African mole-rats (family Bathyergidae) are subterraneanhystricomorph rodents occurring in a variety of habitats anddisplaying levels of sociality which range from solitary toeusocial, making them a unique mammalian taxonomic group totest ecological influences on sociality Here, we use anextensive DNA-based phylogeny and comparative analysis toinvestigate the relationship between ecology sociality andevolution within the family. Mitochondrial cytochrome-b and 12srRNA trees reveal that the solitary species are monophyleticwhen compared to the social species. The naked mole-rat(Heterocephalus glaber) is ancestral and divergent from theDamaraland mole-rat (Cryptomys damarensis), supporting previousfindings that have suggested the multiple evolution ofeusociality within the family. The Cryptomys genus is species-rich and contains taxa exhibiting different levels ofsociality, which can be divided into two distinct clades. A total of seven independent comparisons were generated withinthe phylogeny, and three ecological variables weresignificantly correlated with social group size: geophytedensity (p <0.05), mean months per year of rainfall greaterthan 25 mm (p < 0.001), and the coefficient of rainfallvariation (p = 0.001). These results support the food-aridityhypothesis for the evolution of highly social cooperativebehaviour in the Bathyergidae, and are consistent with thecurrent theoretical framework for skew theory.