India, Oct. 13 -- Getting old is miserable. Your joints ache. Your eyes fail. Your hair grays and falls out. Wounds take longer to heal. Your risk of cancer creeps up each year. This happens to every mammal we know of from humans to dogs to mice to elephants.

Except for one that seems to have opted out of the process altogether.

The naked mole-rat looks like something that crawled out of a bad dream. It is a rodent that is wrinkled, nearly hairless, and armed with two oversized teeth used to dig tunnels. It lives underground in tightly packed colonies across East Africa, sealed off from the surface world. These creatures can survive without oxygen for nearly twenty minutes and often die not of disease, but from violent fights within the...