- Trinity College Dublin experts sequence 12 ancient Japanese genomes
- They found evidence of a second, later arrival of genetic material from East Asia
- This he dated to the Kofun period (300–700 AD), a time of political change.
- It was thought that an influx occurred about 16,000 years ago
Modern Japanese populations are descended from three ancient cultures – instead of just two, as previously thought – a new genetic analysis has determined.
While the Japanese archipelago has been occupied by humans for at least 38,000 years, Japan has only changed rapidly in the last 3,000 years.
These saw a shift from fodder cultivation to wet-rice cultivation and the development of a technologically advanced imperial state.
It was thought that today’s Japanese populations derive their ancestry from indigenous Jmon hunter-gatherer-fishers and later Yayoi farmers.
While the Jomon occupied the archipelago around 16,000–3,000 years ago, the Yayoi migrated from the Asian continent to live in Japan from 900 BC to 300 AD.
Researchers led by Trinity College Dublin studied 12 ancient genomes sequenced from the bones of people who lived before and after the farming period.
This revealed a second, later influx of East Asian dynasty during the imperial Kofun period from AD 300–710, when political centralization emerged in Japan.
The team notes that these findings are supported by several lines of archaeological evidence for the introduction of new, larger settlements in Japan in this period.
Modern Japanese populations are descended from three ancient cultures – instead of just two, as previously thought – a new genetic analysis has determined. Image: One of the ancient Japanese skulls from which DNA was extracted
While the Japanese archipelago has been occupied by humans for at least 38,000 years, Japan has only changed rapidly in the last 3,000 years. Image: An early Jomon skeleton – from which the genetic material was sampled – from the Odek shell midden
compared to agricultural
According to the team, the advent of agriculture is generally associated with population replacement.
This is the case for the Neolithic transition across Europe, with only minimal contributions seen from hunter-gatherer populations.
However, the researcher’s genetic evidence indicates that this was not the case in Japan.
Instead of replacement, the switch to farming saw a process of assimilation between the indigenous Jomon and the visiting Yayoi wet-rice farmers.
Lead paper author Shigeki Nakagome of Trinity College Dublin explained, ‘Researchers are learning more and more about the cultures of the Jmon, Yayoi and Kofun periods as more and more ancient artifacts appear.
‘But prior to our research we knew relatively little about the genetic origins and effects of agricultural transition and later the state-forming phase.
‘We now know that ancestors derived from each of the foraging, agricultural and state-building phases contributed significantly to the formation of the Japanese population today.
‘In short, we have an entirely new tripartite model of Japanese genomic origin – instead of the dual lineage model that has held up for a significant time.’
The team’s analysis also determined that the Jomon maintained a small population size of about 1,000 people over several millennia, who diverged from continental populations around 20,000–15,000 years ago.
Japan became increasingly more isolated in this period as sea levels rose—removing ties to the forged Korean Peninsula about 28,000 years ago at the beginning of the Last Glacial Maximum.
The widening of the Korea Strait 16,000–17,000 years ago coincides with the earliest evidence of Jomon pottery production.
Niall Cook, a population geneticist at Trinity, said: ‘The indigenous Jomon people within Japan had their own unique lifestyle and culture for thousands of years before adopting rice cultivation in the later Yayoi period.
‘Our analysis clearly finds them to be a genetically distinct population with unusually high affinity among all sampled individuals—even those that differ in age by thousands of years and on different islands. on excavation sites.
‘These results strongly suggest a long period of isolation from the rest of the continent,’ he explained.
The widening of the Korea Strait 16,000–17,000 years ago coincides with the earliest evidence of Jomon pottery production, examples of which are painted
“We now know that ancestors derived from each of the foraging, agricultural and state-building phases contributed significantly to the formation of the Japanese population today,” Professor Nakagome said. Image: The Kamikuroiwa rock shelter in Shikoku’s Ehime Prefecture, from which the oldest Jmon individual was sequenced, was unearthed
“The Japanese archipelago is a particularly interesting part of the world to investigate using a time series of ancient samples,” said paper author and population geneticist Dan Bradley of Trinity College Dublin.
The reason for this, he explained, is Japan’s ‘extraordinary prehistory of long-term continuity and the rapid cultural change that followed’.
‘Our insights into the complex origins of modern Japanese once again demonstrate the power of ancient genomics to uncover new information about human prehistory that could not have been observed otherwise.’ He concluded.
The full findings of the study were published in the journal science progress.
Researchers led by Trinity College Dublin sequenced 12 ancient genomes extracted from the bones of people who lived before and after the farming period across Japan.
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