From the cave, researchers recovered a hominin skull cap that looked unusual. It has characteristics of both modern humans and archaic humans according to previous physical anthropological studies. For example, the shape of the skull and teeth resembled characteristics of Neanderthals, and the brain appeared to be smaller than that of modern humans. Some researchers had thought the skull probably belongs to an unknown archaic human species that lived until fairly recently, a hybrid population of archaic and modern humans, or the retention of a large number of ancestral polymorphisms in Paleolithic anatomically modern humans (AMHs).  

In a study published in Current Biology, researchers led by Prof. SU Bing from Kunming Institute of Zoology of the Chinese Academy of Sciences sequenced the first genome of ancient human fossils dated to the Late Pleistocene, which was unearthed at Maludong, and suggested that the mysterious hominin “Mengzi Ren” (MZR) belongs to an extinct maternal branch of modern humans instead of an archaic human species previously proposed by some researchers, and she possessed deep ancestry that might have contributed to the origin of the First Americans.

Given the warm and humid paleoenvironment at low latitude areas such as Yunnan, to recover ancient DNA from MZR was a challenging task. Genomic sequencing showed that the skull is a female. Although she has an unusual morphological characteristics, researchers found that she belongs to an extinct maternal lineage of modern humans whose surviving decedents are now majorly found in the Himalayan region and Southeast Asia.   

Besides, researchers showed that during the Late Pleistocene, human populations living in southern East Asia had rich genetic and morphologic diversity, the degree of which is greater than that in northern East Asia during the same period. “The finding suggests that early humans who first arrived in eastern Asia had first settled in the south, before some of them moved to the north, which is an important piece of evidence for understanding early human migration,” SU Bing said.

In addition, researchers compared the MZR genome with that of people from around the world. They found that she was linked deeply to the East Asian than to the Hòabìnhìans (from Southeast Asia), Jomons (from Japan), the Paleo-Siberians (beyond 20 kya) and Tianyuan (from Zhoukoudian). Based on this pattern of genetic affinity, they inferred that ~16,000 to 14,000 years ago, from Maludong in the south to the Amur region in the north, the broad Late Pleistocene East Asians already formed an ancestral clade that directly contributed to the First Americans.  

These new data combined with previous research data proposed that some of the southern East Asian people had migrated northward along the coastline of nowadays eastern China, by way of Japan, reaching Siberia, and eventually crossed the Bering Strait between the continents of Asia and North America, and became the first group of people arrived in the New World.    

By looking at the spatial-temporal distribution of an East Asian specific sequence variant which causes skin lightening in current East Asian population. Researchers found that this variant first appeared in the southern coastal region of China during the early Holocene (~7.5 kya), and it quickly elevated to high frequencies in northern populations due to natural selection on skin pigmentation.   

In the future, researchers plan to sequence more ancient human DNA using fossils from southern East Asia, especially ones that predated the Maludong people in order to elaborate the migratory and diversity patterns of early modern humans in eastern Asia.  

“Such data will not only help us paint a more complete picture of how our ancestors migrate, but also contains important information about how humans change their physical appearance by adapting to local environments overtime, such as the variations in skin color in response to changes in sunlight exposure,” said SU.