Evolution from the Negro to the Dutchman
Is natural selection continuing?
Alexey Aleksenko, "Snob"
Can humans evolve? On the one hand, I want to believe that they can: if with each generation humanity does not become wiser, more beautiful, kinder and healthier, why the hell do we need all this "history" at all.
On the other hand, we have to accept all the consequences of this hypothesis. Evolution, according to Darwin, occurs by natural selection. Roughly speaking, this means that in each generation there are better people and worse people, and nature has provided that the genes of better people are passed on to the next generations, and the genes of worse people have disappeared into oblivion, if possible. If you think about this concept, you will surely understand why Bernard Shaw called Darwin's theory "disgusting". And if all people are absolutely equal before nature (as we would like), then there is nowhere to take evolution and we will never get better. It also turns out nonsense.
Of course, there is a third way: maybe humanity is improving in some way of its own, not through biology, but through culture - it improves, for example, the school education system, composes soul–taking songs, after listening to which you don't want to mess around at all, or at least beats your children less often. This is undoubtedly what is happening. However, it is necessary to clearly understand the compromise nature of such progress: if genes do not change, then human predispositions remain unchanged. It is necessary to put him in the appropriate situation, and he will again break into the usual abomination – there is no need to explain this to the residents of Russia in 2015. It's scary to even think that the revanches of offended triples, like the German one in the 1930s, the "cultural revolution" in China or our current disgrace, will be repeated in the history of mankind again and again until the end of time. Let there still be Darwinian selection, which changes human nature irreversibly.
From the point of view of biologists, the question, of course, is not what we would like, but what actually exists. With a mixture of fear and hope, they look for signs of natural selection in the populations of homo sapiens. And maybe they do.
Last week, the world happily welcomed an article by a Dutch guy named Gert Stulp (Proceedings of the Royal Society B, Does natural selection favor taller status among the tallest people on earth?). Gert, together with his co–authors, was engaged in the evolution of his own Dutch people - more precisely, one of its aspects.
The fact is that the Dutch are the tallest people in the world, while their average height is growing at breakneck speed. In the XIX century, the average height of a Dutch soldier was 163 cm, today the average Dutch man is over 180 cm. Other peoples of the world have also stretched upwards over the past hundred years (at the end of the twentieth century, this process was called acceleration), but in most countries the increase in average growth quickly stopped in the 1980s, and the Dutch continue to grow.
Gert Stulp is far from indifferent to this story, since the young anthropologist himself has grown above the two-meter mark. Life is not easy for a two-meter bog, even in pluralistic Holland, and it is not surprising that this problem touches Gert Stulp to the quick.
Of course, the acceleration phenomenon can partly be attributed to improved nutrition, proper medical care during pregnancy and similar cultural factors that are fully present in the Netherlands. But perhaps there is a place for natural selection among these factors? For this to be the case, it is necessary, in particular, to show that the tall Dutch leave more offspring than the short Dutch. That's what Gert did.
In Holland, it was not difficult: there is an extensive medical database Lifelines, which includes information about tens of thousands of Dutch families. Gert and colleagues analyzed data from 42 thousand people over the age of 45. It turned out that a man with a height of 170 cm has an average of 2.15 children, and with a height of 185 cm – 2.39 children. The trend has been observed for at least the last 35 years. This is more than enough for selection.
Of course, you will say that something else is needed for selection: that high growth is determined by genes, that is, inherited. It is possible that the "genes of high growth" have nothing to do with it at all: it's just that rich people who eat better usually have higher growth and more children. In case of such objections, Stulp and co-authors tried to isolate from their data differences in the level of wealth, as well as other non-genetic factors that could be suspected of influencing growth. The addiction persisted no matter what.
The astute reader has already understood what the matter is tending to: if Stulp's hypothesis is correct, then humanity is evolving towards high growth, and the Dutch are in the vanguard. And, for example, the Portuguese and the Vietnamese are trailing behind, these are the dregs of evolution. The fact that no one reproached the guy for promoting fascism and racism, but, on the contrary, was favorably promoted in the New York Times, apparently happened solely thanks to the personal charm of this defenseless two-meter tall.
However, we will not give up before his charm and note that he did not prove the existence of natural selection, but only "did not exclude". For greater solidity, it would be nice to show, firstly, that the high growth of modern Dutch is inherited genetically. Secondly, to demonstrate that the selection coefficient of 0.1 (this is what is obtained from the data on the average number of children given in the article) is really capable of leading to such genetic changes in the population in just a few generations. So, if someone wants to criticize the work of the lanky Gert, there is nothing complicated here. It's just that he somehow doesn't have it, well, he doesn't look like a fascist at all.
Meanwhile, much more serious data about our evolution is contained in the work of Jain Mathieson, a postdoc from the laboratory of the famous population geneticist-anthropologist David Reich from Harvard. His April report at the annual meeting of anthropologists received good press, including Russian-speaking. Journalists, of course, were delighted with the main fried fact: it turns out that only 8000 years ago the population of Central Europe was dark-skinned. "We are descended from Negroes!" the journalists shouted joyfully, as if they had not guessed it before.
In fact, we learned that in historically recent times Europeans were dark-skinned a year ago from an article by Spanish scientists who deciphered the genome of a Mesolithic Spaniard who turned into a skeleton about 7000 years ago (do you know where they get DNA for experiments? From the tooth!!!) And the work that a young employee of David Reich told about is a little bit about something else.
The researcher used data on the genomes of 83 fossil humans found in Europe. He was interested in only one parameter: which human genes were most susceptible to natural selection? If you are not interested in how exactly you can find out, or you already know, skip the following paragraph in italics.
Geneticists are terribly lucky that, looking at a gene (or rather, at related genes of different organisms), they can immediately tell whether selection acted on it or not. We owe this option to the "degeneracy" of the genetic code: the fact that identical sequences of amino acids in a protein can be encoded by different sequences of "letters" in a gene. In the course of evolution, random typos accumulate in genes. Sometimes these typos lead to a change in the protein – then the protein, and with it some properties of the body change for the "worse" or for the "better". And some typos (due to the "degeneracy" of the code) do not change anything at all. Then everything is simple: if no directed selection acts on the gene, then most of the significant typos will simply be removed during evolution, since all the modified proteins will be worse than the original one. But if a gene is under the influence of directional selection at a given period of time, the picture will be reversed: substitutions that change the properties of the protein – and the organism – in the desired direction will accumulate especially quickly in it. Therefore, looking at the nature of the substitutions in the gene, it is immediately clear whether it has already reached a state of temporary perfection or is now rapidly evolving to adapt to some changed environmental factor.
Scientists have found several such genes. Indeed, among them there were as many as two genes that determine skin color, as well as the gene for blue eyes (for details, we will redirect the reader to an article in Science or a little shorter and more popular – in the British Independent). Another gene that was rapidly and directionally evolving was the LCT gene, which determines the ability to digest milk sugar (that is, to digest milk). Milk sugar assimilation is our genetic achievement of the last 4000 years. It took a little more than 8000 years for the triumph of the genes of light skin, and both processes in Europe have not yet been completed. In the European population, there are still harmful LCT alleles, which are now commonly classified as a disease - "lactose intolerance", like the hero of the "Big Bang Theory" by Leonard Hofsteder.
Interestingly, according to researchers, under the influence of selection there are (that is, there were during the Mesolithic and Neolithic) also genes that determine high growth – here we can wave a pen to Gert Stulp, the author of the work on the tall Dutch. Apparently, in Northern Europe, natural selection favored a set of genes that determine high growth, while in Southern Europe, on the contrary, nature favored the undersized. At the same time, all variants of these genes were present in the so-called "Yamnaya culture", whose representatives came to Europe 4800 years ago from the Little Russian steppes.
Why suddenly high or low height becomes an evolutionary advantage, one can only guess (this, by the way, is not at all clear from the work of the lanky Dutchman). But how did we Europeans evolve so quickly from dark-skinned to white, and even acquired the ability to drink milk along the way? We are not racists, and therefore it is not obvious to us why whites are so much better than blacks to defeat them so quickly in an evolutionary battle (even if it was not people of different races themselves who fought, but only their genes). And, by the way, this milk was given to us, if you think about it: in many poor and hungry regions of the world, they do fine without it.
There is a reasonable explanation that explains everything at once. And it's very short: rickets. The fact is that it is much less sunny in Europe than in the parts from where our ancestors came to it. Less sun means less vitamin D, less calcium for bone growth, in the worst case, children grow up to be mentally retarded shorties, and if a girl survives, her pelvic bones narrow - and she is unable to give birth. Apparently, this was a fairly strong factor of natural selection, which was reflected in the genes of fossil Europeans.
To fight rickets, they had two options. Firstly, to make their skin let in more sunlight and vitamin D could be synthesized even in cloudy Scandinavia. Secondly, to get vitamin D, and immediately together with calcium, from animal milk. According to the data of the guys from the Reich laboratory, nature enthusiastically used both of these opportunities.
Thus, two scientific papers at once – one simpler, one more complicated – hint to us that natural selection in humans has been taking place for the last 10,000 years and seems to be continuing now. However, instead of forging a race of superintelligent superhumans, he is busy with more prosaic problems: he makes us more adapted to the not too favorable conditions in which we live. If we recall that selection has been doing about the same thing for the last billions of years, Darwinian evolution no longer seems as sinister and misanthropic as it seemed to Bernard Shaw.
On the other hand, it is not necessary to place high hopes on natural selection in terms of the wiser and better humanity. Perhaps people really should try palliatives here: write more kind poems, draw beautiful pictures and beat children less often. Their genes, of course, are so-so, but what they really have. Historical experience shows that the same genes can make a "Pit culture", and maybe Holland. It remains to make your choice – and go ahead
Portal "Eternal youth" http://vechnayamolodost.ru17.04.2015