Andrew Huberman· PhD
You are as old as you look, if you want to generalize. So let's start with centenarian families. These are families that tend to live over a hundred. When they're 70, they still look 50 or less. So it is a good indicator. It's not perfect because you can like me growing up in Australia and accelerate the aging of your skin. But in general, how you look, and no one's ever died from gray hair, but overall you can get a sense just from the ability of skin to hold itself up, how thin it is, the number of wrinkles.