Identifying and understanding the processes that underlie the observed variation in lifespan within and among species remains one of the central areas of biological research. Questions directed at how, at what rate and why organisms grow old and die link disciplines such as evolutionary ecology to those of cell biology and gerontology. One process now thought to have a key role in ageing is the pattern of erosion of the protective ends of chromosomes, the telomeres. Here, we discuss what is currently known about the factors influencing telomere regulation, and how this relates to fundamental questions about the relationship between lifestyle and lifespan.