While Benjamin Franklin’s famous quote about death and taxes remains true for most, the same might not be said for some of the world’s billionaires. And their efforts to extend life are under way. Most recently, a Silicon Valley start-up called Altos Labs signed up a dream team of scientists, including numerous Nobel laureates, with an aim to rejuvenate human cells. Ian Sample speaks to Prof Janet Lord about the science of ageing, extending our health as well as our lifespans, and how old we could actually go. Help support our independent journalism at theguardian.com/sciencepod