Gene compatibility for making babies

I presume that the common reason why multiple variants of a gene persist is because variants of one gene work variably with variants of other genes.

To take the simplest case, suppose there are 2 relevant genes, and the first has variants A and X, and the second has variants B and Y. And suppose that either combination  AB or XY is good and will make a successful individual, but combinations AY or XB work badly. Even though AY and XB people don’t have many offspring, still they keep coming.

The way evolution tries to handle this is for gene combinations to also cause detectable changes, and to cause detection systems that respond to those changes. In humans this is done in part by smell. So perhaps B people will smell different from Y people, and A people will prefer the smell of B people and X people will prefer the smell of Y people. But obviously there are a lot of genes and this has to be a rough process.

We now have the opportunity to help people find compatible partners, so that no AY or XB babies are born. We also have the opportunity to make some big mistakes. For example if AB people are actually better than XY people (according to some evaluation), then it might seem like a good idea to get rid of X and Y completely so there is no problem. But having multiple variants gives us robustness. Suppose a new beneficial variant of a 3rd gene arises. It may be that it works best with XY individuals rather than AB individuals. If we get stuck with only AB people then maybe we lose the option of benefiting from that 3rd gene variant.

It is not impossible that our 3rd gene variant solves the problems that AY people have and actually works best with them, but is that a good reason not to help people find compatible partners?

The rise of tribalism (and how it helps the rich)

We observe that the Democratic Party in  the USA is more likely to take actions that help poor people, while the Republicans like to help the rich. Yet a lot of poorer white folk vote Republican, so that the poorer states often have Republicans in power, amplifying the bad outcomes in those states. This is typically perceived as voter stupidity. This seems unlikely given 100s of thousands of years of human evolution favouring intelligence. We need to look deeper.

Humans have triumphed in the boom and bust cycles of the Earth's last few million years. What is likely to be a good strategy? When things are good we have lots of kids, and send some of them off to explore and settle. When things are bad the population has to shrink. What do our genes want us to do then? The higher status individuals are most likely to survive and reproduce. So the genes for low status individuals will like it (metaphorically) if it is closely related high status individuals who survive, as opposed to more distantly related individuals. So we should have an increased willingness for low status individuals to make sacrifices to promote the interests of high status individuals in their tribe against other tribes.

But how do we identify relatively more closely related individuals in large societies. In addition to the standard cultural identification (similar language, accent, facial expressions, attire, hair style), it is natural that people take notice of similar appearance.

The rich in America, at least the visible ones, seem to be mostly of European origins. So perhaps there is a reason for poor whites, feeling (mostly incorrectly) that things are going bad, to support the Republican party and its support for hereditary wealth. And perhaps it is instinctive for the high status individuals to promote tribalism. It's certainly working for them today, but as we saw in Europe in the 30s, it can easily get out of hand.

So it would be possible to attack Trump's support by identifying wealthy foreigners and those of non-European heritage who will profit by Trump's and wider Republican plans. Of course this contributes to inflaming social tensions, and should not be used unless there seems to be some chance of Trump winning. After the election we hope Democrats in Congress will move vigorously to address the decline of the middle class, most particularly by printing money and spending it on much needed infrastructure.