle Scholar
  20. Ducci, F., & Goldman, D. (2012). The genetic basis of addictive disorders. The Psychiatric Clinics of North America, 35(2), 495–519.CrossRefGoogle Scholar
  21. Efstathopoulous, P., Andersson, F., Melas, P. A., Yang, L. L., Villaescusa, C., Rüegg, J., Ekström, T. J., Forsell, Y., Galanti, M. R., & Lavebratt, C. (2018). NR3C1 hypermethylation in depressed and bullied adolescents. Translational Psychiatry, 8, 121.CrossRefGoogle Scholar
  22. Farré, P., Jones, M. J., Meany, M. J., Emberly, E., Turecki, G., & Kobor, M. S. (2015). Concordant and discordant DNA methylation signatures of aging in human blood and brain. Epigenetics Chromatin, 8, 19.CrossRefGoogle Scholar
  23. Fatusi, A. O., & Hindin, M. J. (2010). Adolescents and youth in developing countries: Health and development issues in context. Journal of Adolescence, 33(4), 499–508.CrossRefGoogle Scholar
  24. Ferguson, B. (2013). Pinker’s list: Exaggerating prehistoric war mortality. In D. P. Fry (Ed.), War, peace, and human nature: The convergence of evolutionary and cultural views (pp. 112–131). Oxford: Oxford University Press.CrossRefGoogle Scholar
  25. Fleisher, M. (2000). Kuria cattle raiding. Ann Arbor: University of Michigan Press.CrossRefGoogle Scholar
  26. Fratkin, E. (1979). A comparison of the role of prophets in Samburu and Maasai warfare. In K. Fukui & D. Turton (Eds.), Warfare among East African herders. Osaka: National Museum of Ethnology.Google Scholar
  27. Frazzetto, G., Lorenzo, D., Carola, G. V., Prioietti, L., Sokolowska, E., Siracusano, A., Gross, C., & Troisi, A. (2007). Early trauma and increased risk for physical aggression during adulthood: The moderating role of MAOA genotype. PLoS One.
  28. Fry, D. P. (2013). War, peace, and human nature: The challenge of achieving scientific objectivity. In D. P. Fry (Ed.), War, peace, and human nature: The convergence of evolutionary and cultural views (pp. 1–21). Oxford: Oxford University Press.CrossRefGoogle Scholar
  29. Fry, D. P., & Söderberg, P. (2013). Lethal aggression in mobile forager bands and implications for the origins of war. Science, 2013(341), 270–272.CrossRefGoogle Scholar
  30. Fuentes, A. (2017). The creative spark: How imagination made humans exceptional. New York: Dutton.Google Scholar
  31. Fukui, K., & Turton, D. (Eds.). (1979). Warfare among East African herders. Osaka: Osaka National Museum of Ethnology.Google Scholar
  32. Galaty, J. (1991). Pastoral orbits and deadly jousts: Factors in Maasai expansion. In J. Galaty & P. Bonte (Eds.), Herders, warriors and traders: Pastoralism in Africa (pp. 171–198). Boulder, CO: Westview Press.Google Scholar
  33. Gat, A. (2000a). The human motivational complex: Evolutionary theory and the causes of hunter-gatherer fighting. Part I. Primary somatic and reproductive causes. Anthropological Quarterly, 73(1), 20–34.Google Scholar
  34. Gat, A. (2000b). The human motivational complex: Evolutionary theory and the causes of hunter-gatherer fighting. Part II. Proximate, subordinate, and derivative causes. Anthropological Quarterly, 73(2), 74–88.Google Scholar
  35. Gibbons, A. (2004). Tracking the evolutionary history of a “warrior” gene. Science., 304, 818.CrossRefGoogle Scholar
  36. Glowacki, L., & Wrangham, R. (2015). Warfare and reproductive success in a tribal population. Proceedings of the National Academy of Sciences, 112(2), 348–353.CrossRefGoogle Scholar
  37. Glowacki, L., Isakov, A., Wrangham, R. W., McDermott, R., Fowler, J. H., & Christakis, N. A. (2016). Formation of raiding parties for intergroup violence is mediated by social network structure. Proceedings of the National Academy of Sciences, 113(43), 12114–12119.CrossRefGoogle Scholar
  38. Greiner, C. (2012). Unexpected consequences: Wildlife conservation and territorial conflict in northern Kenya. Human Ecology, 40(3), 415–425.CrossRefGoogle Scholar
  39. Greiner, C. (2013). Guns, land, and votes: Cattle rustling and the politics of boundary (re)making in northern Kenya. African Affairs, 112(447), 216–237.CrossRefGoogle Scholar
  40. Gurven, M., Kaplan, H., & Gutierrez, M. (2006). How long does it take to become a proficient hunter? Implications for the evolution of the extended development and long life span. Journal of Human Evolution, 51, 454–470.CrossRefGoogle Scholar
  41. Hart, D., & Marmorstein, N. R. (2009). Neighborhoods and genes and everything in between: Understanding adolescent aggression in social and biological contexts. Development and Psychopathology, 21, 961–973.CrossRefGoogle Scholar
  42. Hawkes, K. (2014). Primate sociality to human cooperation: Why us and not them? Human Nature, 25, 28–48.CrossRefGoogle Scholar
  43. Heald, S. (2000). Tolerating the intolerable: Cattle raiding among the Kuria of Kenya. In G. Aijmer & J. Abbink (Eds.), Meanings of violence (pp. 101–121). Oxford: Berg.Google Scholar
  44. Ho, V., Ashbury, J. E., Taylor, S., Vanner, S., & King, W. D. (2016). Quantification of gene-specific methylation of DNMT3B and MTHFR using Sequenom EpiTYPER. Data in Brief, 6, 39–46.CrossRefGoogle Scholar
  45. Hodgson, D. (2001). Once intrepid warriors: Gender, ethnicity, and the cultural politics of Maasai development. Bloomington: Indiana University Press.Google Scholar
  46. Hoffman, D. (2011). Violence, just in time: War and work in contemporary West Africa. Cultural Anthropology, 26(1), 34–57.CrossRefGoogle Scholar
  47. Holtzman, J. (2009). Uncertain tastes: Memory, ambivalence, and the politics of eating in Samburu, northern Kenya. Berkeley: University of California Press.Google Scholar
  48. Hook, G. R. (2009). “Warrior genes” and the disease of being Māori. MAI Review 2. Available online at
  49. Hrdy, S. (1999). Mother Nature: A history of mothers, infants and natural selection. New York: Pantheon.Google Scholar
  50. Hrdy, S. (2009). Mothers and others: The evolutionary origins of mutual understanding. Cambridge: The Belknap Press of Harvard University Press.Google Scholar
  51. Hutchinson, S. (1996). Nuer dilemmas: Coping with money, war, and the state. Berkeley: University of California Press.Google Scholar
  52. Jablonka, E. (2009). Transgenerational epigenetic inheritance: Prevalence, mechanisms, and implications for the study of heredity and evolution. The Quarterly Review of Biology, 84(2), 131–176.CrossRefGoogle Scholar
  53. Kaplan, H., Hill, K., Lancaster, J., & Hurtado, A. M. (2000). A theory of human life history evolution: Diet, intelligence, and longevity. Evolutionary Anthropology, 9, 156–185.CrossRefGoogle Scholar
  54. Kleinman, A., & Good, B. (1985). Introduction: Culture and depression. In A. Kleinman & B. Good (Eds.), Culture and depression: Studies in the anthropology and cross-cultural psychiatry of affect disorder (pp. 1–32). Berkeley: University of California Press.Google Scholar
  55. Knighton, B. (2003). The state as raider among the Karamojon: ‘Where there are no guns, they use the threat of guns’. Journal of the International African Institute, 73(3), 427–455.CrossRefGoogle Scholar
  56. Koenen, K. C., Uddin, M., Chang, S.-C., Aiello, A. E., Wildman, D. E., Goldmann, E., & Galea, S. (2011). SLC6A4 Methylation modifies the effect of the number of traumatic events on risk for posttraumatic stress disorder. Depression and Anxiety, 28(8), 639–647.CrossRefGoogle Scholar
  57. Kuzawa, C., & Thayer, Z. M. (2011). Timescales of human adaptation: The role of epigenetic processes. Epigenomics, 3(2), 221–234.CrossRefGoogle Scholar
  58. Lea, R., & Chambers, G. (2007). Monoamine oxidase, addiction, and the “warrior” gene hypothesis. The New Zealand Medical Journal, 120(1250), 2441.Google Scholar
  59. Lesorogol, C. K. (2008). Contesting the commons: Privatizing pastoral lands in Kenya. Ann Arbor: University of Michigan Press.CrossRefGoogle Scholar
  60. Little, P. (1992). The elusive granary: Herder, farmer, and state in northern Kenya. Cambridge: Cambridge University Press.CrossRefGoogle Scholar
  61. Maciej, C., & Henrich, J. (2011). Culture-gene coevolution, norm-psychology and the emergence of human prosociality. Trends in Cognitive Sciences, 15(5), 218–226.CrossRefGoogle Scholar
  62. Marmone, G. (2017). Danser et chanter un système d’âge: Anthropologie musicale des Samburu (Kenya). Thèse présentée et soutenue publiquement le 15/12/2017 de l’Université Paris Nanterre.Google Scholar
  63. Mathew, S., & Boyd, R. (2011). Punishment sustains large-scale cooperation in prestate warfare. Proceedings of the National Academy of Sciences, 108(28), 11375–11380.CrossRefGoogle Scholar
  64. McCabe, T. (2004). Cattle brings us to our enemies: Turkana ecology, politics, and raiding in a disequilibrium system. Ann Arbor: University of Michigan Press.CrossRefGoogle Scholar
  65. Melas, P. A., Wei, Y., Wong, C. Y., Sjöholm, L. K., Åberg, E., Mill, J., Schalling, M., Forsell, Y., & Lavebratt, C. (2013). Genetic and epigenetic associations of MAOA and NR3C1 with depression and childhood adversities. International Journal of Neuropsychopharmacology, 16, 1513–1528.CrossRefGoogle Scholar
  66. Mendenhall, E., Yarris, K., & Kohrt, B. A. (2016). Utilization of standardized mental health assessments in anthropological research: Possibilities and pitfalls. Culture, Medicine & Psychiatry, 40, 726–745.CrossRefGoogle Scholar
  67. Meng, H., Murrelle, E. L., & Li, G. (2008). Identification of a small optimal subset of CpG sites as bio-markers from high-throughput DNA methylation profiles. BMC Bioinformatics, 9, 457.CrossRefGoogle Scholar
  68. Merriman, T., & Cameron, V. (2007). Risk-taking: Behind the warrior gene story. The New Zealand Medical Journal, 120(1250), 2440.Google Scholar
  69. Mirzeler, M., & Young, C. (2000). Pastoral politics in the northern periphery in Uganda: AK-47 as change agent. Journal of Modern African Studies, 38, 407–430.CrossRefGoogle Scholar
  70. Mulligan, C., D’Errico, N., Stees, J., & Hughes, D. (2012). Methylation changes at NR3C1 in newborns associate with maternal prenatal stress exposure and newborn birth weight. Epigenetics, 7-8, 853–857.CrossRefGoogle Scholar
  71. Nagy, C., & Turecki, G. (2015). Transgenerational epigenetic inheritance: An open discussion. Epigenomics, 7(5), 781–790.CrossRefGoogle Scholar
  72. Nori, M., Switzer, J., Crawford, A. (2005). Herding on the brink: Towards a global survey of pastoral communities and conflict. An occasional working paper from the IUCN (International Institute for Sustainable Development) Commission on Environmental, Economic, and Social Policy. Available online:
  73. Oberlander, T. F., Weinberg, J., Papsdorf, M., Grunau, R., Misri, S., & Devlin, A. M. (2008). Prenatal exposure to maternal depression, neonatal methylation of human glucocorticoid receptor gene (NR3C1) and infant cortisol stress responses. Epigenetics, 3(2), 1–9.CrossRefGoogle Scholar
  74. Pacchierotti, F., & Spano, M. (2015). Environmental impact on DNA methylation in the germline: State of the art and gaps of knowledge. Biomed Research International, 2015, 123484.CrossRefGoogle Scholar
  75. Palma-Gudiel, H., Córdova-Palomera, A., Leza, J. C., & Fañanás, L. (2015). Glucocorticoid receptor gene (NR3C1) methylation processes as mediators of early adversity in stress-related disorders causality: A critical review. Neuroscience and Biobehavioral Reviews, 55, 520–535.CrossRefGoogle Scholar
  76. Patton, G., Coffey, C., Cappa, C., Currie, D., Riley, L., Gore, F., Degenhardt, L., Richardson, D., Astone, N., O Sangowawa, A., Adesola, Mokdad, A., Ferguson, J. (2012). Health of the world’s adolescents: A synthesis of internationally comparable data. The Lancet 379: 1665-1675.Google Scholar
  77. Perroud, N., Rutembesa, E., Paoloni-Giacobino, A., Mutabaruka, J., Mutesa, L., Stenz, L., Malafosse, A., & Karege, F. (2014). The Tutsi genocide and transgenerational transmission of maternal stress: Epigenetics and biology of the HPA axis. The World Journal of Biological Psychiatry, 15(4), 334–345.CrossRefGoogle Scholar
  78. Pinker, S. (2011). The better angels of our nature: Why violence has declined. New York: Penguin.Google Scholar
  79. Ploughshares Monitor (2013). Armed conflicts report summary. Accessed March 6, 2018 at
  80. Poulin, M., Holman, E. A., & Buffone, A. (2012). The neurogenetics of nice: Receptor genes for oxytocin and vasopressin interact with threat to predict prosocial behavior. Psychological Science, 23(5), 1–7.CrossRefGoogle Scholar
  81. Powers, S. T., van Schaik, C. P., & Lehmann, L. (2016). How institutions shaped the last major evolutionary transition to large-scale human societies. Philosophical Transactions of the Royal Society B, 371, 20150098.CrossRefGoogle Scholar
  82. Roscoe, P. (2007). Intelligence, coalitional killing, and the antecedents of war. American Anthropologist, 109(3), 485–495.CrossRefGoogle Scholar
  83. Rusieki, J., Chen, L., Srikantan, V., Zhang, L., Yan, L., Polin, M. L., & Baccarelli, A. (2012). DNA methylation in repetitive elements and post-traumatic stress disorder: A case-control study of US military service members. Epigenomics, 4(1).
  84. Saitoti, T. O. (1986). The worlds of a Maasai warrior: An autobiography. Berkeley: University of California Press.Google Scholar
  85. Schechter, D. S., Moser, D. A., Paoloni-Giacobino, A., Stenz, L., Gex-Fabry, M., Aue, R., Adouan, W., Cordero, M. I., Suardi, F., Manini, A., Rossignol, A. S., Merminod, G., Ansermet, F., Dayer, A. G., & Serpa, S. R. (2015). Methylation of NR3C1 is related to maternal PTSD, parenting stress and maternal medial prefrontal cortical activity in response to child separation among mothers with histories of violence exposure. Frontiers in Psychology, 6, 690.CrossRefGoogle Scholar
  86. Schiele, M. A., Ziegler, C., Kollert, L., Katzorke, A., Schartner, C., Busch, Y., Gromer, D., Reif, A., Pauli, P., Deckert, J., Herrmann, M. J., & Domschke, K. (2018). Plasticity of functional MAOA gene methylation in acrophobia. International Journal of Neuropsychopharmacology, 21(9), 822–827.CrossRefGoogle Scholar
  87. Shumay, E., Logan, J., Volkow, N. D., & Fowler, J. S. (2012). Evidence that the methylation state of the Monoamine Oxidase A (MAOA) gene predicts brain activity of MAOA enzyme in healthy men. Epigenetics, 7(10), 1151–1160.Google Scholar
  88. Silk, J. B., & House, B. R. (2011). Evolutionary foundations of human prosocial sentiments. Proceedings of the National Academy of Sciences, 108(2), 10910–10917.CrossRefGoogle Scholar
  89. Smith, A. K., Conneely, K. N., Kilaru, V., Mercer, K. B., Weiss, T. E., Bradly, B., Tang, Y., Gillespie, C. F., Cubells, J. F., & Ressler, K. J. (2012). Differential immune system DNA methylation and cytokine regulation in post-traumatic stress disorder. American Journal of Medical Genetics, Part B: Neuropsychiatric Genetics, 156B(6), 700–708.CrossRefGoogle Scholar
  90. Somerville, L. H., Jones, R. M., Ruberry, E. J., Dyke, J. P., Glover, G., & Casey, B. J. (2013). The medial prefrontal cortex and the emergence of self-conscious emotion in adolescence. Psychological Science, 24(8), 1554–1562.CrossRefGoogle Scholar
  91. Spencer, P. (1988). The Maasai of Matapato: A study of rituals of rebellion. Manchester, UK: Manchester University Press.Google Scholar
  92. Steinberg, L. (2016). Commentary on the special issue on the “Adolescent brain: Redefining adolescence.” Neuroscience and Biobehavioral Reviews, 70, 343–346.Google Scholar
  93. Straight, B. (2007). Miracles and extraordinary experience in northern Kenya. Philadelphia: University of Pennsylvania Press.CrossRefGoogle Scholar
  94. Straight, B. (2009). Making sense of violence in the badlands of Kenya. Anthropology and Humanism, 34(1), 21–30.CrossRefGoogle Scholar
  95. Straight, B. (2017). Uniquely human: Cultural norms and private acts of mercy in the warzone. American Anthropologist, 119(3), 491–505.CrossRefGoogle Scholar
  96. Straight, B. (n.d). What do (pastoralist) women want? Warfare, cowardice, and sexuality in northern Kenya. In M. Hoehne, E. Gabbert, & J. Eidson (Eds.), Essays in honor of Gunther Schlee, in review. Oxford: Berghahn.Google Scholar
  97. Straight, B., Naugle, A., Farman, J, Root, C., Lekalgitele, S., Olungah, C. (n.d.a). Killing, mercy, and empathic emotions: The emotional lives of East African warriors. In W. Kiblinger (Ed.), Analyzing and learning from human conflict, in review. New York: Springer.Google Scholar
  98. Straight, B., Onicescu, G., Needham, B., Barkman, T., Naugle, A., Wanitjirattikal, P., Root, C., Farman, J., Olungah, C., Lekalgitele, S. (n.d.b). NR3C1 and MAOA DNA methylation in Samburu young men associate with disastrous suffering and coalitional gun violence. In preparation.Google Scholar
  99. Suchiman, H., Eka, D., Slieker, R. C., Kremer, D., Slagboom, P. E., Heijmans, B. T., & Tobi, E. W. (2015). Design, measurement and processing of region-specific DNA methylation assays: The mass spectometry-based method EpiTYPER. Frontiers in Genetics, 6, 287.CrossRefGoogle Scholar
  100. Teschendorff, A. E., Menon, U., Gentry-Maharaj, A., Ramus, S. J., & Gayther, S. A. (2009). An epigenetic signature in peripheral blood predicts active ovarian cancer. PLoS ONE, 4(12), e8274.CrossRefGoogle Scholar
  101. Tyrka, A. R., Parade, S. H., Welch, E. S., Ridout, K. K., Price, L. H., Marsit, C., Philip, N. S., & Carpenter, L. L. (2016). Methylation of the leukocyte glucocorticoid receptor gene promoter in adults: associations with early adversity and depressive, anxiety and substance-use disorders. Translational Psychiatry, 6(7), e848.CrossRefGoogle Scholar
  102. Uddin, M., Aiello, A. E., Wildman, D. E., Koenen, K. C., Pawelec, G., de los Santos, R., Goldmann, E., & Galea, S. (2010). Epigenetic and immune function profiles associated with posttraumatic stress disorder. Proceedings of the National Academy of Sciences., 107(20), 9470–9475.CrossRefGoogle Scholar
  103. Uddin, M., Galea, S., Chang, S.-C., Aiello, A. E., Wildman, D. E., de los Santos, R., & Koenen, K. C. (2011). Gene expression and methylation signatures of MAN2C1 are associated with PTSD. Disease Markers, 30(2-3), 111–121.CrossRefGoogle Scholar
  104. van der Knapp, L. J., Riese, H., Hudziak, J. J., Verbiest, M. M. P. J., Verhulst, F. C., Oldehinkel, A. J., & van 699 Oort, F. V. A. (2014). Glucocorticoid receptor gene (NR3C1) methylation following stressful events 700 between birth and adolescence: The TRAILS study. Translational Psychiatry, 4, e381.Google Scholar
  105. van Duijvenvoorde, A. C. K., Peters, S., Braams, B. R., & Crone, E. A. (2016). What motivates adolescents? Neural responses to rewards and their influence on adolescents’ risk taking, learning, and cognitive control. Neuroscience and Biobehavioral Reviews, 70, 135–147.CrossRefGoogle Scholar
  106. van Zuiden, M., Geuze, E., Hanneke, L. D. M., Willemen, E., Vermetten, M. M., Heijnen, C. J., & Annemieke, K. (2011). Pre-existing high glucocorticoid receptor number predicting development of posttraumatic stress symptoms after military deployment. The American Journal of Psychiatry, 168(1), 89–96.CrossRefGoogle Scholar
  107. Varley, K. E., Gertz, J., Bowling, K. M., Parker, S. L., Reddy, T. E., Pauli-Behn, F., Cross, M. K., Williams, B. A., Stamatoyoannopoulous, J. A., Crawford, G. E., Absher, D. M., Wold, B. J., & Myers, R. M. (2013). Dynamic DNA methylation across diverse human cell lines and tissues. Genome Research, 23(3), 555–567.CrossRefGoogle Scholar
  108. Vukojevic, V., Kolassa, I.-T., Fastenrath, M., Gschwind, L., Spalek, K., Milnik, A., Heck, A., Vogler, C., Wilker, S., Demougin, P., Peter, F., Atucha, E., Stetak, A., Roozendaal, B., Elbert, T., Papassotiropoulos, A., & de Quervain, D. J.-F. (2014). Epigenetic modification of the glucocorticoid receptor gene is linked to traumatic memory and post-traumatic stress disorder risk in genocide survivors. The Journal of Neuroscience, 34(31), 10274–10284.CrossRefGoogle Scholar
  109. Weathers, F.W., Blake, D.D., Schnurr, P.P., Kaloupek, D.G., Marx, B.P., Keane, T.M. (2013a). The Life Events Checklist for DSM-5 (LEC-5). Instrument available from the National Center for PTSD at
  110. Weathers, F.W., Litz, B.T., Keane, T.M., Palmieri, P.A., Marx, B.P., Schnurr, P.P. (2013b). The PTSD Checklist for DSM-5 (PCL-5). Instrument available from the National Center for PTSD at
  111. Whittle, P. M. (2010). Health, inequality and the politics of genes. The New Zealand Medical Journal, 123(1320), 4265.Google Scholar
  112. Wilhelm-Benartzi, C. S., Koestler, D. C., & Karagas, M. R. (2013). British Journal of Cancer, 109(6), 1394–1402.CrossRefGoogle Scholar
  113. Wrangham, R. W. (1999). Evolution of coalitionary killing. Yearbook of Physical Anthropology, 42, 1–30.CrossRefGoogle Scholar
  114. Wrangham, R. W., & Peterson, D. (1996). Demonic males: Apes and the origins of human violence. Boston: Hougton Mifflin.Google Scholar
  115. Yehuda, R., & Bierer, L. M. (2009). The relevance of epigenetics to PTSD: Implications for the DSM-V. Journal of Trauma Stress, 22(5), 427–434.CrossRefGoogle Scholar
  116. Yehuda, R., Daskalakis, N. P., Desarnaud, F., Makotkine, I., Lehrner, A. L., Koch, E., Flory, J. D., Buxbaum, J. D., Meaney, M. J., & Bierer, L. M. (2013). Epigenetic biomarkers as predictors and correlates of symptom improvement following psychotherapy in combat veterans with PTSD. Frontiers in Psychiatry, 4, 118.CrossRefGoogle Scholar
  117. Zannas, A. S., Provençal, N., & Binder, E. B. (2015). Epigenetics of posttraumatic stress disorder: Current evidence, challenges, and future directions. Biological Psychiatry, 78, 327–335.CrossRefGoogle Scholar
  118. Zefferman, M., & Mathew, S. (2015). An evolutionary theory of large-scale human warfare: Group-structured cultural selection. Evolutionary Anthropology, 24, 50–61.CrossRefGoogle Scholar
  119. Zhou, J., Sears, R. L., Xing, X., Zhang, B., Li, D., Rockweiler, N. B., Jang, H. S., Choudhary, M. N. K., Lee, H. J., Lowdon, R. F., Arand, J., Tabers, B., Gu, C. C., Cicero, T. J., & Wang, T. (2017). Tissue-specific DNA methylation is conserved across human, mouse, and rat, and driven by primary sequence conservation. BMC Genomics, 18, 724.CrossRefGoogle Scholar
  120. Ziegler, C., Richter, J., Mahr, M., Gajewska, A., Schiele, M. A., Gehrmann, A., Schmidt, B., Lesch, K.-P., Lang, T., Helbig-Lang, S., Pauli, P., Kircher, T., Reif, A., Reif, W., Vossbeck-Elsebusch, A. N., Arolt, V., Wittchen, H.-U., Hamm, A. O., Deckert, J., & Domschke, K. (2016). MAOA gene hypomethylation in panic disorder – Reversibility of an epigenetic risk pattern by psychotherapy. Translational Psychiatry, 6, e773.CrossRefGoogle Scholar
  121. Ziller, M. J., Gu, H., Müller, F., Donaghey, J., Tsai, L. T.-Y., Kohlbacher, O., De Jager, P. L., Rosen, E. D., Bennett, D. A., Bernstein, B. E., Gnirke, A., & Meissner, A. (2013). Charting a dynamic DNA methylation landscape of the human genome. Nature, 500(7463), 477–481.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  • Bilinda Straight
    • 1
    Email author
  • Belinda L. Needham
    • 2
  • Georgiana Onicescu
    • 3
  • Puntipa Wanitjirattikal
    • 3
  • Todd Barkman
    • 4
  • Cecilia Root
    • 1
  • Jen Farman
    • 1
  • Amy Naugle
    • 5
  • Claudia Lalancette
    • 6
  • Charles Olungah
    • 7
  • Stephen Lekalgitele
    • 8
  1. 1.Western Michigan University Department of AnthropologyKalamazooUSA
  2. 2.University of Michigan Department of EpidemiologyAnn ArborUSA
  3. 3.Western Michigan University Department of StatisticsKalamazooUSA
  4. 4.Western Michigan University Department of Biological SciencesKalamazooUSA
  5. 5.Western Michigan University Department of PsychologyKalamazooUSA
  6. 6.University of Michigan Epigenomics CoreAnn ArborUSA
  7. 7.University of Nairobi Institute of Anthropology, Gender & African StudiesNairobiKenya
  8. 8.Laikipia University Maralal Branch CampusMaralalKenya

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