People are similar to bacteria in one sense, i.e. there are always a few in any population who are naturally immune to certain things, therefore they don’t really “evolve”. It is just the naturally disease resistant people who propagate.
It’s adaptation, not evolution.
While caring for my husband who eventually died from Alzheimers I noticed that he was most likely to escape from the house as I was quickly trying to get dinner cooked for him. I then though of those stories of American Indian elderly wandering off into the forest in the middle of winter to die so their grandchildren would have more food.
Anyway, I have developed a theory that Alzheimer’s is actually a positive genetic survival gene. Among tribal and spread out populations, if there was a tendancy to wander off in search of food while failing from Alzheimer’s ones descendents probably stood a better chance of surviving because more food was available. This behavior on my husband’s part was about a year before he became too debilitated to be useful around the house/camp. Thus, had we been a primative encampment, he would have gone out to pee and look for food, and never found his way back just before he would have become a general burden to the tribe.
Genetically, my husband was Scottish, with some American Indian, red haired, reddish sun sensitive skin, heavy boned, pale blue eyes, very hairy, warrior temperment, and I suspect more of the Neanderthal genes than most.