TL;DR
Turning back the clock on an aging body now has a deadline, a scoreboard and a $101 million purse. XPRIZE Healthspan asks teams to restore at least 10 years, ideally 20, of muscle, brain and immune function in adults aged 50 to 90, within a year of treatment. Twenty finalist teams are now running human trials through 2029, and up to $81 million goes to a grand-prize winner in 2030. That gives age reversal a dated, head-to-head scoreboard in people, judged on what bodies can actually do. If even one team clears the bar, "slowing aging" stops being a lab-mouse promise and becomes a measurable treatment. If none does, the prize will still show which approaches fail, and why. The open fight is over measurement: there is no agreed way to score aging itself.
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 "Any Healthspan finalist reports interim human results by 2027"; and every source.