My research is focused on orangutan behavior and biology both as a way to further our understanding of endangered great apes and to provide clues to human evolutionary history. My Gunung Palung Orangutan Project gathers information on many aspects of orangutan ecology, social behavior, development, physiology, cognition, and ranging behavior. In particular, I have focused on the reproductive physiology of male and female orangutans with methods I developed for non-invasive monitoring of steroids through urine sampling. These studies, including nutritional analyses of orangutan foods, have elucidated the influence of food availability on the sensitive reproductive system of the orangutan and have provided clues to the enigmatic patterns of male growth and development. I am also actively involved with trying to protect this endangered species and their rain forest habitat through conservation activities, including education, public awareness, population and habitat censusing, and active interactions with Indonesia government organizations to fight illegal logging activities.