In Greek myth, the amount of time a person spent on earth was determined at birth by the length of a thread spun and cut by the Fates. Modern genetics suggests the Greeks had the right idea—particular DNA threads called telomeres have been linked to life expectancy. But new experiments are unraveling old ideas about fate.
The DNA that makes up your genes is entwined in 46 chromosomes, each of which ends with a telomere, a stretch of DNA that protects the chromosome like the plastic tip on a shoelace. Telomeres are quite long at birth and shorten a bit every time a cell divides; ultimately, after scores of divisions, very little telomere remains and the cell becomes inactive or dies. And because elderly people generally have shorter telomeres than younger people, scientists believe that telomere length may be a marker for longevity as well as cellular health.
View the original article here: Can Your Genes Predict When You Will Die?