The Life Span of a Rodent May Aid Human Health

PROTECTED EXISTENCE
Naked mole rats like this one in South Africa rarely leave the safety of their underground tunnels. The queens never come to the surface. Even the workers are exposed only when they need to shovel out dirt.

By NICHOLAS WADE
NYT

They live in underground colonies with a queen, her harem of favorite males, soldiers to defend the tunnel system and workers to keep excavating in search of food. But despite having the social structure of an ants’ nest or beehive, naked mole rats are mammals about the size of a mouse. And among their many peculiarities are features that could, if understood, be of great relevance to human health and longevity.

Their life span is of extraordinary length for a rodent. Mice live a couple of years but mole rats can reach the venerable age of 28. The long life is probably a consequence of their protected existence. Mice have a short life span because they have many predators. Better to breed fast and young than prepare for an old age none will never live to see. Gray squirrels, on the other hand, have fewer enemies and can live for more than 20 years.

The naked mole rat lives an even more protected lifestyle than do squirrels. The queens never come to the surface. Even the workers are exposed only when they need to shovel dirt to the earth’s surface.

A colony’s principal danger is other mole rats who may break into the tunnel system, testing the soldier caste’s defenses. Another risk to life is a kind of civil war that breaks out when a queen dies. Other females, intimidated into staying barren while the queen lived, regain their fertility and fight until one emerges victorious. But casualties are generally low, and presumably because of this relative safety, mole rats have evolved the ability to live more than 10 times longer than mice.

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