Running head: AFFINAL CONFLICT 1 Mother-in-law daughter-in-law conflict: An evolutionary perspective, ethnographic review, and report of empirical data from the United States Jessica D. Ayers1, Jaimie Arona Krems2, Nicole Hess3, & Athena Aktipis1,4 1 Department of Psychology, Arizona State University 2 Oklahoma Center for Evolutionary Analysis (OCEAN), Department of Psychology, Oklahoma State University 3 Department of Anthropology, Washington State University 4Center for Evolution and Medicine, Arizona State University Corresponding author: Jessica D. Ayers,
[email protected], Department of Psychology, Arizona State University, Tempe, AZ 85287-1104, United States. Acknowledgments: We would like to thank Lee Cronk for his helpful comments on this manuscript. AFFINAL CONFLICT 2 Abstract Relationships with genetic relatives have been extensively studied in the evolutionary social sciences, but affinal relationships have received much less attention, and little work has examined both cooperation and conflict among affines from an evolutionary perspective. Yet humans have extensive interactions with the kin of their mates, i.e., in-laws or affines, as humans form long-term pair bonds with mates, with both sexes investing heavily in resulting offspring, thus leading to many opportunities for interacting with extended kinship networks. To contribute to the scholarship on affinal bonds, and particularly on perceptions of affinal conflict, we conducted an ethnographic review and collected empirical data on cooperation and conflict among affines. Here we present (1) a sample 37 of ethnographies showing cross-cultural evidence of conflict in affinal relationships. We also report (2) empirical evidence of self-reported cooperative and conflictual aspects in affinal relationships in a Western sample.