By Thomas R. Kestler Age. It’s just a number, right? Turns out, there’s a lot more to it. Our chronological age clock started ticking the day we were born. And, with each circumnavigation of the sun, our chronological age adds one year. Pretty simple. But, over the last decade or so, the medical community has begun paying attention to our biological age. Biological age is defined as an estimate of the individual’s position with respect to his or her potential life span. Biolo