Have you ever wondered how and why we age? That is among the key questions on aging. Another is whether all our cells age at the same rate along chronological time. These questions have puzzled scientists for years.

Could knowing the "aging clock" allow us to slow or roll back biological time? We're closer to an answer. Researchers found a means to track our cells' biological age by comparing DNA methylation between healthy and cancerous tissue. The process of DNA methylation is how our cells control which genes are active at any given time.

This gave researchers a comprehensive look at changes in the cells which allowed them to track time. After examining eight thousand samples from fifty different human tissues around the body, they found while most tissues' biological age matched their chronological age, some did not.

A woman's breast tissue is two to three years older than her other tissues. In a woman with breast cancer, the adjacent healthy tissue is up to twelve years older than other body tissue and the cancer cells themselves are thirty six years older. This could explain why breast cancer is prevalent and why we all face greater cancer risk with age.

Plus, our biological clock isn't constant, going much faster from birth through adolescence, then slowing to a more constant rate in our twenties. As for our stem cells, they are the age of newborns. That means if adult cells are reprogrammed into pluripotent stem cells, which we can do in the lab, these cells' biological clock get reset to zero!

Could we actually tap into a real fountain of youth? We are of course getting way ahead of ourselves. But with these discoveries, it is not far-fetched to contemplate slowing or reversing the aging process.