As scientists uncover the secrets of aging, prolonging life is looking more possible than ever. But does extending our years indefinitely come with too many downsides? Overpopulation, inequality and a world where the old never retire are just some concerns. Meanwhile, research shows our mental abilities and creativity peak young. With power concentrated among the elderly, what kind of stagnant society might we create? From politics to science, are we better served by passing the torch? It seems the solution to staying young forever could be that every generation has its time - and knowing when to let go may be humanity's greatest challenge of all.