VN May 2021

Vetnuus | Mei 2021 6 Female baboons may not have bills to pay or deadlines to meet, but their lives are extremely challenging. They face food and water scarcity and must be constantly attuned to predators, illnesses and parasites, all while raising infants and maintaining their social status. A new study appearing April 21 in Science Advances shows that female baboons with high life-long levels of glucocorticoids, the hormones involved in the ‘fight or flight’ response, have a greater risk of dying than those with lower levels. Glucocorticoids are a group of hormones that help prepare the body for a challenge. While these hormones have many functions in the body, persistently high levels of glucocorticoids in the bloodstream can be a marker of stress. To understand the relationship between stress responses and survival, scientists studied 242 female baboons in Amboseli National Park, in Kenya. For more than 20 years, they measured glucocorticoid levels in the baboons’ faeces, a task that drew upon one of the world’s largest collections of data from a wild primate population. Females with higher levels of glucocorticoids in their faeces, either due to more frequent exposure to different types of challenges, or more intense stress responses, tended to die younger. The researchers then used these real values of hormone levels and risk of death to simulate a comparison between females that lived at opposite ends of the stress spectrum. Themodel showed that a hypothetical femalewhose glucocorticoid levels were kept very elevated would die 5.4 years sooner than a female whose glucocorticoid levels were kept very low. If they reach adulthood, female baboons have an expected lifespan of about 19 years, so 5.4-years represents a 25% shorter life. Five years more life can also represent enough time to raise one or two more infants. The team’s simulations represent extreme values that are unlikely to be maintained throughout the females’ lives, said Fernando Campos, an assistant professor at the University of Texas San Antonio and lead author of the study. Nonetheless, the link between exposure to stress-associated hormones and survival is clear. “Whether it’s due to your environment or your genes or something that we are not measuring, having more glucocorticoids shortens your life,” said Susan Alberts, a professor of biology and chair of evolutionary anthropology at Duke and senior author on the paper. The variation in glucocorticoid levels observed by Campos, Alberts, and their team shows that some females have it worse than others. Glucocorticoid levels may vary due to environmental factors, such Stress and death in female baboons —as measured by hormones in poop ByMarie Claire Chelini Photo: Bernard DuPont throughWikimedia Leading Article