Ageing - not cancer, not heart disease - is the world’s leading cause of death and suffering. We accept as inevitable that as we get older our bodies and minds begin to deteriorate, and we are increasingly likely to be struck by dementia or disease. Ageing is so deeply ingrained in human experience that we never think to ask: is it necessary?    Biologists, on the other hand, have been investigating that question for years.    Ageless introduces us to the cutting-edge research that is paving the way for a revolution in medicine. It takes us inside the laboratories where scientists are studying every aspect of the body - DNA, mitochondria, stem cells, our immune systems, even longevity genes that have helped animals to a tenfold increase in lifespan - all in an effort to forestall or reverse our decline.    Computational biologist Andrew Steele explains what is happening as we age and practical ways we can help slow down the process. He reveals how understanding the scientific implications of ageing could lead to the greatest discovery in the history of medicine - one that has the potential to improve billions of lives, save trillions of dollars, and transform the human condition.