For sixty years, scientists believed Japanese people came from two main ancestral groups: the ancient Jomon hunter-gatherers who lived on the islands for thousands of years, and rice farmers who arrived from the continent. Now, new genetic research has discovered a third ancestral lineage that nobody had seen before.
Researchers at RIKEN's Center for Integrative Medical Sciences studied the complete genomes of over 3,200 people from seven regions across Japan. Their findings, published in Science Advances, revealed this hidden third strand of ancestry comes from northeastern Asia. It is strongest in northeastern Japan and becomes weaker as you move west.
Scientists believe this third ancestry may trace back to the Emishi, an ancient people described in old Japanese chronicles who lived in the forests of Tohoku. For generations, what happened to their descendants was unknown. Now, their genetic signature appears in the DNA of modern Japanese people.
The study also discovered something important for medicine. Researchers identified DNA segments inherited from Neanderthals and Denisovans that are still active in modern Japanese genomes. Some of these ancient variants are linked to diseases like coronary artery disease, type 2 diabetes, and rheumatoid arthritis. One variant even affects how patients respond to semaglutide, a modern diabetes medication.
This new research shows that the story of Japanese ancestry is more complex than previously thought. It reveals how ancient human movements shaped the genetics of modern populations.