Research has shown that in some societies fathers have lower testosterone levels than non-fathers. Recent research by the investigators conducting this project was the first to use data collected over multiple years to show that it is the transition to married life and first-time fatherhood which causes large declines in testosterone, compared to if men remain single and childless. These decreases in testosterone in new fathers and married men have been hypothesized to improve men's functioning as parents and spouses, but this has yet to be thoroughly tested, and it is known that not all men who become married or have children experience substantial decreases in testosterone. This variation across men in their hormonal responses might be linked to differences in mens roles across professional, social, and familial (including nuclear and extended kin) lives. To clarify the behavioral effects of these hormonal changes, their variation across men, and how these hormonal aspects impact child well-being and relationship quality requires that men and their families be followed through time. This project will explore these questions among 908 men, their spouses, and children participating in a unique study in the Philippines that has followed a large sample of families for 30 years. Demographic, health, behavioral, and relationship data will be collected through interviews with men and their spouses. Parents will provide child well-being and development data, and men's testosterone will be measured in saliva samples.
By correlating hormone levels with detailed reports of men's familial, professional, and social behaviors and comparing with outcomes related to child well-being and family relationships, this study will help clarify the importance of men's biology to the functioning of families. This project also expands understanding of the ways in which behavior and biology differ between individuals and across cultural groups by contributing important insights into the range of human diversity in fathering/marital behaviors and their relationships to male hormonal profiles. In achieving these goals, the project will be central to an integrative graduate/undergraduate training program in human biology at Northwestern University, and will broadly and positively impact productive international scientific collaboration between scholars and universities in the United States and the Philippines.
