NEW YORK – Members of an ancient Gaya Kingdom found in Korea during the Three Kingdoms period appear to have shared ancestry with a population resembling the Jomon population in Japan, according to a new study by investigators in Austria, South Korea, Portugal, and the US, who sequenced eight samples from South Korea dated at around 1,700 years old.
"[W]e report the first paleogenomic data from the Korean Three Kingdoms period, a crucial point in the cultural and historic formation of Korea," first and corresponding author Pere Gelabert, an evolutionary anthropology and human evolution and archeological sciences researcher at the University of Vienna, and his colleagues wrote in Current Biology on Tuesday.
The Three Kingdoms period was marked by "extensive development of iron technology and trade with neighboring populations," they explained, and the Gaya Confederacy "had the most developed iron production and trading infrastructure during the early Korean [Three Kingdoms] period, which included the exchange of goods and possibly also the movement of people … of the Japanese archipelago and northern China."
Using shotgun sequencing, the researchers generated genome sequence data ranging in depth from 0.7-fold to more than 6-fold average coverage for eight ancient samples dated to the 4th or 5th century, including seven samples from an archeological site dubbed Daeseong-dong in Gimhae City, a funerary site used by members of the Gaya Confederacy, and a lone sample from a more "Yuha-ri" shell mound, which came from a child buried at the more modest burial site.
The sample set had been whittled down from 27 petrous bone or tooth samples tested at the two sites with DNA screening, they noted.
Analyzing the ancient sequences together with almost 2,300 available genome sequences or genotypes from other ancient and modern-day individuals in the region revealed a combination of Bronze Age ancestry from northern China and ancestry from a Jomon-related population, the researchers reported, consistent with genetic studies on contemporary Korean populations, which point to past admixture that included populations from parts of China and Japan.
"The observed substructure and proportion of Jomon-related ancestry suggest the presence of two genetic groups within the population and diversity among the Gaya population," the authors wrote, noting that they did not see ties between individuals' genetics and their sex or apparent social status, gauged by the way they were buried.
The team saw signs that the Korean population has remained relatively stable over time, maintaining features similar to those found in the ancient individuals profiled from the Three Kingdoms period. Those similarities extended to estimated physical features, which were predicted for the ancient individuals based on SNPs linked to facial features, hair color, eye color, susceptibility to nearsightedness, baldness, alopecia, and other traits.
The authors noted that more extensive paleogenomic studies will be needed to pinpoint the sources of the northern China- and Jomon-related ancestries found in Korea, as well as the distribution and proportions of ancestry in different parts of the Korean peninsula.
"In the near future, larger sample sizes and more advanced informatic tools based on individual genetic histories may allow us to differentiate between these similar populations to uncover the origin of this ancestry," they concluded.