Hepatitis B Virus and Genghis Khan

The man who conquered almost the entire known world was originally called Temujin. It means 'of iron' in Mongolian and is derived ultimately from the old Turkish word temür ('iron'). We know him Genghis Khan(c. 1162-1227), the Mongol warrior who started life as a nomad in Mongolia. Later, his armies swept across the Asian steppes, conquering all they encountered. Only his timely death as a frail and sickly 65-year old Genghis Khan could arrest the hordes from reaching Europe.
Now, scientists found evidence that Mongol warriors from the steppe carried an early form of Hepatitis B Virus. Sequencing 304 genomes from the skeletons of people who lived on the steppe during the Iron and Bronze Ages (from about 2500 BC until 1200 AD), they found that twenty-five of the samples had DNA from Hepatitis B Virus in their bones[1].

That means that Hepatitis B Virus on the ancient steppes may have been as prevalent as it is in some of the most heavily impacted areas of the world today.
What the researchers found was that Hepatitis B Virus was circulating on the Eurasian steppes for thousands of years. One of the stains found is now extinct, having apparently faded out of existence sometime in the last 4,500 years. And one of the nine major genotypes circulating today appears to be the product of an ancient recombination between two strains of the Hepatitis B Virus.
[Novel genotypes A, B, C, D, E, F, G, H]
[Genotypes of Bronze Age and Iron Age]
Most of the genetic diversity in Hepatitis B viruses today probably arose sometime between 25,000 and 13,400 years ago, when the genetic lineages of Old World Hepatitis B strains and New World Hepatitis B strains split.

One modern strain, genotype A, was previously thought to have emerged in Africa and spread to the Americas and India within the last few centuries via the slave trade. But the researchers found some ancestral strains of type A in people living on the steppe as early as 4,300 years ago: some from the Sintasha culture in what is now southwest Russia, and one in a person from the Scythian culture in what is now Hungary.

That, suggests that it's the other way around, that it came from Europe, but it was introduced to South Asian populations historically recently.

[1] Mühlemann et al: Ancient hepatitis B viruses from the Bronze Age to the Medieval period in Nature – 2018

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