We should discuss the issue now, because we are close to delivering a true fountain of youth that could potentially extend our productive lifespan into our hundreds – it’s no longer the stuff of science fiction. ‘In just the last five years, there have been so many breakthroughs,’ says the Harvard geneticist David Sinclair. ‘There are now a number of compounds being tested in the lab that greatly slow down the ageing process and delay the onset of diabetes, cancer and heart disease.’

Sinclair, for instance, led a Harvard team that recently uncovered a chemical that reverses the ageing process in cells. The scientists fed mice NAD, a naturally occurring compound that enhances mitochondria – the cell’s energy factories – leading to a more efficient metabolism and less toxic waste. After just a week, tissue from older mice resembled that of six-month-old mice, an ‘amazingly rapid’ rate of reversal that astonished scientists. In human years, this would be like a 60-year-old converting to a 20-year-old practically before our eyes, delivering the tantalising dream of combining the maturity and wisdom of age with the robust vitality of youth. Researchers hope to launch human trials soon.