Do cooperatively breeding mammals live longer? A re-appraisal

Recent comparative studies have suggested that cooperative breeding is associated with increases in maximum lifespan among mammals, replicating a pattern also seen in birds and insects. In this study, I re-examine the case for increased lifespan in mammalian cooperative breeders by analysing a large dataset of maximum longevity records. Unlike one previous study, I found no consistent, strong evidence that cooperative breeders have longer lifespans than other mammals, after having controlled for variation in body mass, mode of life and data quality. The only exception to this general trend was displayed by the African mole-rats (the Bathyergid family): all members of this family are relatively long-lived, but the social, cooperatively breeding species appear to be much longer-lived than the solitary species, the latter having not been known to live beyond 11 years in captivity. However, solitary mole-rat species have rarely been kept in captivity or followed longitudinally in the wild, and so it seems likely that their maximum lifespan has been grossly underestimated when compared to the highly researched social species. As few other subterranean species have received much attention in a captive or wild setting, I also suggest that current data also makes it impossible to rule out a causal role of subterranean living on lifespan extension in mammals, and that any future studies wanting to test for such an association should wait until more high quality longevity data is available from a wider range of permanently subterranean species.