Department of Anthropology
University of Nevada, Las Vegas
Hormones and Human Childcare: Evolutionary and Proximate Dimensions of a Cooperative Breeder
Friday, November 20, 2009
Lecture Hall 2, 4:00 PM
Unlike most mammals, humans breed in cooperative groups, obtaining care from fathers, grandmothers, older sisters, and others, in addition to mothers. Sarah Hrdy has refined this model of humans as cooperative breeders in her latest book, Mothers and Others. Here, we focus on the proximate hormonal mechanisms associated with human care of young children. To do that, we first touch on some basic conceptual foundations of behavioral endocrinology, highlight the importance of comparative research, and briefly survey the available human data on the subject. Hormones of pregnancy are thought to prime human maternal care, though direct evidence of this is surprisingly slim; instead, most research focuses on elevations in cortisol associated with attentive care to babies. Research on fathers indicates that male involvement in family life is commonly associated with lower testosterone, evidenced from samples of men such as the hunter-gatherer Hadza to men in Beijing and Boston. A few studies on fathers also implicate elevated prolactin and vasopressin levels. The lone study on grandmothers, conducted in Jamaica, found grandmothering associated with elevated vasopressin, but not oxytocin, prolactin, or cortisol levels. No data on the hormonal correlates of sibling or adoptive care are available, though three studies have implicated oxytocin in human-dog interactions, an interesting finding since dogs increasingly serve social functions as emotional surrogates of young children. We conclude with take home points, implications, and directions for future research in this young body of research.
Dr. Peter B. Gray is Assistant Professor of Anthropology at the University of Nevada, Las Vegas. After earning undergraduate degrees in Anthropology and Geography/Environmental Studies at UCLA, he received his Ph.D. in Biological Anthropology at Harvard. He spent two years as a postdoctoral fellow in Clinical Endocrinology, working with andrologist Dr. Shalender Bhasin. He joined the faculty at UNLV in 2005, where he teaches and engages in research on the evolution and endocrinology of human behavior. He has engaged in collaborative research investigating aspects of human hormones and family life in the U.S., Kenya, China, and, most recently, Jamaica. He has coedited (with Peter T. Ellison) Endocrinology of Social Relationships (2009: Harvard University Press), and coauthored (with Kermyt G. Anderson) Fathers: Evolution and Human Paternal Care (In press: Harvard University Press). Persuaded early in his academic career about the power of an evolutionary perspective, he ponders its application to most everything under the sun, including life on the Las Vegas Strip.