An interesting fact is that you mentioned he had never had kids. In my biochem class when we were discussing natural selection and such, my prof was telling me about some research he had been involved with in terms of lifespans being potentially linked to when a species procreates. I won't get into all the details, especially since he admitted that there was nothing extremely concrete to go on yet, but basically the research had thusfar suggested a strong link between procreation, and times of death. Essentially the idea that once you have kids, nature has you on the chopping block to die. It seems to me that potentially this might have played into his longevity, as the study appeared to show an increase in lifespan with a delay of having kids (at least in the animals they tested.)
Just a thought