Level 1 — Absolute Beginner

Scientists in Japan have new news. They studied the DNA of more than 3,000 Japanese people. DNA is the code inside our cells.

Before, people thought modern Japanese came from two old groups: the Jomon and farmers from East Asia.

Now, scientists say there is a third group. This group lived in the north of Japan. Their name is the Emishi.

The study also found small parts of DNA from very old people called Denisovans and Neanderthals. They lived a long, long time ago.

scientist

a person who studies how nature and the world work

DNA

the code inside cells that tells the body how to grow

cell

the smallest part of any living thing

modern

from today's time

old

from many years ago

group

a number of people together

north

the direction opposite of south

study

to learn about something carefully

Level 2 — Elementary

Scientists have found a hidden third ancestral group in the DNA of modern Japanese people. The study was published in the journal Science Advances on Thursday, May 14.

Researchers analysed the whole genomes of 3,256 people from across Japan. They built a new database called JEWEL — short for Japanese Encyclopedia of Whole-Genome/Exome Sequencing Library.

Until now, scientists thought today's Japanese came from two ancient groups: the Jomon hunter-gatherers and rice farmers who arrived from continental East Asia. The new study adds a third group, probably linked to the ancient Emishi people of northeastern Japan.

The team also identified 44 small regions of archaic DNA from Denisovans and Neanderthals. One Denisovan region inside a gene called NKX6-1 is linked to type 2 diabetes and may change how some patients respond to the drug semaglutide.

ancestral

relating to ancestors — the people who lived long before us

genome

the complete set of DNA in a living thing

database

an organised collection of information stored in a computer

hunter-gatherer

an early human who lived by hunting and collecting wild food

continental

relating to a continent, especially the main landmass of Asia or Europe

archaic

very old; from an extinct human group such as Denisovans or Neanderthals

diabetes

a disease in which the body cannot properly control sugar in the blood

semaglutide

a medicine used to treat type 2 diabetes and obesity

Level 3 — Intermediate

A landmark population-genetics study published on Thursday in Science Advances has dismantled the long-standing 'dual-structure' model of Japanese ancestry, replacing it with a tripartite picture in which a previously unrecognised population — most likely the ancient Emishi of northeastern Honshu — joins the well-documented Jomon hunter-gatherers and continental East Asian farmers as a third foundational ancestor of the modern Japanese.

The work, led by RIKEN, the University of Tokyo and Tohoku University, draws on a new resource called JEWEL — the Japanese Encyclopedia of Whole-Genome/Exome Sequencing Library — comprising 3,256 high-coverage genomes sampled across 47 prefectures. By layering modern sequence data over published ancient genomes from Hokkaido, Honshu and Okinawa, the authors triangulated three ancestry components whose proportions vary sharply by region: Jomon ancestry runs at 28.5 per cent in Okinawa but only 13.4 per cent in western Honshu, while East Asian farmer ancestry dominates in Kyushu and Kansai.

Perhaps the most surprising finding is the size and persistence of the third, Emishi-linked component, which is concentrated in Tohoku and northern Kanto. Historical records describe the Emishi as a population that resisted incorporation into the early Yamato state until the eighth and ninth centuries; the new genomic evidence suggests that their genetic contribution to modern populations has been substantially underestimated.

The study also catalogues 44 surviving regions of archaic introgression — DNA inherited from now-extinct hominins. A Denisovan-derived segment inside the NKX6-1 gene shows clear ties to type 2 diabetes risk and could affect responses to glucagon-like peptide-1 agonists such as semaglutide. Two further Neanderthal-derived regions cluster around immune-system loci that are unusually common in East Asians, hinting at past selective pressure from local pathogens.

tripartite

having three parts or involving three groups

dual-structure model

the older theory that Japanese ancestry comes from just two source populations

high-coverage genome

a genome sequenced many times so the data is very reliable

prefecture

an administrative region of Japan, similar to a state or province

triangulate

to use three sources or methods to pinpoint a result

introgression

the transfer of genes from one species or population into another by interbreeding

hominin

a member of the human family tree, including modern humans and extinct relatives

agonist

a drug that binds to a receptor and activates it, like semaglutide does for GLP-1

Level 4 — Advanced

The 'dual-structure' framework that has dominated Japanese population genetics for nearly four decades — a model in which present-day Japanese inheritance is parsed into Jomon hunter-gatherers and immigrant farmers of the Yayoi expansion — has received its most serious empirical challenge to date. A multi-institution Japanese team writing in Thursday's edition of Science Advances reports a third, statistically robust ancestry component, most plausibly identified with the ancient Emishi of northeastern Honshu, whose footprint had been systematically underweighted in earlier work.

The research is built on JEWEL (Japanese Encyclopedia of Whole-Genome/Exome Sequencing Library), a 3,256-individual high-coverage resource sampled across all 47 prefectures and curated by RIKEN with collaborators at the University of Tokyo and Tohoku University. By co-analysing JEWEL with previously published ancient genomes from the Funadomari Jomon site (Hokkaido), the Iwadeyama Tsuchimon site (Honshu) and Gusuku-period burials (Okinawa), the authors recover three latent ancestry vectors whose modern proportions vary along a clear north-east-to-south-west cline: Jomon ancestry peaks at 28.5 per cent in Okinawa and falls to 13.4 per cent in western Honshu; East Asian farmer ancestry dominates in Kyushu and Kansai; the residual Emishi-linked component is concentrated in Tohoku, northern Kanto and parts of Niigata.

Equally striking is the catalogue of 44 archaic introgression haplotypes still segregating in modern Japanese. A Denisovan-derived segment overlapping NKX6-1 — a transcription factor implicated in pancreatic β-cell differentiation — is significantly enriched in individuals with type 2 diabetes and associates with attenuated weight loss on glucagon-like peptide-1 receptor agonists such as semaglutide, hinting at archaic-modern pharmacogenomic interactions that could be relevant for precision-medicine dosing. Two Neanderthal-derived regions spanning HLA-DPB1 and TLR1/6/10 carry strong signatures of positive selection, consistent with adaptation to East Asian pathogen environments during the Holocene.

The findings have implications that go well beyond academic genomics. On historical questions, they offer a quantitative substrate for textual claims about Emishi distinctiveness in the Nihon Shoki and Engishiki; on biomedical questions, they argue forcefully that GWAS panels and polygenic-risk-score calibrations developed in European cohorts cannot be transplanted into Japanese clinical care without explicit corrections for the tripartite ancestry structure. The authors propose extending JEWEL to 100,000 individuals over the next four years and integrating ancient-DNA samples from the Okhotsk and Satsumon cultures to refine the Emishi signal further.

empirical

based on observation or experiment rather than theory

latent

hidden but present and detectable with the right method

cline

a gradient of biological or genetic change across a geographic area