Beckman Fellow 2008-09

Rebecca Stumpf



Because chimpanzees are the closest living relative of humans, their sexual and social development provides a valuable comparative perspective for human adolescent development. Through her research with chimpanzees, Professor Stumpf plans to develop a plausible model for the maturation of our human ancestors; gain increased insight into human behavior; and identify possible selective pressures on hominin sexual maturation, and, consequently, human evolution.

The research project focuses on a developmental characteristic shared by chimpanzees and humans: males become fertile at the beginning of puberty, while females develop secondary sexual characteristics long before becoming fertile. It’s possible that among chimpanzee females this subfertile period allows them to (a) mature socially and sexually without the costs of pregnancy and/or (b) avoid inbreeding before they transfer into a new community. The proximate behavioral and hormonal mechanisms stimulating females to transfer are currently unknown. It’s especially important to understand this phenomenon because females, with their low reproductive output, are the limiting resource for changes in population size and thus the central element in population dynamics.

Professor Stumpf will conduct her research with the Kanyawara community of chimpanzees in the Kibale Forest of Uganda. This community currently consists of 10 adult males, 16 adult females, and 23 offspring. It has been studied since 1987, and long-term records are available. Stumpf will supplement these records with behavioral and hormonal data she will collect for 20 chimpanzees (age 5-19) over a three-year period.

Previously Professor Stumpf’s data-collection has been limited to summer breaks – a time when African habitats are drier, and the chimpanzees are more dispersed and less social. Now she can use the release time from her CAS appointment to collect data during the crucial periods of increased sociality among the chimpanzees.