Who Won the U.S. Presidential Debate?

Adversity early in life can have permanent health consequences for people—even if their circumstances improve dramatically later on. Scientists use a cumulative adversity index, or CAI, which quantifies measures of hardship including poverty and stress, to understand health and longevity over the course of an individual's life. This has been helpful in identifying specific measures governments, health care providers and families can take to improve people's lives.

Wild animals may also experience adversity early in life, but the effect on their survival and longevity is unknown. While a similar tool could help scientists conserve animal populations by identifying the most influential stressors to mitigate, few populations have been studied over a long enough time to get the data needed to develop a CAI for that species.

UCLA biologists are changing that by creating the first cumulative adversity index for yellow-bellied marmots, based on 62 years of continuous data collection at the Rocky Mountain Biological Laboratory in Colorado. This is the second-longest study of individually marked mammals in the world.

The study, published in Ecology Letters, offers detailed steps for scientists with large datasets for other species to create their own CAI.

The index they developed identified some predictable but also surprising stressors with significant effects on marmot survival and longevity. For example, it was no surprise that a late start of the growing season reduced survival because marmots must gain weight during the summer for their seven- to eight-month hibernation. But the finding that summer drought had no effect was unexpected. Predation also played a smaller-than-anticipated role.

• Read More