A new study claims that people age at very different speeds.

The Henderson twins. (stock photo)

Have you ever felt older than your years? If you're like us, then you answered, "Unnggghhh yes, ohh the pain." But as it turns out, we're not all just whiners. There's some science behind that awful feeling.

A new study published in the journal Proceedings of the National Academy of Sciences found that people have a "chronological age" and a "biological age," and that these numbers can be radically different. Some subjects in their late 30s had the bodies of people ten years younger, while others seemed to be approaching retirement age. Some seemed to age three years for every year that passed.

Sources: BBC