The mole-rats of sub-Sarahan Africa are a taxon uniquely suited for examining hypotheses of social evolution. The Damaraland mole-rat, found in Kalahari red sands, displays an elaborate extended form of cooperative breeding. Here I review recent developments concerning the evolution of sociality in mole-rats, and discuss these in the light of current theories of the evolution of cooperative breeding. The central importance of the ecology of the Kalahari in shaping group size and group dynamics in the Damaraland mole-rat is emphasised.