> Almost all diseases that happen after a species' reproductive age is very difficult to select out either in a positive or negative way unless it happens to be

> Almost all diseases that happen after a species' reproductive age is very difficult to select out either in a positive or negative way unless it happens to be strongly genetically linked (either through sharing genes or being very close on a chromosome) to a different positive or negative trait. Well that's not entirely true. I think humans evolved (and still evolve) on a tribal level. So an individual's traits that strengthen the tribe are also good for the survival of the tribe since one's entire gene pool would be wiped if the neighboring tribe killed all of you, even if the individual is post-reproductive age. I find that most people never talk about evolution on a tribal level like this.