The biological mechanisms at work during the aging process have long since intrigued and baffled scientists. Indeed, the very definition of aging continues to be the subject of much debate. The relationship between growing old and chronic disease is pivotal to the understanding of human longevity and the focus of many clinical studies. Dr. David Gems is a professor of biogerontology at the Institute of Healthy Aging, University College London. A leading voice in the quest to unravel the mysteries of aging, he works with tiny worms, called nematodes, to try to shed some light on the process. In this in-depth interview, David reveals why his theories about aging have shifted over the years. He argues that there in no central “underlying aging process” caused by damage or the body wearing out, as scientists once thought. The reality, he says, is “more complex and nuanced”.