TY - JOUR
T1 - Combat stress in a small-scale society suggests divergent evolutionary roots for posttraumatic stress disorder symptoms
AU - Zefferman, Matthew R.
AU - Mathew, Sarah
N1 - Funding Information:
Turkana interview survey questions were validated and administered with the help of Turkana fieldsite manager Gilbert Eweet Topos and research assistants Ekiru Alvos Calystus, Lilian Amuria Lotiira, Dis-mas Ekitoe Lomukuny, and James Muya Chegem. Interview questions and procedures were piloted primarily with the help of Ekiru Alvos Calystus. The Archaeology Section of the Earth Sciences Division of the National Museums of Kenya provided institutional support for research permits. American PCL-5 data were provided to us by the STRONG STAR Consortium and were collected with funding from Grants W81XWH-08-02-109 (Alan Peterson), W81XWH-08-02-0111 (Edna Foa), and W81XWH-08-02-0116 (Patricia Resick). Computational resources were provided by Albert Barreto and Camber Warren through the Naval Postgraduate School Coalition for Open-Source Defense Analysis Laboratory. We thank Katie Hinde, Devon Hinton, Bonnie Kaiser, Brandon Kohrt, Eric Meyer, Randy Nesse, Bilinda Straight, Ben Trumble, and Polly Wiesser for early discussions about this project; Emily Zefferman and anonymous reviewers for manuscript suggestions; and Richard McElreath and Bret Beheim for statistical advice. This research was funded by an Andrew Carnegie Fellowship (to S.M.) from the Carnegie Corporation of New York. Additional support was provided by a Donald R. Beall Defense Fellowship (to M.R.Z.) through the Naval Postgraduate School Foundation. The views in this paper are those of the authors and do not reflect official policy or positions of the Department of the Navy, Department of Defense, or the US Government. We especially thank the Turkana communities who hosted us during our research and the Turkana participants for agreeing to share their experiences with us.
Funding Information:
ACKNOWLEDGMENTS. Turkana interview survey questions were validated and administered with the help of Turkana fieldsite manager Gilbert Eweet Topos and research assistants Ekiru Alvos Calystus, Lilian Amuria Lotiira, Dis-mas Ekitoe Lomukuny, and James Muya Chegem. Interview questions and procedures were piloted primarily with the help of Ekiru Alvos Calystus. The Archaeology Section of the Earth Sciences Division of the National Museums of Kenya provided institutional support for research permits. American PCL-5 data were provided to us by the STRONG STAR Consortium and were collected with funding from Grants W81XWH-08-02-109 (Alan Peterson), W81XWH-08-02-0111 (Edna Foa), and W81XWH-08-02-0116 (Patricia Resick). Computational resources were provided by Albert Barreto and Camber Warren through the Naval Postgraduate School Coalition for Open-Source Defense Analysis Laboratory. We thank Katie Hinde, Devon Hinton, Bonnie Kaiser, Brandon Kohrt, Eric Meyer, Randy Nesse, Bilinda Straight, Ben Trumble, and Polly Wiesser for early discussions about this project; Emily Zefferman and anonymous reviewers for manuscript suggestions; and Richard McElreath and Bret Beheim for statistical advice. This research was funded by an Andrew Carnegie Fellowship (to S.M.) from the Carnegie Corporation of New York. Additional support was provided by a Donald R. Beall Defense Fellowship (to M.R.Z.) through the Naval Postgraduate School Foundation. The views in this paper are those of the authors and do not reflect official policy or positions of the Department of the Navy, Department of Defense, or the US Government. We especially thank the Turkana communities who hosted us during our research and the Turkana participants for agreeing to share their experiences with us.
Publisher Copyright:
© This open access article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND).
PY - 2021/4/13
Y1 - 2021/4/13
N2 - Military personnel in industrialized societies often develop posttraumatic stress disorder (PTSD) during combat. It is unclear whether combat-related PTSD is a universal evolutionary response to danger or a culture-specific syndrome of industrialized societies. We interviewed 218 Turkana pastoralist warriors in Kenya, who engage in lethal cattle raids, about their combat experiences and PTSD symptoms. Turkana in our sample had a high prevalence of PTSD symptoms, but Turkana with high symptom severity had lower prevalence of depression-like symptoms than American service members with high symptom severity. Symptoms that facilitate responding to danger were better predicted by combat exposure, whereas depressive symptoms were better predicted by exposure to combat-related moral violations. The findings suggest that some PTSD symptoms stem from an evolved response to danger, while depressive PTSD symptoms may be caused by culturally specific moral norm violations.
AB - Military personnel in industrialized societies often develop posttraumatic stress disorder (PTSD) during combat. It is unclear whether combat-related PTSD is a universal evolutionary response to danger or a culture-specific syndrome of industrialized societies. We interviewed 218 Turkana pastoralist warriors in Kenya, who engage in lethal cattle raids, about their combat experiences and PTSD symptoms. Turkana in our sample had a high prevalence of PTSD symptoms, but Turkana with high symptom severity had lower prevalence of depression-like symptoms than American service members with high symptom severity. Symptoms that facilitate responding to danger were better predicted by combat exposure, whereas depressive symptoms were better predicted by exposure to combat-related moral violations. The findings suggest that some PTSD symptoms stem from an evolved response to danger, while depressive PTSD symptoms may be caused by culturally specific moral norm violations.
KW - Combat stress
KW - Cross-cultural psychology
KW - Evolutionary medicine
KW - Moral injury
KW - PTSD
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U2 - 10.1073/pnas.2020430118
DO - 10.1073/pnas.2020430118
M3 - Article
C2 - 33876754
AN - SCOPUS:85104226550
SN - 0027-8424
VL - 118
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 15
M1 - e2020430118
ER -