Doctoral Dissertation Research: Aging, frailty, and foraging ability in wild male primates

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

While longevity is often described as a uniquely human trait, other apes like chimpanzees also have extended lifespans, living twice as long as monkeys or lemurs. However, we don't fully understand the effects of aging on apes in the wild or which aspects of human longevity are unique. This doctoral research project will investigate how wild male chimpanzees age physiologically and behaviorally with a focus on how aging impacts foraging ability, which may reveal how frailty impacts fitness. The findings will help clarify whether chimpanzees' feeding behavior and performance change with age, and whether foraging could play an important role in shaping their patterns of senescence. This research will fill gaps in our knowledge on the senescence of male primate skeletal biology and may help to clarify whether fertility maintained late in life contributes to the evolution of extended lifespan. The investigators will engage in educational activities in the United States and near the research site in rural Uganda, and foster international research collaborations and capacity building. In addition, the continued presence of researchers in Kibale National Park helps protect one of the last tropical rainforests in all of East Africa, which is notably one of the principal strongholds of chimpanzees in this area. The proposed research will investigate aging in male chimpanzees living in an exceptionally large community at Ngogo, Kibale National Park, Uganda. The investigators will assess the physiological traits of adult male chimpanzees at various ages to assess how bone density, body mass, chewing ability, and energetic status may decrease in old age. To this end, the research will non-invasively collect and analyze fecal samples to assess chewing efficiency as well as urine samples to measure insulin biomarkers (an indicator of energetic status) and collagen biomarkers to investigate decreases in bone density. Behavioral observations will also be carried out to assess how these physical changes may impact movement, food selection, ingestion rates, mating effort, and sociality. Through a systematic study of aging male chimpanzees' physiology and behavior, this research aims to elucidate the processes of aging and its impact on fitness in wild animals. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.