Analysis of the article “Ancient DNA indicates human population shifts and admixture in northern and southern China”

The results can be seen in the three maps of the figure showing that the ancestry localized to the north and south in the Early Neolithic isfound in admixed form across northern and southern East Asia today. These maps are the heatmaps showing f4dated to the Early Neolithic, Late Neolithic and present day.Then researchers developed mixture models (they are illustrated by three figures — ancestry proportions estimated for Neolithic and present-dayindividuals) to evaluate ancestry proportions in Neolithic populations, where Neolithic northern and southern East Asians each belong to a certain ancestry associated with their location in northern or southern East Asia. In contrast, patterns observed in presentday East Asians show that the major factor reducing genetic differentiation in presentday East Asians is increased northern East Asian-related ancestry in southern East Asia.During the Neolithic,there was a division between East Asians north and south of the Qinling-Huaiheline in ancestry; but in the present day, ancestriespreviously localized to only northern or southern East Asia can be found inappreciable frequencies in both regions. The authors assume that lack of Paleosiberian-related ancestry in the peripheral edges of East Asia suggests that different types of gene flow from north to south occurred in East Asia.Also was investigated whether the northern East Asian affinity is closer to inland or coastal northern East Asians. The study suggests that the northern East Asian ancestry found in all present-day mainland East Asians is primarily related to populations along the lower reaches of the Yellow River. These observations are consistent with archaeological and historical studies that argue for an origin of the Han ethnic group in northern China, along the Yellow River.The next chapter of the article is titled as “Proto-Austronesian origins in southern China and coastal connections”. Austronesian-speaking populations extend from Taiwan to the Southwest Pacific and to Madagascar. The exploration data maintain a proto-Austronesian origin in mainland southern China.These results were obtained by genetic modeling with mitochondrial DNA genomes. The authors also found therelation to present-day Austronesians extending across all Neolithic samples tested from mainland southern China and Taiwan Strait islands that maintain a coastal southern China origin for proto-Austronesians.Nextwere investigated relations between the ancient samples and 3000-year-old Southwest Pacific Islanders (from Vanuatu), who share a close relationship to present-day Austronesians. Further results confirmed the proposed relation between Neolithic southern East Asians and proto-Austronesians. The researchers tell that a lack of genetic isolation between coastal populations can be observed all along the coast of East and Southeast Asia.And finally, the authors conclude that the patterns demonstrated in survey indicate that coastal regions were areas of interconnectivity and gene flow rather than of isolation. These affinities between populations along the eastern coast of Asia (and island populations off the coast) that are not shared by more-inland Asian populations suggest that interactions along marine-related environments played an important role in the prehistory of coastal Asia.After all there is a part of discussion, which summarizes the results and provides the main conclusions of the research.The most important points are presented below.The genetic survey of Neolithic northern and southern East Asians shows population differentiation during the Early Neolithic to an extent not observed in present-day East Asians.The evidence of a first layer population in coastal southern East Asia by 8400 years ago was not found in this research. But was noticed increased northern influences in southern East Asia between the Early Neolithic and today. Thereby the reason for the spread of a second layer associated with northern East Asian ancestry is still an important model to investigate in the context of East Asian prehistory.The spread of northern East Asian ancestry led to increased admixture in both directions, such that most of today’s East Asians are a mixture of northern and southern East Asian ancestries. Thus, not only was there spread of northern East Asian ancestry into southern East Asia, but southern East Asian–related ancestry can be found in some present-day northern East Asians.Much of the human movement that contributed to present-day East Asian genetic patterns must have occurred after the Neolithic.Shared ancestry amongst ancient individuals on the southeast coast of mainland East Asia, islands in the Taiwan Strait, and the Southwest Pacific island Vanuatu suggests that the Austronesian expansion derived from a population that came from southern China.Gene flow among coastal populations in East Asia is a common trend, as different coastal connections can be observed in Neolithic populations from as far north as coastal Siberia and the Japanese archipelago to as far south as coastal Vietnam.In individuals from northern and southern China dating to 9500 to 300 cal yr B.P., a close genetic relationship is observed between East Asians, althoughwith shifts in ancestry indicative of population movement and admixture during the Neolithic.The authors suggested that increased genetic sampling from the Paleolithic and from populations further inland in central China should help to further clarify the relationships among Paleolithic hunter-gatherers, Neolithic farmers, and present-day populations of East Asia.The article has 32 sources in references and notes that are given after the discussion. To my opinion, this article is very interesting and informative and I would like to follow the continuation of this research.I would strongly recommend reading this article to everyone interested in the human genetic evolution, the history and population of China.