TL;DR
A big slice of the longevity world rests on one idea: cells take out their own trash less well as people age, so helping them do it should slow aging. Fasting regimens, the drug rapamycin and a billion-dollar startup's first pill all lean on it. Now researchers have measured that cleanup directly in human cells, and it does not behave the way the theory says. It depends on the kind of cell and on sex, and in people 70 and older, more of it went with weaker bodies, not stronger ones. That is a small study showing a link, not proof. But it means the most popular target in aging research may help the young and harm the old, and the drugs aimed at it will need to prove which.
Below the line, for paid subscribers: The full story: where it stands, how we got here and what's dated next; our Odds board on 4 milestones, starting with "Retro Biosciences reports results from RTR-242's higher-dose groups by 2027"; and every source.