Haneul Jang

Humans have unique life history traits, including short interbirth interval, early age at weaning and extended childhood. To successfully raise multiple offspring, mothers receive support from others, defined as cooperative breeding, which has been considered as a key to the demographic success of humans. This project aims to identify women’s cooperative relationships– particularly in motherhood– and their effects on women’s fitness outcomes, from the network perspectives. Combining data from ethnography and interviews with BaYaka hunter-gatherers and Bandongo fisher-farmers in Congo Basin with social network analysis, I investigate how women shape cooperative networks through mixed reciprocity across domains and age-graded cooperation. I further compare social support networks of mothers between egalitarian hunter-gatherers and patrilineal fisher-farmers, and test how women’s positions in social networks impact their inclusive fitness. This will allow us to test theories in human behavior ecology that explain the mechanisms of human cooperation, including kin selection, homophily and reciprocity. Results from this study will provide insights into the socio-biological forces that drive cooperation in motherhood, as well as provide an ethological and ethnographic framework for understanding how women’s cooperation and social networks may have contributed to the demographic and ecological success of humans throughout evolutionary history.