Genomic history of the Golden Horde

[Music] Welcome to Science Sessions, the podcast of the proceedings of the National Academy of Sciences, where we connect you with Academy members, researchers, and policymakers. Join us as we explore the stories behind the science. I'm Paul Gabrielson. In Central Kazakhstan, or Nate Mazaliyems are set to hold the remains of elites of the Golden Horde, a Mongol Empire ruled by descendants of Genghis Khan. In a recent PNAS study, Aiken Askapuli of the University of Wisconsin-Madison and colleagues analyzed the genomes of four of these Golden Horde elites, particularly their paternal lineages as contained in the Y chromosomes of males. The results offer insights into the ancestry of the Golden Horde, as well as the modern populations that constitute their descendants. Aiken, can you introduce us to the Golden Horde? Golden Horde is the northwest extension of Mongol Empire, and the people of the Golden Horde was Kupchak speaking. They were a Turkic group, and the Kupchak language later became the language of the Golden Horde. The territory of the Golden Horde carved from the Erts River in the east to the Pontic Aspin step in the west, which is eastern Kazakhstan in the east to the modern day Ukraine in the west. It was a huge country. The Golden Horde was founded by the eldest son of Genghis Khan, Joshua, and then his male line descendants ruled this country. All known names like Batu, and Tokta Mersh, and Ablai Khan, and many figures of Golden Horde were success estates, all traits they are ancestry to Joshua, the eldest son of Genghis Khan. Tell us about the individuals in these Mausoleums, from whom you sample DNA. What do we know about them? These Mausoleums are located in central Kazakhstan, in the Lutol region. The Mausoleums are very spectacular, compared to other tombs in that region, and one of them is from the Mausoleum of Joshua Khan. By folklore, Kazakhs believe that the individual buried inside this Mausoleum is Joshua, the eldest son of Genghis Khan. Among the four individuals, one is female, and her name is Volganana, literally means Mausole and Volganana. Some historians postulated that she quote the daughter of the individual buried in the Joshua Khan Mausoleum. But when we did the genomic data analysis, our data did not support this claim. And then the second male was from the Mausoleum of Alashah Khan. We know little or nothing about his true identity. As a third Mausoleum, it is called Ayakkamur. It's literally meaning is "low-tune". We do not know who this person is. Genetic analysis identified that this individual is male and also potentially related to Joshua and Alashah Khan individuals. We could not confirm the personal identity of the individual who was buried in the Mausoleum of Joshua if he was actual eldest son of Genghis Khan or not, because we did not have a reference data in the future. If you have data from reliable true descendants of Genghis Khan or Genghis Khan himself, we can tell. But no, we cannot. And though we demonstrated that this individual came from the Mongolian placo, we still could not say anything about their personal identities. What did you learn about the modern populations the Golden Horde individuals were related to? First we analyzed the genomes of these individuals in comparison with the modern human populations across Asia and Europe, and we found that these Golden Horde individuals are more closely related to human populations in Siberia and the North East Asia. Such populations are relatively isolated and our genetic study pointed to the fact that these populations capture original genomic profiles. They are very close to our Golden Horde individuals. By a general profile, in contrast, we did not detect such a closed genetic relationship between these individuals and the modern casaks. There must be a genetic shift over the past several centuries. What did you learn about the Y chromosome characteristics of the Golden Horde? The Y chromosomes are transmitted from far to the signs, subgroups of Y chromosomes are called haplotypes. It can be understood as specific male lineage. We identified C3 stack cluster Y chromosomes from the males from these individuals. Over two decades ago, a group published a very interesting paper about genetic heritage of Mongols and they said that they found the signature haplogroup of Ginghsran. And we found the same haplogroup in these individuals. But when we did a comparative analysis, we noticed that the Y chromosome lineage which we found from these Golden Horde individuals belonged to a specific sub branch of C3 stack cluster. It is different from well known widely distributed C3 cluster types. What do these results say about the ancestry of the Golden Horde? The Golden Horde individuals traced the main genomic ancestry back to ancient Noseost Asians. The ancient Noseost Asians lived in the armor rib basin of Noseost Asia in the Neolithic period that was about 7000 years ago. The second populations that contributed to the genomic profiles of the Golden Horde individuals was the ancient Noseost Asians or burial cis-unrelated populations. How do these results help us understand population genetics in Central Eurasia? We could not find any Kazakh individual from modern Kazakhstan who is very closely related to these Golden Horde individuals by genomic profiles. Instead, these Golden Horde individuals are more closely related to Siberians and the Noseost Asians, modern day. Which means that this study is very important for understanding the overall genomic landscape and also dynamics in Central Eurasia. So how population movements and the mix help to shape the genomes of modern populations in this region, including Kazakhs and other populations. We found the specific C-3 star-class lineage, that is very rare in modern populations. Which means that during the time of Mongol Empire, they were already diversified C-3 star-class lineages. And some of them further expanded to form high frequency distribution in that region. But some, for some reason, did not expand. It is a new mystery, I think, so not all of them expanded into high frequency. Some of them did, some of them not. What are the caveats or limitations of the study? First thing is that we retrieve these voicromosome data from ancient archaeological samples. Ancient DNA is not high quality as modern DNA. When we generate data and then build the tree, the basal branches are quite robust, but the terminal branches leading to the branching of the individuals may not be so reliable. For example, the petal relationship among these three individuals. Which one is oldest or what are the actual relationship among these individuals? They are just very close, petal-related individuals or belong to the same petal lineage, which means that they may belong to the same clan, but not close related to each other. They do not have an ancestor-descendant relationship. We could not confirm this for 100%. There are some uncertainties. And then the second thing is that we just sample the four individuals. And the sample size may not be sufficient to generalize our findings to all individuals who belong to the ruling class of the Mongol Empire and the Golden Horde. We cannot generalize this to all individuals or within the Mongol Empire. Because like some of them may be from different populations like genomic background, we cannot say for sure that the ruling elite group should have a belong to the same population with the same genomic background. But this is not 100% sure because of the limit of the sample size. you get your podcasts. If you like this episode, please consider leaving a review and helping us spread the word.