Health Correlates of Extended Longevity in Captive Ring-Tailed Lemurs (Lemur catta).

Captive primates maintained at accredited institutions can live extraordinarily long lives and, as a result, are useful models for understanding the physiology of aging. Many institutions monitor primate health using serum chemistry panels and complete blood counts (CBCs), assays that capture organ and immune function and provide rich data for retrospective research. In this study, we compiled results from 169 serum chemistry panels and 168 CBCs collected between 2011 and 2022 at the Duke Lemur Center from 60 ring-tailed lemurs (Lemur catta), aged between 9 months and 32.8 years. Our dataset included 20 individuals who were 15 years or older, 10 of whom were 20 years or older. We found patterns consistent with gradual, age-related change in biomarkers associated with pancreas, kidney, and hepatobiliary function. Whereas concentrations of some markers increased with increasing age (e.g., amylase, lipase, gamma-glutamyl transferase, globulin, and total CO₂), concentrations of others decreased with increasing age (e.g., total bilirubin, calcium, and anion gap). We found significant age-by-sex interaction effects on blood urea nitrogen and cholesterol values, with females exhibiting sharper age-related increases in these analytes, particularly in late age, that could indicate steeper declines in kidney function than those experienced by males. Ultimately, our results capture a portrait of senescence(definition) in captive ring-tailed lemurs with extended longevity, with implications for the management of geriatric lemurs under human care. More broadly, including lemurs with diverse social systems and ecologies in retrospective studies of aging could illuminate physiological trends deeply rooted in the primate family tree and those uniquely shaped by evolution in Madagascar.