But Finch cautions against overinterpreting the data. Because most animals were either killed or moved to other labs, fewer than 50 animals in the study lived past 15 years of age. (The oldest animal currently living in Buffenstein’s lab is 35.) More—and older—mole rats are needed to be sure that the risk of dying really is flat, Finch argues. But Buffenstein says the data simply do not show the typical aging pattern seen in mammals or any other animals. “If you look at any rodent aging study, 100 animals is all you need to see Gompertz aging,” she says. “Here we have 3000 data points and we’re not seeing it.”
It’s also possible that aging does happen, but much, much later than usual in mammals, Magalhaes points out. “I think it’s too early to say naked mole rats are nonaging animals,” he says. Indeed, the big mystery now is what happens in naked mole rats after 20 or 30 years, says Matthias Platzer, a biologist at the Leibniz Institute on Aging in Jena, Germany. “Maybe aging happens really fast then? Even Rochelle Buffenstein does not have the data on this.” But Platzer is happy that data on some of the world’s largest and oldest lab colonies of naked mole rats are now available.