24 July 2019

DNA and its man (1)

Will the genetic test indicate a Russian person?

Alpina Non-fiction Publishing house publishes a book about practical genetics. TASS publishes an excerpt about consumer tests, which can be used to judge the origin of a person, but with important caveats.


DNA was discovered in the XIX century, its structure – the famous double helix – in the early 1950s, and the human genome was deciphered in 2003. Now anyone can use the achievements of genetics for a relatively small amount and learn something about themselves (DNA has been used to identify a person for longer, for almost 40 years). The book "DNA and its Man: A Brief History of DNA Identification" by scientific journalist Elena Kleshchenko is about this: a little theory, and then all kinds of applications of genetic methods in practice, such as forensic examination of the remains of the Romanovs, the search for serial killers, etc.

In the above passage, we are talking about the search for distant ancestors and nationality. To understand it, you also need to understand several terms. The testing method is based on checking the male Y chromosome. It looks for specific differences in one letter of the genetic alphabet, and sometimes also characteristic repeats in DNA (something like grooves on the pads of the fingers forming a unique pattern). Together, these features make up the human haplotype, and close haplotypes form a haplogroup. By how many repetitions and "typos" two people have, one can judge their closeness: they may be relatives or, in any case, compatriots. But not everything is so simple.

Type the words "haplogroup" in the search engine, and Google will tell you: "Russian haplogroup", "Armenian haplogroup", "Jewish haplogroup" ... Alas (or rather, hurrah), not everything is so simple. For example, haplogroups A and B do occur mainly among African peoples, and A is characteristic of Ethiopians, San (Bushmen), Koi-koin (Hottentots) and Nilots, and B – for Pygmies and Hadza, haplogroup M and S – for New Guinea, Melanesia, Eastern Indonesia. But in the melting pot of Eurasia and America, everything is mixed up: for many centuries in a row, people travel, emigrate in groups and singly, start a family and die not where they were born, but in the era of globalization… One hears, for example, that haplogroup R1a, aka R-M420, is "Russian", "Slavic", etc. However, it is found not only in Russia, Belarus, Ukraine, but also in Estonia, Hungary, Norway, India, Pakistan, among the East Germans, among the indigenous population of the Faroe Islands… By the way, it arose long before the appearance of the Slavs. Indeed, its occurrence in Russian populations is quite high – from a third to a half. But it is still more correct to say that this haplogroup marks certain ways of human migration.

So is it possible to establish nationality by haplogroup? For representatives of small nations that do not mix with others and are well studied by geneticists, apparently, yes. As for the citizens of large European and Asian states, the person belonging to haplogroup R1a does not give much information – this person is quite likely to be both Russian and German ...A study on a wider set of markers will tell you that the ancestors of a person most likely lived in a certain region of Eastern Europe. But it is clear, in the era of globalization, it is not necessary to assert with full confidence that he himself was born or lives there.

Today, Y-chromosome research is a fairly common commercial service. Such a study allows you to establish the degree of kinship in the male line between two individuals; there is a chance to find very distant relatives if they also used this service and do not mind sharing information about themselves with potential relatives.

By the way, we recall once again that the surname in most countries is transmitted in the same way as the Y chromosome - from father to son (of course, except in cases where the passport relationship does not coincide with the biological one), and there are databases in which Y–STR are directly compared with surnames: absolutely a logical step after all the "family" affairs. Thus, citizens are suspects, let's take a note: all men in the genomes have a page with passport data that cannot be faked! Right with the "last name" column, and even if you changed it, the trace can still lead to you.

Yes, and about the "haplogroup of Jews". As with all large nations, Jews have different haplogroups, but it's worth telling about one. Cohens are a class of priests in Judaism, according to tradition, descendants of Aaron, the brother of Moses, who served first in the Tabernacle, then in the Jerusalem temple. Cohen's status is inherited on the paternal side (subject to certain restrictions and prohibitions). The origin of the Cohens is indicated by the surnames Kogan, Cohen, Kan or Kon, Aronin, Aronov, Baron ("bar Aaron" is the son of Aaron) and many others, in all languages of the world. The idea to see what all these people have with the Y chromosome was on the surface. Indeed, about half of the modern cohens belong to the J1-ZS223 subclades. Now the "Cohen haplotype" belongs to the sub-haplogroup Z18271, and the lifetime of the common ancestor, who was named, of course, Y-chromosomal Aaron, is estimated at 2638-3280 years ago.

Women who want to find out something about their male ancestors can "borrow" the Y chromosome from relatives - father, brother, uncle from dad's side... It was at the request of a relative in 2012 that two African Americans sent their genomes to Family Tree DNA in Houston, Texas. (Let's remember this name, we will meet it more than once.) The requests of African Americans pose difficult tasks for genomic genealogists. Non-genetic clues about which tribe the slavers drove into the hold are usually scarce, if at all, about some tribes it is unclear whether they exist in modern Africa, besides, the collection of African population and genetic data is not as far advanced as in Europe. But this result turned out to be especially impressive: the Y-chromosome was absolutely unlike the previously known ones, it had no place on the family tree – neither an ancestor nor a descendant of others, but an independent line that separated from the common trunk before anyone else. "The chromosome of another Adam has been discovered," the journalists wrote, although it would be more accurate – "the chromosome of the unknown son of Adam." The new haplogroup was named A00, and the unofficial name was preserved – "Perry's Y chromosome" (Albert Perry was the name of the common ancestor of the study participants who lived in the early XIX century). Of course, Perry from South Carolina are not descendants of aliens or Atlanteans, their haplotype, although rare and ancient, is quite human. Then the same haplogroup was found in 11 men of the Mbo tribe (Western Cameroon). This, of course, forced to increase Adam's age: the more diverse the descendants, the earlier the ancestor had to live. So "civil science" helped fundamental science, and family genealogical research redrawn the family tree of mankind. Perhaps this is not the last such case. There are billions of people on Earth whose genomes no one has read yet.

Returning to the topic – the Y chromosome is important for genealogy, but to find out from which regions your ancestors come from on different lines, you will also need to study mtDNA and non–sex chromosomes - the Y chromosome gives only one line. The carrier of the Y-chromosome haplogroup R1a may also be a Negroid if he had a Russian great-great-grandfather on the male line, and all other ancestors were residents of Ethiopia.

In general, with a sufficiently large set of markers, it is possible to establish ethnic origin by DNA, but such things are done more for the sake of personal or scientific curiosity, and not for the correct filling in the "nationality" column. You can select some special markers from these markers and say something about a person's appearance, for example, about the color of his skin. (Criminologists sometimes need this when they are trying to determine who owns an anonymous sample of biomaterial from the crime scene, and we will return to this topic later.) But, as we know from practice, guessing nationality by appearance, although fascinating, is not very effective.

It is more practical to distinguish one's own from others by cultural characteristics: what insignia he wears, what gods he believes in, or as in the Old Testament: does a potential friend pronounce words that the enemy does not know how to pronounce. "... And the Gilead intercepted the crossing of the Jordan from the Ephraimites, and when one of the surviving Ephraimites said, 'Let me cross,' the inhabitants of Gilead said to him, Are you not an Ephraimite? He said: no. They said to him, "Say shibboleth," and he said, "shibboleth," and could not pronounce it otherwise. Then they took him and killed him at the crossing of the Jordan. And forty-two thousand of the Ephraimites fell at that time..." (The Book of Judges of Israel. 12:5-6; there was no "sh" sound in the Ephraim dialect of the Hebrew language). And it would be best, of course, not to engage in such Old Testament nonsense at all.

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