UCLA

Friendship is prevalent in human societies. Friendships are often formed among genetically unrelated individuals, who are willing to help each other in times of need, without careful accounting of benefits given to and received from each other. Evolutionarily, altruistic behavior among nonrelatives is inherently risky. This raises a question: how is altruism maintained among unrelated friends? The goal of my dissertation is to shed light on the form and function of human friendship from an evolutionary perspective. In my dissertation, I evaluated the role of reciprocity among friends, the contribution of friendship to an individual's social support, and the ways in which people keep track of favors given to and received from friends and others. Most ethnographic studies of friendship lack the systematic design to parse out different motives and behaviors, and most of the carefully controlled studies have been conducted in the US and Europe (often with college students), which may not be representative of a wider range of cultures. To address these gaps, I chose a less well-studied area in a non-western society as my field site, and conducted ethnographic studies in a Tibetan village, Gashari, in Huangnan Tibetan Autonomous Prefecture in Qinghai province in China. I applied both qualitative and quantitative research methods in my fieldwork, including surveys, network analysis, semi-structured interviews, and participant observations. By working in a different ecology, where non-kin friendships are embedded in networks of kinship, and applying systematic approaches that enable me to compare friendships in this Tibetan village with friendships in western societies, my dissertation has important implications on the evolutionary processes and proximate psychology that shape human friendship.