Introduction

The eusocial naked mole-rat, Heterocephalus glaber, provides the most extreme mammalian example of social regulation of reproduction. One large, dominant female (the “queen”: Jarvis 1981), controls the reproduction of all males and females in a colony that may contain hundreds of individuals. Even though these small (20–80 g), highly specialized fossorial rodents live up to 18 years in captivity, in the wild most stand no chance of reproducing in their lifetime, because there is little opportunity to attain queen or consort status or to disperse from their natal colony (Brett, 1991a; Sherman, Jarvis, & Braude, 1992; Jarvis et al., 1994). As Sherman and colleagues discuss in this volume, the naked mole-rat is the mammalian equivalent of a eusocial insect such as the termites or wasps.

The naked mole-rat exhibits the classical characteristics of eusociality (Michener 1969; Wilson 1975). Colonies contain overlapping generations, and there is a clear division of reproductive labor in which only a few individuals produce offspring, while infertile group members cooperate in rearing offspring and protecting and servicing the colony (Jarvis 1981, 1991; Faulkes et al. 1991; Lacey & Sherman 1991). Naked mole-rats live in a closed society, where their subterranean habitat, eusociality, and extreme specializations to a fossorial life style (e.g., degenerate vision and poikilothermy), and xenophobic aggression to conspecifics from surrounding colonies lead to an apparent lack of dispersal and consequently to high levels of inbreeding (Buffenstein & Yahav 1991; Jarvis & Bennett 1991; Sherman et al. 1992; Jarvis et al. 1994).