What causes aging?
Aging is a side effect of being alive in the first place. Let's say, our metabolism, a very complicated network of molecular and cellular processes which keep us alive from one day to the next or from one year to the next. Metabolism has side effects. And these side effects some of them are naturally repaired and reversed by other metabolic processes, but some of them are not. A few of them, the ones that accumulate very, very slowly, evolution has not needed to do anything about them because by the time they start to matter in terms of our health, most of us in awhile would be dead anyone of starvation, you know hypothermia or whatever. So aging is the accumulation of very slowly accumulating molecular and cellular side effects of metabolism.