Scientists figure out how to accurately predict ages of wild animals using ‘epigenetic clock’

COLLEGE PARK, Md. — Precise aging of wild animals is now possible thanks to a pioneering study by scientists at the University of Maryland. Researchers say that DNA from “tiny” tissue samples can be used to accurately predict the age of bats in the wild.

Their study also shows that age-related changes to the DNA of long-lived species are different from those in short-lived ones.

The research team says their findings provide new insight into causes of age-related declines in species. It’s the first study to show that animals in the wild can be accurately aged using an epigenetic clock, which predicts age based on specific changes to DNA.

The findings also give new insight into possible mechanisms behind the exceptional longevity of many bat species.

Bat aging study
UMD-led study revealed age-related changes to the DNA of bats related to longevity. Clockwise from top left: common vampire bat, (G. Wilkinson), greater horseshoe bat, Rhinolophus ferrumequinum (G. Jones), velvety free-tailed bat, bat, (S. Puechmaille), and greater mouse-eared (M. Tschapka). All can live 30 years or longer except greater mouse-eared, which only lives to 6 years of age. (Credit: G. Wilkinson, G. Jones, S. Puechmaille, M. Tschapka)

“We hoped that these epigenetic changes would be predictive of age,” explains co-lead author Gerald Wilkinson, a UMD professor of biology, in a media release. “But now we have the data to show that instead of having to follow animals over their lifetime to be sure of their age, you can just go out and take a tiny sample of an individual in the wild and be able to know its age, which allows us to ask all kinds of questions we couldn’t before.”

The researchers looked at DNA from 712 bats of known age, representing 26 species, to “find changes in DNA methylation at sites in the genome known to be associated with aging.” They explain that DNA methylation is a process that switches genes off. It occurs throughout development and is an important regulator for cells. The process tends to decrease throughout the genome with increasing age.

Using machine learning to find patterns in the data, the researchers found that they could narrow a bat’s age to within a year based on changes in methylation at 160 sites in the genome. Species that tend to live much longer exhibit less change in methylation overall as they age than shorter-lived bats.

Study authors then analyzed the genomes of four bat species — three long-lived and one short-lived — to identify the specific genes present in those regions of the genome where age-related differences in methylation correlated with longevity.

They found specific sites on the genome where methylation was more likely to increase rather than decrease with age in the short-lived bats, but not in long-lived bats, and that those sites were located near 57 genes that mutate frequently in cancerous tumors and 195 genes involved in immunity. Wilkinson believes that analyzing methylation may provide insight into many age-related differences between species and lead to a better understanding of the causes of age-related decline across many species.

“Bats live a long time, and yet their hearing doesn’t decay with age, the way ours does,” he says. “You could use this method to see whether there are differences in methylation that are associated with hearing. There are all kinds of questions like this we can ask now.”

The study is published in the journal Nature Communications.

SWNS writer Stephen Beech contributed to this report.