Fascinating item about how some Europeans had mutated genes which allowed them to survive the Black Death, which they passed on to their descendants, along with an increased susceptibility to autoimmune conditions:
npr.org/sections/goatsandso...
By the way, this took place over decades, so anyone hoping for herd immunity to SARS-CoV-2 better not hold their breath!
We can't get herd with the virus that keeps mutating.Its going to be here for awhile I think.
I think the idea of herd immunity has been rubbish from the beginning. Even if we had an effective vaccine which prevented both contracting and transmitting covid there's not enough impetus to vaccinate everyone in the world. look how many years it took to eliminate Polio and Smallpox, and that was before massive antivax sentiment!
I thought it was genes inherited from Neanderthals that affected our immune system's response to things
thanks. most interesting
It's natural selection - some people had a natural ability to survive the infection and develop their own boosted immunity, If it was a genetic feature then they passed it on to their children so when it appeared again they also tended to survive. Because of the large numbers of deaths the gene pool became smaller and it was reinforced.
Trouble with PMR is that it usually appears after reproductive age, so of course could not be eliminated by natural selection.
But PMR doesn't kill us off!
One time I watched a tv show about recording as many different populations as possible across the world. It was a race to get undiluted samples as population mixing is occurring so rapidly now. I remember there is a population group somewhere in Asia which has the most resistance to diseases of anywhere else in the world. The researchers speculated that the ancestors of this group were themselves descended from individuals who survived migration through nearly the entire world, getting exposed to many pathogens, and thereby were the most resistant to diseases.
Autoimmune disorders
Additional autoimmune disease now.
PMR and Parkinson's Disease
Could psychosis be an autoimmune disease?BBC IPLAYER 
