A study suggests similarities in age-related changes in stress response in chimpanzees and humans. Compared with other animals, humans have unusually long lifespans. In humans, aging affects the ability to regulate the stress response, but there is limited research on the effect of the stress hormone cortisol on other hominids. Between 1997 and 2017, Melissa Emery Thompson and colleagues examined age-related changes in urinary cortisol, a key product of the stress response, in 59 adult wild chimpanzees from Kibale National Park, Uganda. The authors also observed the chimpanzees' behaviors. Because age-related deterioration of the hypothalamic-pituitary-adrenal (HPA) axis leads to increased cortisol exposure, the authors tested the chimpanzees' urine for a blunted diurnal rhythm, increased average cortisol levels, and enhanced response to stressors--all of which are features of HPA aging in humans. Aging was associated with increased cortisol levels and blunting of the diurnal rhythm, which could not be explained by changes in social status. Males had approximately 33% higher urinary cortisol levels than females. Although males experienced their highest cortisol levels when exposed to sexually attractive females, this effect decreased with age. Conversely, females experienced their highest cortisol levels when they were sexually attractive, and this effect increased with age. The results suggest that the stress response ages similarly in chimpanzees and humans, according to the authors.
Article #19-20593: "Wild chimpanzees exhibit human-like aging of glucocorticoid regulation," by Melissa Emery Thompson et al.
MEDIA CONTACT: Melissa Emery Thompson, University of New Mexico, Albuquerque, NM; tel: 505-610-3860; email: memery@unm.edu
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Proceedings of the National Academy of Sciences