Lifespan, a book by Harvard scientist David Sinclair, has become an influential source of misinformation on longevity, featuring counterfactual claims about longevity genes being conserved between yeast and humans, the existence of supposed activators of these genes, and claimed successful age reversal in mice based on partial reprogramming. The book has popularized a stack of drugs and supplements with significant potential to harm the general public.The reviewer suggests that scientists and physicians emphasize to the general public that aging is known to be a highly polygenic developmental process and that the most important things that people can do to age better are to maintain high physical and mental activity.