The Highest Socially Organized Mammals

The Naked Mole Rat is the only other mammal known to exhibit eusocial behavior; a behavior that would otherwise be exclusive to ants, bees, wasps, termites, and sci-fi sequels from the 80s .

Heterocephalus glaber

A rodent which lives in colonies underground, digging with its enlarged front teeth. Only one female in a colony breed, and her offspring become workers or soldiers, helping dig the burrows in search of tubers underground. (bbc.com )

Also interesting in this species: they feel no pain!

The skin of naked mole rats lacks a key neurotransmitter called Substance P that is responsible in mammals for sending pain signals to the central nervous system. When naked mole rats are exposed to acid or capsaicin, they feel no pain. (wikipedia.org )