Social organisation predicts lifespan in mammals

1. Recent comparative analyses have identified positive associations between social organisation and longevity in mammals, but independent replication with larger datasets is needed to establish the robustness of this pattern. 2. Here, we analysed maximum recorded lifespan, body mass, and social organisation data for 1,436 mammal species using Bayesian phylogenetic comparative methods, confirming that group-living and pair-living species exhibit longer lifespans than solitary species after controlling for body mass and phylogeny. 3. Pair-living species showed slightly longer lifespans than group-living species (though credible intervals overlapped), while body mass slopes did not differ substantially among social categories and activity period showed weak associations with lifespan. 4. These results provide independent corroboration of recent findings linking sociality to longevity in mammals and suggest that while group living may reduce predation risk, pathogen transmission costs in larger groups may constrain longevity benefits. 5. Our findings, based on the largest comparative dataset analysed to date, strengthen the evidence that social organisation is a key factor shaping mammalian life history evolution alongside body size and ecological adaptations.