For just about his entire life, Ron Smith has been a subject of a scientific inquiry. At birth, in 1972, he was studied by scientists, and then assessed again at age three to document his physical fitness, mental health and intelligence. Every few years after that, he has returned to be poked, prodded and tested in the name of science. This year, Smith will turn 45.
Now, this detailed catalogue of biological data is helping researchers answer one of the most perplexing scientific questions of all time: Why do some of us age gracefully, while others find that their bodies begin an inelegant process of failure long before death?