Researchers from Hacettepe University and Middle East Technical University (METU) analyzed via ancient genomes the traces of human migrations through Anatolia, an intercontinental bridge, and they published their results in Current Biology.
The team of geneticists, anthropologists and archaeologists studied how human mobility in Southwest Asia and the Eastern Mediterranean changed over the past 10,000 years (since the advent of agriculture) through an analysis of ancient genomes. They produced 35 novel ancient genomes from modern day Anatolia, Greece, Georgia, Azerbaijan and Iran. The oldest genomes from Anatolia came from Musular (Aksaray), a site located in Cappadocia that is dated to 9,000 BP. Besides Musular, genome data belonging to a total of 10 individuals from the Bronze Age and Hellenistic, Roman and Ottoman periods were produced from historical settlements such as Ulucak (İzmir), Çine-Tepecik (Aydın), Boğazköy/Hattuşa (Çorum) and Gordion (Ankara). These new data provided a better understanding of Anatolia’s past genetic diversity.
How did genetic diversity in Anatolia change in the last 10,000 years?
Upon analyzing the data, the researchers observed that genetic diversity in Anatolia has continuously increased over the last 10,000 years. This change was attributed to the fact that communities with different genetic backgrounds came to Anatolia over the course of the time and mixed with the locals, which in turn suggests that the region received continuous immigration in the past, as it does today. The team observed a similar pattern for Greece, Iran, the South Caucasus and the Levant: genetic diversity constantly increased in these regions as they also received migration in the same way.
A more detailed analysis revealed that in the Neolithic period and immediately afterwards (between 10,000 and 6,000 BP) genetic admixture mainly took place within Southwest Asia and the eastern Mediterranean. The researchers observed that Anatolia received migration from the Caucasus, Iran and the Levant, and was also a source of migration towards Greece, the Caucasus, Iran and the Levant. The authors construed from this result that, in different regions of Southwest Asia agriculture developed independently from each other, and that regional populations admixed among themselves.
"In addition to confirming the existing knowledge that human mobility increased with agriculture, the study also provided new findings about how the patterns of this mobility changed over time,” said Dilek Koptekin, the first author of the article. “Whereas most of the mobility took place within Southwest Asia in the first half of the Holocene, immigrants from more distant regions came to this region in the last 6,000 years, with the advent of the Bronze Age.”
Koptekin, who completed her doctorate at the Graduate School of Informatics, METU this year, stated that they termed this as the “expanding mobility model” and said, “There must be various technological and social reasons behind this increase in mobility between distant regions. Four thousand years ago horses were domesticated, wheels were introduced, and new seafaring methods were developed. This must have facilitated long-distance human mobility. Furthermore, trade routes were established between distant regions. The establishment of states and armies may also have promoted wide-range mobility.”
Ezgi Altınışık, who lectures at Hacettepe University Department of Anthropology and is among the authors of the study, cited the contribution of Central Asia to the gene pool of Anatolia in the last millennium as an example of this type of large-scale mobility. According to the findings of a genetic study published last year in PNAS, approximately 10 percent of the ancestors of present-day Anatolian people were Turkic groups who migrated from Central Asia.
According to Hacettepe University Anthropology Department lecturer Füsun Özer, who was an advisor to the study, ancient DNA findings show that it was common for immigrants to admix with locals in other regions as well as in Anatolia, and that continuity is dominant in the history of communities. “In most cases of migration, those who migrated to a region from outside did not cause a decrease or an extinction of the local population, but rather mixed with them” said Özer. “It is rare for the natives of a region to disappear following a migration. In fact, there is yet no clear indication of such an example in the last 10,000 years of Anatolia. Migration and admixture continued unabated, speeding up or slowing down from time to time, resulting in a continual increase in genetic diversity.”
"I think our newest finding relates to the relationship between human mobility and gender roles," said Mehmet Somel from METU Department of Biological Sciences, who also served as an advisor to the study. He noted that, concerning the mobility observed in the last 10,000 thousand years, a relative increase in male contribution was observed while the female contribution decreased. According to Somel, these findings can be interpreted as either an increase in the role of men in migration processes or a decrease in the role of women. “We do not know whether this is due to wars, trade with distant regions or other migration processes. Our results imply that in the last few thousand years gender roles in human mobility started to differ in parallel to the development of social classes and increase in hierarchies. It goes without saying that this also reminds us that we were not always how we are today.”
The study was supported by various research funds from Scientific and Technological Research Council of Turkey (TÜBİTAK) and the European Research Council (ERC), and conducted by a team of 55 scientists from various countries such as Sweden, Greece, Georgia, Azerbaijan, Germany and the USA, under the leadership of the Ankara team.