Kinship, marriage, and family systems in evolutionary perspective
Human kinship, marriage and family systems are uniquely complex among animals. Family structure and mating systems vary far more in our species than in any other, while still sharing strong commonalities with many species of mammals and birds. Marriage formalizes mating in a way that is unique to humans, and human kinship systems incorporate aspects of non-human kin structures along with great flexibility and cultural elaboration based in part on our unique ability to systematically recognize kin related through both mothers and fathers.
How such systems evolved, and especially what aspects of our physical or social environments influence their great historical and cross-cultural variation, has been an enduring question in both anthropology and evolutionary biology. Research in our lab seeks to both (a) illuminate the ecological predictors of cross-cultural patterns in kinship systems, marriage, and family composition, and (b) investigate behavioral variation within cultures, especially how kinship, marriage, and family patterns interact with fertility, investment in children, and the conditions under which family relationships are cooperative or competitive.
Previous research has examined changing marriage and parental investment strategies in South India, focusing on parental investment strategies in different social classes, the effects of kin on child outcomes, the causes of dowry inflation, the importance of paternal investment for status-related outcomes for older children and adults, and the functions of arranged marriage and consanguineous marriage. Recent collaborative work has emphasized the effects of ecology and kinship systems in predicting, or resolving, competition among kin, and the fit between subsistence patterns and marriage systems. Current work emphasizes the strategic motivations for the evolution of marriage payments (such as dowry and brideprice) and how these systems change over time, examining Indian weddings as costly signals, and analyzing the transition from brideprice to dowry in Bangladesh. Another collaborative project focuses on the evolutionary origins and ecological correlates of matriliny, a form of kinship which privileges ties through women. I am working with several colleagues on a related issue of Philosophical Transactions of the Royal Society B examining the ecological correlates of matriliny across mammals including a diversity of human societies.
Shenk 2007, Shenk & Mattison 2011, Shenk & Scelza 2012, Ellsworth et al. 2015, Chagnon et al. 2017, Scelza et al. 2019, Mattison et al. 2019, Shenk et al. 2019