What happened to the Neanderthal?

Here is a hypothesis based upon three observations.

1) Our Neanderthal genes all come to us from through the male line (suggesting Neanderthal women plus modern human men did not equal healthy babies)

2) Neanderthal were much more likely than stone age modern humans to practice incest. Incest, as we all know, is something modern humans are hardwired to avoid. If two children who are not blood relatives are raised together, chances are they will not have a sexual relationship later in life. If you consider genetic disease prevention strategies common in Africa such as sickle trait and thallesemia trait (both of which protect against the great scourge malaria) i.e autosomal recessive traits which are great if you have just one copy of the gene but lethal if you have two, then obviously modern humans benefit from genetic diversity and die out if they become inbred. However Neanderthal DNA hardly changed at all ( compared to modern human DNA) over a hundred thousand years. And the race thrived for hundreds of thousands of years without genetic diversity. And incest did not doom them to extinction. Humans did.

3) What parts of Neanderthal DNA survived and were incorporated into modern humans? I.e what was the best part of Neanderthal, the part that made modern humans better, too? Their immune systems. Neanderthal were just naturally resistant to a wide variety of diseases. The same genes gave them autoimmune diseases, too. But in the days before antibiotics, infectious disease resistance was the key to survival.

Now, put these three observations together 1) Neanderthal women could not successfully breed with modern human men but modern human women had no problem breeding with Neanderthal men 2) Incest and lack of genetic diversity was actually better for the Neanderthal than genetic diversity and 3) Neanderthal had an extremely strong immune system, and what do you get?

Neanderthal women had such strong immune responses to foreign proteins ( derived from foreign DNA) that their best chance of having successful pregnancies was if they mated with someone who had a close matched genome (i.e their brothers). If they attempted to mate with someone whose proteins/DNA were extremely foreign, their bodies would react to the fetus as if it was a deadly infection, spontaneously aborting it. Or creating antibodies that would doom any subsequent pregnancies by the same father. So Neanderthal women who mated with modern human men in the new more open more diverse societies would have had serious infertility issues. But if Neanderthal women decided to stick to their brothers and somehow a gene like sickle cell trait slipped into the family from the newly arrived Africans, that would also impair the Neanderthal women's ability to successfully procreate, too.

I think that this might be the math that eventually led Neanderthal to disappear except as a few genes in our modern human DNA.

PS. There is another, worst case scenario. Modern human women are more likely than men to develop certain autoimmune disorders and they do it after being pregnant. What if exposure to all the foreign DNA caused Neanderthal women to develop autoimmune diseases like Lupus? In that case, Neanderthal women would die at higher rates than modern human women, speeding up the extinction of their species.

To tell the truth, I am relieved. Beto is too pure, too idealistic to be a candidate. He can do more good for this country as a civil rights leader. He has a very promising future ahead of him. Carry the dream, Beto! I have faith in you!



Oh, and you will note that I am now an Elizabeth Warren supporter. Let's hear it for the next POTUS, Warren!