The Mashona mole-rat, Cryptomys darlingi, exhibits an extremereproductive division of labour. Reproduction in the colony isrestricted to a single breeding pair. The non-reproductive maleand female colony members are restrained from sexual activityby being familiar and related to one another and thereproductive animals.Circulating basal concentrations of luteinizing hormone (LH) aswell as LH levels measured in response to a single exogenousgonadotropin releasing hormone (GnRH) challenge are notsignificantly different between the reproductive and non-reproductive groups of either sex. Socially induced infertilityin both non-reproductive males and females does not result froma reduced pituitary secretion of LH or decreased sensitivity tohypothalamic GnRH, but rather appears to result from aninhibition of reproductive behaviour in these obligateoutbreeders.The African mole-rats exhibit a continuum of socially inducedinfertility with differing social species inhabiting regions ofvarying degrees of aridity. In this continuum a transition froma predominantly behavioural repression in a social mesic-adapted species through to complete physiological suppressionlacking incest avoidance in an arid-adapted eusocial speciesoccurs in this endemic African family of rodents.