Ecology and endocrinology of aggression in chimpanzees. Richard Wrangham
This study will investigate how aggression among wild chimpanzees is related to age, sex, endocrine status and seasonal variation in energy availability. From 2004 to 2009 the research team will compile a daily record of chimpanzee behavior and ecology within the Kanyawara community of Kibale National Park. The Kanyawara community is a social group of 50 chimpanzees that Wrangham has monitored since 1988, and that are well habituated to the presence of humans. In addition to systematically recording a wide range of behaviors, the research team will also collect urine samples at a rate of about 100 per month. A total of about 11000 urine samples will be available from 1997 to 2009. The concentrations of testosterone, cortisol, progesterone and estradiol will be assayed in these samples. The researchers will test hypotheses about the relationship of steroid production to behavior (e.g. intergroup aggression, hunting, or status competition), and to behavioral contexts (e.g. mating competition for attractive vs. less attractive females). To do so, they will create a relational database and data management system. This will permit investigations of questions about relatively long-term, infrequent, and complexly related processes in chimpanzee behavioral biology. Long-term questions include how male endocrine status changes with dominance rank, how the frequency of aggression changes with age, or how and why female core areas shift or remain stable over time. Questions about infrequent events include how testosterone output is related to mate-guarding, to border patrols, or to hunting. Complexly related processes include relationships among behavior, party composition, and location. In sum, this research will provide information on a wide range of chimpanzee behaviors, including reproductive strategies, life-histories and social relationships, and will seek to understand them in terms of local ecology and in comparison to other populations.
