The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

Season and aging affect the expression of a hormonal biomarker of life history in lemurs


1Department of Anthropology, University of North Carolina-Charlotte, 2Department of Anthropology, Emory University, 3Yerkes National Primate Research Center, Emory University

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The synthesis of the androgens DHEA and its sulfate DHEA-S in the adrenal is unique to primates. Age-related declines in circulating DHEA/DHEA-S observed in humans and some primates suggest that these androgens are biomarkers/regulators of life history, the rate of decline being proportional to variation in lifespan.

This study tested the generality of primate life history by comparing the age-specific patterning of sDHEA in diurnal lemurs. We predicted that longer lifespans and later reproduction would be associated with higher and more gradually declining sDHEA whereas seasonal breeding would magnify sDHEA. These predictions were tested in lemurs differing in reproductive onset and lifespan: Lemur catta, Eulemur mongoz, Propithecus coquereli, and Varecia variegata using serum samples obtained from the Duke Lemur Center. Forty-four samples from males 1-29 years of age were selected to match age and season (breeding [BS], nonbreeding [NBS]) of sampling in each species. Serum samples were analyzed for DHEA by radioimmunoassay.

MWW/ANOVA showed significant effects of season and species on sDHEA, with 3-fold higher sDHEA in the BS vs. NBS. DHEA levels gradually increased with age in Varecia, peaking in the oldest age-class, while those in Lemur and Propithecus rose markedly until peak fertility at age 12-15 years and then declined in a stepwise pattern thereafter. Eulemur exhibited variable age-related patterns of DHEA secretion.

The pattern of age-sDHEA interactions in lemurs is distinct from that observed in other primates and humans. These findings are important for the new contextual insights they provide into human life history and its architecture.

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