But I was particularly taken with this post (and the ones that link to it) on the idea that as a psychological matter, people tend to live "different lives" roughly as a function of our doubling age. On a completely unscientific basis, the idea kinda fits my experience, anyway. Still more interestingly, however, the post links that idea of a psychologically "new" lifetime with every doubling, with the famous Gompertz law of human mortality, which does have a surprising amount of empirical observation. It says that the probability of dying in a given year doubles every eight years. Taken together:
If you try to come up with an equation for probability of survival vs. number of lifetimes lived, you get an almost absurd exponential within an exponential within an exponential. (Cool graph in original post.) That, in my book, is extreme fairness. Virtually all of us get to live to the end of our seventh lifetime, but almost none of us get to complete the eighth [which begins at age 48 and ends at age 96].