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Chinese fossils point to a surprising link between East Asia and early Americas

DNA from fossils found in Southern China point toward the presence of East Asian ancestry in Native American populations.

(CN) — Researchers at the Chinese Academy of Sciences (CAS) have sequenced the genome of a Late Pleistocene human, revealing a connection beyond East Asia that may shed light on human migration and population patterns in the early days of our development.

The studied genome was sourced from a fossil found at Malu Dong, or Red Deer Cave, in the Yunnan province in southern China. The fossil was determined to have come from the Late Pleistocene, around 14,000 years ago, and is the first genome sequenced from this era in southern East Asia. Although Yunnan’s environment makes fossil preservation difficult, there was enough genetic material for scientists to extract DNA from the fossil skull cap.

“The Red Dear Cave site unearthed an important human remains, which based on morphological studies, were proposed as an archaic human species like Neanderthal or a mix between archaic human and modern human. To test this hypothesis, we conducted ancient DNA (aDNA) analyses, and proved that MZR is in fact a female modern human,” said Bing Su, a researcher at CAS and an author of the study published Thursday in the journal Current Biology.

The genetic sample from this anatomically modern human, dubbed Mengzi Ren (MZR), for the county in which she was found, allowed scientists to investigate her affiliation with modern human populations.

The presence of MZR first indicated a rich diversity of human populations in East Asia during the Late Pleistocene. The study notes an “obvious stratification and substructure of ancient human populations between southern China and mainland Southeast Asia, an indication of already diversified genetic backgrounds of the Late Pleistocene populations in southern East Asia.”

The team of researchers, comprised of Su, along with co-authors Xueping Ji, an anthropologist, and Xiaoming Zhang, a geneticist and all of the Kunming Institute of Zoology at CAS, compared the fossil’s genome to that of people around the world. This comparison would find that modern distinctions between populations are complicated by the further back we are able to trace early human lineage.

In our modern understanding, it may seem that the entire gamut of East Asian and Southeast Asian populations must have evolved closely with each other. However, the study determined that this new genome is actually quite distinct from previously studied genomes of northern East Asian populations, as it shares more alleles with the genomes of both Southeast Asians and other ancient populations in roughly the same time period. This discovery indicates that northern-southern populations in modern day East Asia may have evolved very differently and from different sources.

On the other hand, it is hard to imagine that there is any connection at all between the East Asians and Native Americans, but the study’s most significant finding emerged upon comparing the genome to Native American populations.

“In fact, there have been many evidence, mostly genetic evidence, pinpointing the East Asian contribution to the peopling of the New World, though this likely occurred about 12,000 years ago when the land bridge at the Bering Strait was present,” Su said in an email interview. “The previous studies were mostly based on the genetic data of current populations. By contrast, aDNA data can provide genetic data of the historic time.”

Su and his team discovered a closer relationship between MZR’s genome to Native American populations than even to northern East Asian populations, indicating that East Asian contribution to Early American populations developed prior even to northern-southern East Asian divergence and that early humans may have initially settled first in the south before migrating either to the north or across the Bering Strait to the Americas.

“Based on our data, we proposed that there might be a coastal migratory route along the coastal line of East Asia continent during Late Pleistocene, by way of Japan, reaching northeastern Siberia, and eventually crossed the Bering Strait, leading to the peopling of the New World,” Su explains.

This theory corresponds to archeological and anthropological information of the Late Pleistocene. In finding East Asian ancestry in the origins of Native Americans, researchers can use reconstructions of ancient migration patterns to develop a deeper understanding of early human development.

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