Unlike in humans, the telomeres of long-lived bats do not appear to shrink with age.
A flying Myotis myotis bat. Image: Oliver Farcy
In 2005, scientists in Siberia captured a live Brandt’s bat, a species found across Europe and Asia, that was 41 years old. A house mouse, by comparison, is about twice as big, but might live to a ripe old age of two. “There’s nearly a law in nature,” Emma Teeling, a biology professor at University College Dublin, told me over the phone. “Small things live fast and die young. Big things live slow and live long,” like blue whales. “Bats really defy this.”
A bat. Video: Excerpt from "10 Things to Know About... Staying Young" Produced by New Decade TV Ltd, 2016 / GIF: Kate Lunau
Scientists don’t know why, and the mechanisms of aging are something of a mystery. Understanding why and how we age will be key to slowing down the aging process, even reversing it, if we can. Many researchers who study aging are focused on telomeres, found at the ends of our chromosomes, which tend to shrink as we grow older. This process could lead to age-related cell breakdown, tissue deterioration, and death, although the correlation between telomere length and aging isn’t perfect, and there’s still plenty to learn. (Telomeres are often compared to the protective plastic caps on the ends of shoelaces.)
In a remarkable new paper in Science Advances, Teeling and her team have performed the first-ever analysis of how telomere length changes over time in bats. Unlike in humans, the telomeres of Myotis bats, which are particularly long-lived, do not appear to shrink with age. Understanding why could one day help extend human longevity.
Teeling, a long-time bat researcher, has been fascinated by these creatures for years. “They don’t appear to experience age-related mortality,” she told me. “They die of things like starvation, or having an accident, or not having enough water.” More research is needed, but these bats aren’t known to get diseases of old age, she said—bats rarely, if ever, get cancer—and they also carry plenty of viruses, like Ebola and SARS, without getting infected. They tend to live a very long time, relative to their size. “Only 19 species of mammal are longer-lived than humans given their body size, and 18 of these species are bats,” says the new paper.
Bats are extremely tricky to study: They don’t tend to do well in a lab setting, and they’re hard to work with in the wild. So Teeling and her team, including lead author Nicole Foley (then a PhD student in Teeling’s lab), linked up with Bretagne Vivante, a grassroots environmental group in France that has been focused on local Myotis bats. In 2010, hundreds of these bats were microchipped as they left their roost so they could be tracked.
Teeling’s group went on to develop a method to non-lethally sample bats’ telomeres using wing punches, she told me. (Bats can regrow wing tissue.) Once they’d perfected this method, they got more researchers involved. The final study involved 10 research and conservation institutes, and bat biologists from across Europe and the UK. Altogether, researchers took wing biopsies from about 500 wild bats, from four species. The work represents more than 60 years of cumulative microcapture data of bats, she told me.
As with most mammals, two of the bat species did show telomeres that shortened as they got older. But in the longest-lived ones, the Myotis, telomeres didn’t shorten—this came as a complete surprise. The next question is how that’s possible, so scientists looked at these bats’ telomerase, an enzyme that lengthens telomeres. Telomerase is a huge focus of the anti-aging community, with some hawking unproven telomerase “supplements” to extend life. Yet this enzyme is also active in cancer cells. (Telomere shortening may have evolved in mammals in order to suppress cancer, the Science Advances paper says.)
Even weirder—scientists didn’t see telomerase expression in the Myotis bats, either. “These bats are somehow maintaining their telomeres without it,” Teeling told me. They looked at the genomes of 52 other mammals, focusing on 225 genes thought to be involved with maintaining telomere length, and identified two that could be responsible, called ATM and SETX. “It looks like these two genes have potentially evolved differently in bats than other mammals,” she told me. “This is a hypothesis. This is what we need to look at next.”
Video: Excerpt from "10 Things to Know About... Staying Young" Produced by New Decade TV Ltd, 2016 / GIF: Kate Lunau
I asked Teeling whether these genes could be good targets for future anti-aging drugs, if more research eventually backs up this theory. “I would say yes,” she said, cautioning that an “awful lot more steps” are needed before we get there. Really, this work is an entry point into understanding bat longevity—and eventually, maybe, our own.
Those bats whose telomeres do shorten, yet also manage to live a very long time, are also on Teeling’s mind. “In the longest-lived bats, telomere maintenance must play a role. But other bats live longer than expected, and their telomeres are shortening as you’d expect in other mammals,” she told me. “What have they evolved to allow them to [do] this?”
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