Comparative biologist Rochelle Buffenstein has studied the animals for more than 30 years and has, quite literally, collected a lifetime’s worth of data. For each animal in her care, she recorded the date of birth and when it died, and whether it was killed for an experiment or given away to other researchers.
What she found was astonishing, says Buffenstein, who works at the longevity-focused Google biotech spinoff Calico in San Francisco, California: Naked mole rats seem to flout the Gompertz law, a mathematical equation that describes aging. In 1825, British mathematician Benjamin Gompertz found that the risk of dying rises exponentially with age; in humans, for instance, it doubles roughly every 8 years after the age of 30. The law applies to all mammals after adulthood, says João Pedro De Magalhães, a gerontologist at the University of Liverpool in the United Kingdom.
But Buffenstein did not see this trend in her lab animals. After they reached sexual maturity at 6 months of age, each naked mole rat’s daily chance of dying was a little more than one in 10,000. It stayed the same the rest of their lives and even went down a little, Buffenstein reports this week in elife. “To me this is the most exciting data I’ve ever gotten,” says Buffenstein. “It goes against everything we know in terms of mammalian biology.”
Studies have shown that naked mole rats have very active DNA repair and high levels of chaperones, proteins that help other proteins fold correctly. “I think the animals keep their house really neat and clean, rather than accumulate damage” that causes the physical deterioration associated with age, Buffenstein says.