In the photo: The mummy is in the state that people first found it.
The "Ice Man" Otzi, who had been lying in the alpine ice for 5 thousand years, belonged to an ancient family whose foremother lived about 20 thousand years ago. Apparently, the genus was interrupted: the mitochondrial DNA of the mummy, completely deciphered by scientists, is not similar to any known mtDNA of our contemporaries
The results of a complete deciphering of the mitochondrial DNA of the most ancient of modern people - the famous Tyrolean Otzi - will slightly upset those who would like to consider themselves relatives of the "Ice Man".
According to Italian scientists and their British colleagues, who deciphered the mitochondrial DNA of the mummy, none of our contemporaries belongs to that rare branch of humanity, to which Otzi belonged. At least none of those thousands and thousands of people whose mtDNA has been decoded.
The body of Otzi, or Zimelaun Man, was discovered in the Alps in 1991. The mummy frozen into the ice turned out to be an excellent material for a great many studies, but despite the recurring details about the "star" person from the Neolithic, the secrets of Otzi's life and death still excite a huge number of people. Some of our contemporaries, impoverished in mind, even believe in his supernatural abilities, which are manifested in our time in the form of the so-called "curse of the mummy."
Mitochondria is an organoid of the cytoplasm of animal and plant cells in the form of filamentous or granular formations. Consists of protein, lipids, RNA and DNA. The main function of the mitochondria is to generate energy ….
The very first genetic analyzes, carried out in 1994, showed that Otzi belongs to the mitochondrial haplogroup K, which is distinguished by several characteristic nucleotide substitutions in the DNA of the "intracellular power plants" - mitochondria. The probability that these and only these substitutions will occur during random mutations is very low, so that people belonging to the same haplogroup are very likely to have a single origin. Moreover, in the case of mitochondrial haplogroups, we are talking about maternal kinship - all mitochondria to the human embryo are inherited from the mother.
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Haplogroup K, which includes about 8% of the total modern population of Europe, is one of the branches of the haplogroup U, widespread in the western part of Eurasia. In turn, K is subdivided into two clades - K1 and K2.
To find out which of the two Otzi belongs to, small scrapings from the rectum of frozen Tyrolean helped.
Eight years ago, on September 25, 2000, in the Archaeological Museum of South Tyrol, Otzi was thawed for the first time in more than 5 thousand years. They thawed the Ice Man to find out what his last meal consisted of, but along with the DNA of plant and animal origin, Otzi's own DNA was found in the intestines. Franco Rollo from the Italian University of Camerino, who received 70 mg of Neolithic man, also participated in this work.
Decryption methods.
To fully decipher the mitochondrial genome of Otzi, the researchers used the method of high-throughput pyrosequencing 454, based on the determination of pyrophosphate, which is formed when …
Rollo also led the current study, during which scientists completely decoded Ice Man's mtDNA, collecting it from nearly three hundred fragments, chemically multiplied in a test tube. The results of the new analysis are published in Current Biology.
After sequencing individual sections of mtDNA, scientists found that Otzi belongs to haplogroup K1, possessing all the point nucleotide substitutions that define it.
However, several other mutations of the "Ice Man" do not allow attributing it to any of the three known branches of the haplogroup - K1a, K1b and K1c.
In total, scientists found 30 differences between Otzi's mtDNA and a standard reference genome.
According to Rollo, despite the fact that Otzi lived relatively recently, the ancient inhabitant of the Alps was genetically significantly different from modern people. This does not mean that Otzi possessed some unique mutations, it is just that a separate phylogenetic branch previously existed - a group of men and women with the same mtDNA as the Ice Man.
“Apparently,” Rollo adds, “this group is currently extinct. We do not yet know whether it has disappeared completely or just become extremely rare."
In honor of the first identified owner of such an mtDNA, the researchers named this branch of the human family tree “Otzi Branch,” K1o.
Since the mutations in question do not affect the functioning of the organism in any way - the proteins that are produced by them do not differ in any way from the “non-mutated” ones - and their frequency is approximately known, one can even estimate the age of K1o. According to the co-author of the work, Martin Richards, the "foremother" of the Otzi clan, in which the mutations transmitted through the female line to the "Ice Man" appeared, lived about 20 thousand years ago. However, this ancient lineage was interrupted - or became very rare.
By the way, the mutations characteristic of the "Otzi line" - just not all at once - scientists have found in the genetic database of 11 more people. Six of them live in Austria and Germany, and one even in Russia. True, for the relationship with Otzi, our compatriot, like the other ten candidates, lacks several other nucleotide substitutions.
It's still impossible to say with confidence that Otzi did not have descendants.
Research on the mummy
According to radiocarbon analysis, Otzi lived from 5,100 to 5,350 years ago. Analysis of pollen, dust particles and isotopic composition of tooth enamel showed that he was born in the area of a modern Italian village …
He could not transfer his mtDNA to them - it is inherited only through the maternal line. Another thing is that none of his closest relatives left offspring that would survive to this day in any noticeable quantity. However, now more and more people are sequencing their DNA, so it is possible that at some point somewhere the owner or possessor of the mitochondrial genetic code identical to Otzi will emerge.
The chance to find a living descendant of Otzi himself is not lost either. To do this, scientists need to decode the nuclear DNA contained in the Otzi Y chromosome, which is transmitted through the male line. But it is thousands of times more complex than mtDNA and tens of times more complex than those “paleochromosomes” that have been deciphered so far - for example, fragments of nuclear DNA from a Neanderthal. However, Otzi's body has been preserved much better for 5 thousand years than the bones of Neanderthals for 30 thousand years, so this option is not excluded.
Otzi might not have had offspring at all. A couple of years ago, the same Franco Rollo suggested that the "Tyrolean shaman" could well be a lonely outcast. In his opinion, mutations in two of the Ice Man's mtDNA regions deciphered at that time are usually associated with reduced sperm motility and may indicate Otzi's inability to reproduce. However, this time Rollo claims that none of the 30 differences of Otzi's mtDNA from the standard has been proven to be associated with any congenital anomalies.
