Human Evolution

by radimentary

Disclaimer: I am not an evolutionary biologist by any stretch of the imagination. Disclaimer 2: Although I have very little confidence in the conclusions expressed in this particular post, people may be justified to call me a racist bigot anyway. I absolutely do not endorse hurting real people for the sake of evolution even if it would work.

Here’s a fun little explanation for something you might see if you go to college in America. Let me start by building the theory and see if its predictions match up with the realities.

Darwin said the two fundamental pieces of evolution are selection pressure and genetic variation. I think everyone can agree that the human gene pool is the largest and most diverse it has ever been. The problem is – there are very few selection pressures comparable to the kinds of pressures on humankind in prehistoric Africa. It is reasonable to imagine given these circumstances that human evolution has relatively stagnated in the last several thousand years – a world where the vast majority of people end up surviving to adulthood and reproducing.

Here are a few other nuances about evolutionary theory before we start applying it to human history. We learned in grade school that evolution happens on the timescale of millions of years, and two thousand years of history couldn’t possibly make a dent. Here are two counterpoints I want to make to this. First, on the level of individual alleles really visible differences can happen over a few generation. This is easy to see from race: the differences in skin color etc. are traced to at most a couple hundred thousands of years.

Second, one of the most important modern contributions to evolutionary theory is called punctuated equilibrium, which runs counter to Darwin’s notion that natural selection happens gradually and uniformly over time. Punctuated equilibrium tells us that a species remains relatively stagnant for most of its history, but rare and extremely stressful events such as the meteor that killed the dinosaurs (and 90% of everyone else) cause rapid bouts of evolution by introducing unheard-of selection pressures in comparatively very short time spans. The fossil record strongly supports this theory, that the vast majority of speciation events and real evolution occurs in concentrated bursts.

So here’s our model for how evolution works in general: for long periods of time, barely anything happens because there are no real changes in selection pressures. This is probably more true of sedentary agricultural human society than for any other species that has ever existed. When short severe selection pressures occur, the kind that suddenly wipe out (but not indiscriminately) more than half of your population repeatedly, evolution happens in rapid bursts.

So how about human evolution in the last millenia? Has anything really happened? Humans as a whole have not experienced any serious dip in population since the history of forever, so the answer must be no.

But this is a simplistic view because it doesn’t take into account that many groups of people have been so isolated reproductively from each other that for the purposes of evolutionary study they are essentially different species. And without a doubt these people have had massive existential crises.

As a casual student of history I can point out two groups of people against whom serious attempts of genocide have occurred repeatedly – the Chinese and the Jews. Let’s start with the Jews: they are a perfect example because they had a small population, historically rarely interbred with surrounding populations, and were just persecuted and killed all over the place. Pogroms happened in Europe for at least a hundred years before Hitler. And some two thirds of European Jews died in the Holocaust alone.

Very much the same can be said about China in the last two centuries. After an entire millenia of brutality by various groups – the Mongols, the Manchus, ethnic Han Chinese ourselves – starting in the 19th century Western and Japanese imperialism, and later on Mao, killed a lot of Chinese people. This is a long and awful chapter of history – starting before the Opium War, going through various neocolonial shenanigans, highlighted by the atrocities committed by the Japanese, and ending in the tragic lunacy of Mao – someone I might consider an incredible hero had he only died two decades early.

I don’t want to go too far down this road but the point is that these are repeated genocides against populations of humans and there can be no question that some divergent evolution occurred, although its scale and its direction are certainly more suspect. I would argue that the kinds of pressures experienced by the Jews and Chinese selected for traits like intelligence, tenacity, resistance to mental illness and these are reflected strongly in their phenotypical differences especially in the United States and to a lesser but still significant extent worldwide. Jews and Chinese Americans dominate the top colleges these days and get the highest-paying jobs out of any race. Chinese Americans experience the lowest rates of mental illness. I could go on.

Now buckle in, because there are a lot of caveats.

First, the immigrant population in America is not representative of the worldwide population. This is obviously true for the Chinese, as the vast majority of recent immigrants are highly educated and skilled workers due to American immigration policy. The outcomes in China proper are certainly less absurdly skewed – but still there is some evidence that Chinese people overall have higher average IQs than any other race. Other immigrant groups also face similar barriers of entry and fail to perform the same way as Chinese immigrants. Furthermore, I don’t think this can be very true about American Jews, especially since more than 40% of the world population is here.

Second, it can be argued that much of Chinese and Jewish success can be attributed not to genetic differences, but to memetic – i.e. cultural – differences. I think these two are very difficult to disentangle, but to do so is also besides the point. It is clear that culture is heritable and much harder to transmit than one might imagine, and that it reacts to genocidal massacres if anything more rapidly than genetics. I would argue that many of the obviously superior cultural memes in Chinese and Jewish cultures are a direct consequence of the evolution aforementioned and probably the bigger part of all the evolution that occurred. Chinese culture has certainly evolved substantially and rapidly, as Chinese people a few centuries ago were comparatively culturally backwards just like the rest of the non-Western world of the time.

Third, other groups of people have also suffered historically for long periods of time and fail to have the same outcomes. I know too little about history to fully defend this point, but I would imagine that groups of people that experienced more than one genocide are pretty rare and come out genetically and memetically richer for it. Also a significant nuance is that genocide is not enough: the actual selection pressures involved – if any existed – must be examined on a case-by-case scenario. A nuke dropped on Hiroshima did nothing for the Japanese. The awful things done to black slaves in America probably did not end up selecting for intelligence – there is evidence that slaves that were too smart were actively culled. It’s not obvious that all of the awful things that happened to Jews and the Chinese were positive from a genetic point of view.

I think I will stop here, but hopefully I have opened the door to a fun and morbid way of examining history grounded in evolutionary science.

 

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