By Tanner Garrity It’s common for us to sigh in disbelief when someone dies at what we perceive as a premature age. We say, “57? Oh, man. He was so young. That’s really sad.” But that line of thinking presupposes that one’s chronological age is the ultimate indicator of one’s longevity. In reality, birth date might not matter nearly as much as your behaviors — how you work, how you eat, how you sleep. One’s lifestyle produces the more accurate biological age. The late 57-year-old might have had the epigenetic markers of a 75-year-old. How to zero in on that number, though? Aging clocks, which …