Testing the bargaining vs. inclusive fitness models of suicidal behavior against the ethnographic record

Kristen Syme, Zachary Garfield, and Edward H. Hagen


Suicide is responsible for more deaths than all wars and homicides combined. Despite over a century of research on this puzzling and tragic behavior, and a recent increase in the number of treatments and intervention programs, it remains a global scourge. There is abundant research on suicidality in Western populations, but research on suicide among non-Western peoples is limited. Most notably, few studies analyze suicidality within small scale, non-industrial societies. Using ethnographic data from 53 cultures, this study tests two evolutionary theories of suicidal behavior: (1) deCatanzaro’s inclusive fitness model, which proposes that successful suicide would increase the inclusive fitness of individuals with low reproductive potential who are a burden on kin, and (2) the bargaining model, which proposes that suicide attempts are a costly signal of need, with completed suicides an unfortunate byproduct. These models were operationalized into two sets of variables, which were used to code 474 textual accounts of suicide extracted from the Probability Sample of the Human Relations Area Files. Results indicate limited support for the inclusive fitness model, which might apply primarily to older adults in harsh environments, and widespread support for most elements of the bargaining model, especially among younger healthy adolescents and adults.

Published in

Evolution and Human Behavior, vol. 37, n. 3, May 2016, pp. 179–192