(Reuters) – Ancient DNA analysis transforms understanding of the genetic ancestry of modern Japan’s population, identifying a crucial contribution of people who arrived around 1,700 years ago and helped revolutionize Japanese culture.
Research published on Friday showed that the Japanese people carry the genetic signatures of three ancient populations rather than just two as previously thought – a more complex ancestry for the archipelago nation of about 125 million.
The researchers analyzed the genetic information of 17 ancient Japanese people – DNA extracted from the bones of 12 specifically for this study and five previously – and compared it to the genomic data of modern Japanese.
Previously documented genetic contributions have been confirmed by two ancient groups. The first was the indigenous hunter-gatherer culture of Japan dating back to around 15,000 years ago, the beginning of the so-called Jomon period. The second was a population of Northeast Asian descent who arrived around 900 BC, bringing in the cultivation of wet rice during the following Yayoi period.
Modern Japanese have about 13% and 16% of genetic ancestry from these two groups, respectively, the researchers determined.
But 71% of their ancestors were from an ancient third population of East Asian descent who arrived around 300 AD to initiate what is known as the Kofun period, bringing various cultural advances and developing centralized leadership. These migrants appear to have ancestors resembling mainly the Han people who make up the bulk of the Chinese population.
“We are very excited about our findings on the tripartite structure of the Japanese populations. This discovery is important in terms of rewriting the origins of modern Japanese by harnessing the power of ancient genomics, ”said geneticist Shigeki Nakagome of Trinity College Dublin in Ireland. , co-leader of the study published in the journal Science Advances.
The research demonstrates the ability of ancient DNA to discover new ancestral components that could not be seen using modern genetic data, added Daniel Bradley, co-director of the study, also from Trinity College Dublin.
The study showed that people from the ancient cultural phases of the foraging, agriculture and state formation of the state of Japan each made a significant contribution to the ancestry of today’s Japanese population. hui, Nakagome said.
The oldest of the skeletons from which DNA was extracted was a female dating from around 9,000 years ago from a Jomon period site in Ehime Prefecture, while the most recent were three skeletons dating from around 1 500 years from a Kofun period site in Ishikawa Prefecture, according to geneticist and study co-leader Takashi Gakuhari from Kanazawa University in Japan.
The Kofun period takes its name from the large earthen tombs built for members of the new ruling class at a time of importing technology and culture from China via the Korean peninsula.
“Chinese characters began to be used around this time, such as Chinese characters inscribed on metal tools, such as swords,” Nakagome said.
Insularity was a by-product of Japan’s island geography, surrounded by oceans that made migration difficult in ancient times. The first people to reach Japan arrived over 30,000 years ago at a time when sea levels were lower, when there may have been a land bridge to the Asian mainland.
The researchers also said that the genetics of the Japanese population have remained largely stable since the Kofun period, which lasted around 300-700 AD.
(Report by Will Dunham in Washington, edited by Rosalba O’Brien)