Prehistoric Migration from China to Americas Discovered in Recent Study

As the last continents to be settled by humans, the question of how and when people first came to the Americas has long intrigued scientists.

A new genetic study published Tuesday in Cell Reports finds that some of the first arrivals came from China during two different migrations: the first during the last ice age, and the second shortly after.

“Our findings indicate that besides the ancestral sources of Native Americans in Siberia, the northern coast of China also served as a genetic repository contributing to the gene pool,” Yu Chun-Li, one of the report’s authors, told AFP.

Lee added that during the second migration, the same lineage of people settled in Japan, which may help explain the similarities in prehistoric arrowheads and spears found in the Americas, China, and Japan.

It was once believed that the ancient Siberians, who crossed a land bridge that once existed in the Bering Strait connecting modern Russia and Alaska, were the only ancestors of the Native Americans.

Recent research has indicated, from the late 2000s onwards, that more diverse sources from Asia can be linked to an ancient lineage responsible for creating populations across the Americas, including Bolivia, Brazil, Chile, Ecuador, Mexico, and California.

Known as D4h, this strain is found in mitochondrial DNA, which is inherited only from mothers and is used to trace maternal ancestry.

A team from the Kunming Institute of Zoology has embarked on a ten-year search for D4h, combing 100,000 modern and 15,000 ancient DNA samples across Eurasia. They eventually came to 216 contemporary individuals and 39 ancient individuals who came from the ancient lineage.

By analyzing mutations that accumulated over time, looking at the geographic locations of the samples and using carbon dating, they were able to reconstruct the origins of the D4h strain and its expansion history.

The results revealed two migration events. The first was between 19,500 and 26,000 years ago during the last Ice Age Maximum, when ice sheet coverage was at its peak and climatic conditions in northern China were likely unfavorable.

The second occurred during the melt period, between 19,000 and 11,500 years ago. An increase in the population during this period may lead to the occurrence of migrations.

coastal migration

Either way, scientists believe the travelers were sailors who docked in America and traveled along the Pacific coast by boat. This is because a grassy passage between two ice sheets in modern Canada, known as the “Ice-Free Inner Corridor”, has not yet been opened.

In the second migration, a sub-group diverged from coastal northern China into Japan, contributing to the Japanese people, especially the indigenous Ainu, the study said, a finding consistent with archaeological similarities between ancient peoples in the Americas, China and Japan.

The strength of the study, Li said, is the number of samples they unearthed, and the supplementary evidence from Y-chromosome DNA showing that Native American ancestors lived in northern China at the same time as female ancestors made them confident in their findings.

“However, we do not know in which specific place in the northern coast of China this expansion occurred and what specific events encouraged these migrations,” he said.

“More evidence, especially ancient genomes, is needed to answer these questions.”

© 2023 AFP