They look pretty vulnerable, but naked mole-rats are up there with tardigrades in terms of hardy animals. The wrinkly rodents are all but immune to cancer, they're long-lived, they don't feel much pain, and they can actually survive extended periods without oxygen by mimicking plants. Now, researchers at Calico Life Sciences have uncovered a new superpower: technically, naked mole-rats don't age, violating what was previously considered a fundamental biological law.

Naked mole-rats live far, far longer than biology says they should. Judging by their body size and the lifespans of related rodents, mole-rats would be expected to live about six years in captivity. And yet, they regularly survive to be over 30, and look pretty good (biologically speaking, anyway) for their advanced age.

In fact, the creatures are such an anomaly that the Calico researchers suspected they might break Gompertz's mortality law. This formula, proposed in 1825 by British mathematician Benjamin Gompertz, describes the exponential increase in an adult's risk of death as they age. It's been found to fairly accurately describe mammals once they reach sexual maturity, and in humans, it translates to a doubling of mortality every eight years or so after the age of 30.

To study whether naked mole-rats conform to the norm, the Calico team gathered more than 3,000 points of data on the creature's lifespan. They found that a substantial portion of the animals sampled hit their 30th birthday, and their mortality curve stayed relatively flat. Unlike all other mammals ever studied, their risk of death didn't increase with the years, leading the authors to declare "the naked mole-rat as a non-aging mammal."

"Our research demonstrates that naked mole-rats do not age in the same manner as other mammals, and in fact show little to no signs of aging, and their risk of death does not increase even at 25 times past their time to reproductive maturity," says Rochelle Buffenstein, Senior Principale Investigator on the study. "These findings reinforce our belief that naked mole rats are exceptional animals to study to further our understanding of the biological mechanisms of longevity."

While it would be nice if there was some way to translate that longevity to humans, there's probably not a whole lot we can really do with that information. Still, understanding the biological mechanisms behind aging could eventually help us take advantage of them. In the meantime, it's another reason to marvel at these amazing, some would say aesthetically challenged, little animals.

The research was published in the journal eLife.