Department of Anthropology, University of Utah
April 16, 2016 19, Atrium Ballroom A/B
Female fertility ends at similar ages in chimpanzees (Pan troglodytes) and humans. Yet, unlike humans, chimpanzees suffer geriatric symptoms during their fertile years and usually die while still cycling—even in captivity. Such marked differences in general physiological senescence during the years preceding menopause imply differences in perimenopausal biology. Yet we know little of those differences, even though chimpanzees are favored models for the ancestral life history from which our distinctive post menopausal longevity evolved.
Here, we improve current characterizations of those differences by adding to quantitative indices of somatic aging in female chimpanzees across adulthood. Over three weeks, we trained seven female chimpanzees (ages 21-48) at the Yerkes National Primate Research Center to voluntarily and maximally squeeze a device engineered to measure grip strength in the species. All training and experimental sessions were completed using a positive reinforcement regimen.
Having compared our results to published values of these measures on women through the same ages, it is clear that chimpanzee females experience somatic aging at an accelerated rate than their human counterparts. Linear regression models demonstrate that the age-dependent slope in chimpanzees is steeper than evidenced in humans.
By directly addressing the interaction between somatic and reproductive aging, we aim to strengthen the foundation for describing and explaining life history similarities and differences between chimpanzees and humans. Results advance our understanding of the proximate mechanisms that influence age-dependent changes in chimpanzees, providing a crucial comparative standard for identifying distinctively evolved features of the perimenopausal experience in humans.
We were supported by the National Science Foundation, grant number BCS 0717886.