Ouroboros follows up on recent work on telomerase levels by size of species: "An outstanding question in the evolution of aging is whether telomerase activity (which preserves the ends of linear chromosomes and lengthens the replicative lifespan of cells) is related to lifespan per se. On on hand, it seems likely that it would be related positively: The longer one lives, the longer one's cells need to continue regenerating. On the other hand, the longer one lives, the more likely one is to accumulate [damaged, cancer-prone cells]. Since telomere maintenance is essential for tumor cell viability, one might not want these damaged cells to have ready access to telomerase expression ... and this logic might lead us to the opposite conclusion. ... Seluanov et al. show that among rodents, telomerase activity has co-evolved with body mass, but not lifespan. Furthermore, the correlation is negative: telomerase activity is more restricted in larger animals, perhaps as a defense against the increased cancer risk that comes from having more cells."