Naked Mole-Rat Is Not Immortal But It Hardly Ages Even When Old

Going by its looks, the naked mole-rat isn’t much to write home about. But looks, as they say, can be deceptive, and this rodent may hold the secrets to alleviating the troubles that accompany the process of ageing among humans.

Weighing in at about 40 grams (about 1.4 ounces), the small mammal can live for over 30 years in captivity, which is about five times the lifespan for an animal that size. And it justifies the word "ripe" in the phrase "ripe old age" like no other animal. Menopause is absent among breeding females who can reproduce even past the age of 30. Neurogenesis and normal metabolism, heart functionality, body composition and bone quality continue well into old age, while chronic age-related diseases like cancer are extremely rare. They also don’t feel most kinds of pain, and when faced with low-oxygen conditions, behave similar to plants.

Scientists have been studying these unusual vertebrates to understand how they live the way they do. This area of research also involves Google’s parent company Alphabet, through one of its many projects, the secretive California Life Company, or Calico. It calls itself "a research and development company whose mission is to harness advanced technologies to increase our understanding of the biology that controls lifespan."

Calico researchers published a paper Thursday in the journal eLife where they said naked mole-rats don’t face a higher risk of dying as they grow older. That doesn’t mean that naked mole-rats don’t die, but that none of the factors that usually increase the chances of fatality among other animals — loss of regenerative abilities of the body’s cells, age-related diseases, and other physiological deterioration — affect them in any significant fashion.

The researchers collected over 3,000 data points from a large dataset that spanned over 35 years. They found both female and male naked mole-rats, whether they were reproductively active or not, displayed the same lack of increase of mortality risk. The reproductive status is important, because in each colony (there can be as many as 300 individuals in one colony), there is only one breeding female and three-four breeding males. The age of sexual maturity is an important factor among other mammals, when it comes to the increase in mortality hazards, but no so in the case of the naked mole-rat.

Dr. Rochelle Buffenstein, senior principal investigator at Calico, and one of the three authors of the paper, said in a statement: "Research has shown that the chance of dying for mammals such as humans, horses and mice, among others, increases exponentially with age, according to Gompertz’ law. 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. These findings reinforce our belief that naked mole rats are exceptional animals to study to further our understanding of the biological mechanisms of longevity."

The open-access paper is titled "Naked mole-rat mortality rates defy Gompertzian laws by not increasing with age" and it appeared online Jan. 24.