Bats may hold key to mammal longevity – including humans

When it comes to lifespan, researchers have found that four bat species have other animals beat. A team from the University of Maryland has worked to pinpoint two traits in the species that could offer up part of the secret to mammal longevity.

Their new study, published in the journal Biology Letters, found that common vampire bats, horseshoe bats, long-eared bats and one lineage of mouse-eared bats live up to four times as long as other mammals the same size. Among those four species, they found that a tolerance for variations in body temperature and differences in body size between males and females are signs that a species might be longer lived.

“This study provides multiple cases of closely related species with varying longevity, which gives us many opportunities to make comparisons and look for some underlying mechanism that would allow some species to live so long,” lead author Dr. Gerald Wilkinson said.

Mammal longevity is, in most cases, tied to body size. African elephants have an average lifespan of 70 years, and blue whales can live up to 90. Smaller mammals like mice live one to three years.

Humans are unusual, living about four times longer than other mammals the same size, and about twice as long as our closest primate relatives. Bonobos life about 40 years, and chimpanzees average 50 years.

The researchers believed that singling out unusually long-lived bat species could offer clues as to what traits go with that longevity.

The team analyzed a suite of traits, from hibernation, cave use, sex-based size differences, home range latitude, and tolerance for temperature changes.

They found that bats in extreme latitudes tend to live longer than those that lived near the equator. Those at more extreme locations – especially hibernators – tended to see their body temperatures rise and fall.

“Of the lineages of bats that live a long time, three of them are hibernators and one of them is the vampire bat,” Wilkinson said. “The vampire bat is very unusual for a mammal in that it can let its body temperature rise and fall throughout the day.”

Variations in body temperature could help mammals fight infections and preserve energy, the scientists theorized – similar to how humans’ fevers are a mechanism to fight infection.

Additionally, species where males and females were close to the same size tended to live longer than those in which the males were much longer.

The researchers are hoping to continue looking into exactly how those traits came to be linked with mammal longevity, and whether than can be used to increase our own lifespans.

“If we lived as long as bats, adjusted for size, we could live 240 years,” Wilkinson said. “Everybody wants to know how these animals can live so long. This kind of work can help us get to the answers.”

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By Kyla Cathey, Earth.com staff writer