Genghis Khan and the Y chromosome
Oxford University biochemist Chris Tyler-Smith, together with Mongolian, Uzbek, Chinese and Pakistani researchers, conducted a ten year long genetic study of 40 populations living in and around the territory of the former Mongol Empire. The researchers collected blood samples and analyzed DNA of the Y chromosome to learn about the genetic history of these populations.
We inherit our genetic characteristics from our parents, with each parent contributing half of the DNA which combines and forms a new genetic blend. However the Y-chromosome doesn’t recombine as other parts of the genome do, and apart from some mutations it passes from father to son intact. By identifying these mutations (known as markers) it’s possible to trace them to the point at which they first occurred and thereby establish the lineage of descent.
In Tyler-Smith’s study, 16 populations carried a star-cluster of Y chromosomes having the same genetic pattern, indicating a close relationship. These star-cluster chromosomes were also seen in the Hazara people of Pakistan and Afghanistan (who traditionally claimed Mongol descent), but otherwise were conspicuously absent in other populations outside the boundaries of the former Mongol empire.
Russian scientists, in another study, carried out a survey of Y chromosomes of 1437 men from 18 Asian ethnic groups and found that 35% Mongolians and 8.3% Altai Kazakhs carried the Genghis Khan Y chromosome. While the Mongols held eastern Russia for 250 years, there are few Y chromosome carriers there.
Now if the genetic spread had been by chance or by general population expansion, the star-cluster chromosomes would have shown up with variations in other populations elsewhere. Also, if the spread had been due to the presence of the chromosomes in the dominant group in the region, the Mongols, all modern Mongolians would have the star-cluster chromosomes. Neither of these premises hold true. So it’s likely that the chromosomes owe their spread to the activities of a single individual and his direct descendants.
The observed genetic mutations suggest that the most recent common ancestor (TMRCA) existed around 1000 years ago, and as the largest numbers of different star-cluster Y chromosomes were seen in Mongolia, this seems the likely place of origin of this remarkable lineage.
Tyler-Smith put forth the idea that the signature chromosomes probably belonged to the ruling Mongol house, originating from Genghis Khan’s great-great-grandfather, and that the establishment of the Mongol empire led to the spread.