If scientists want someday to make the old young again, they increasingly recognize they'll need to study young people who seem old. But when a group of researchers recently set out to define what it means to be prematurely old, they discovered that humans age at remarkably different rates, and that we start aging earlier than one might guess.
And for those who feel like they're growing old before their time, the researchers found even worse news: Young adults already showing signs of aging aren't just prematurely old; they seem to be getting older faster than the rest of us.