The naked mole rat lives in underground colonies of seventy to eighty individuals. Among these individuals only one exceptionally large female rat, and only a few males, are sexually active. The other naked rats are sterile and have dedicated their entire lives to the digging of tunnels and the rearing and feeding of the reproducing nude rat's brood. (If I were to be a naked mole rat I'd sooner be one of the Queen's consorts rather than a mole rat nanny nun. But maybe that's just me. )