Your Real Age, Decoded: Inside the Race to Build a Clock That Actually Tells How Old You Are (opens in new tab)

This review maps the entire toolbox for measuring “biological age” — from a stopwatch timing how fast you walk, to DNA methylation clocks, to AI that guesses your age from a selfie or an ECG — and argues that despite impressive mortality-prediction power, almost none of these tools have yet been proven to change when you intervene, which is the one thing that matters for longevity medicine. Two people can share a birthday and yet be biologically decades apart. One climbs stairs two at a time ...