Humans have always been obsessed with getting old, or rather staying young, but now science is beginning to catch up. Longevity has become a hot topic, from university laboratories to Silicon Valley startups. In the first of a Science Weekly three-part miniseries on ageing, Ian Sample speaks to Richard Faragher, a professor of biogerontology at the University of Brighton, to discover what we know about the biological hallmarks of ageing in our bodies –and why we have evolved to have the lifespans we do. Help support our independent journalism at theguardian.com/sciencepod