@Cruiser Choosing mates from other villages has nothing to do with being monogamous or not. I’m monogamous and my mate is from Mexico, with a gene pool from the Iberian peninsula, France, and the Middle East. My background is primarily Eastern Europe, with a mini bit of Western Europe.
Even way back in history a man could couple with a girl from another village and stay with her long term.
It’s probably the willingness to be with someone outside the village that is important, which points to attitudes about “outsiders” and people who are different, not so much whether they are monogamous or not. Unless you are saying cheaters are more likely to have sex with people not of their own kind so to speak? That still has to do with social boundaries though.
It’s bigger than the village. Native American tribes suffered big losses when the Europeans came, but probably if more of the Native Americans had crossed tribes it would not have made a huge impact. The impact would come from making babies with the Europeans. Plus, I am not even sure how much impact that would have because the Europeans died from those diseases also. One of the big killers was small pox. The point about the Europeans coming to America is not that the Indians didn’t have immunity to that, it is that the American continent seemed to be free of that horrible disease. Just like that idiot in Brazil who brought over African bees (on purpose) now we have bees that kill the majority of pekple and animals from just one sting. It would have been nice if they kept that on the other African continent. Europeans might have done slightly better living through smallpox and some other disease because of their farming practices and because for many years they were being killed off by the diseases and the people with the better immune systems survived. Still, a lot of people died in Europe.
Look at AIDS, very few people are immune, and I am not sure they have confirmed there is immunity. I know science has researched the gene that believe caused immunity for bubonic plague, I think the mutation is called Delta 32, as giving immunity to HIV. They believe people who were homozygous for the gene don’t get sick. I know someone who never got sick from HIV while his lover and friends all died off. He has been positive for 30 years. It might be argued that its good his parents stayed in the village and both had the gene. Although, I understand your point also that if there are exponentially more heterozygouse people eventually there is a tipping point where the population is more likely to have more homozygous people. But, take red heads. The best way to produce a red head is for both parents to be red headed, then it is guaranteed. Red heads who marry brunettes, run the risk of their grandchildren not having the red gene.
Anyway, we are much much more intermixed now and AIDS still wreaks havoc and so would small pox. For that matter, so does measles, and there are others. Vaccines are what helped us the most, also being exposed to the disease at the safest ages helps. An infant or elderly person gets whooping cough, higher chances of death. An older child, or otherwise healthy adult, more likely to live. Once you get it, you’re immune.
Same with Spanish flu, it simply was a very deadly virus for many many people in many many villages.