What is Biological Age, and Does it Tell Us Anything Useful?

For some of us, our cells may look much older than the calendar suggests

Both of these humans have the same genetic instructions. Why does one have less hair and more wrinkles? Photo by Johnny Cohen on Unsplash

HHave you ever noticed that some of your friends, who are the same age as you, might seem older?

Maybe their hair has started graying before yours. Maybe they aren’t as fit and can’t keep up on more strenuous hikes. Maybe their skin shows more age and wrinkles.

Two people can be the same age, according to calendars, but seem quite different in physical appearance. There’s another way of measuring age, one that doesn’t use birthdays, employed by biologists. It’s called biological age, and it can help researchers test whether a treatment would let you live longer — but the term is also used to scam you out of money.

Are your cells running fast?

Humans and animals have innate clocks. It’s how you can (sort of) tell time, even in a windowless room with no clock or smartphone. It helps us know when we’ve been awake too long and should take a snooze. But over a longer period (years to decades), our cells track a different sort of time.

Like a sailor tying knots in a piece of rope to count days, our cells slowly add or remove markers from locations on our DNA.