The Dispersal and Back Migration of Y-Haplogroup DE in Southern Asia and Beyond

THE ANCIENT ORIGINS AND DISPERSALS OF Y HAPLOGROUP DE

Y haplogroup DE is a paternal genetic lineage that traces its origin to a common ancestor who lived in Asia around 65,000 years ago. This haplogroup is composed of two main branches: E and D, which have distinct geographic and demographic histories. In this blog post, we will explore the ancient origins and dispersal of y haplogroup DE and its descendants, based on the latest genetic and archaeological evidence.

THE OUT OF AFRICA MIGRATIONS AND DIVERSIFICATION OF DE

According to the most widely accepted model of human evolution, modern humans (Homo sapiens) originated in Africa and migrated out of the continent around 70,000 years ago, spreading across the world and replacing other hominin species such as Neanderthals and Denisovans. This migration is supported by both fossil and genetic data, and is reflected in the diversity of mitochondrial DNA (mtDNA) and Y-chromosome DNA (Y-DNA) haplogroups among different populations. mtDNA and Y-DNA are inherited maternally and paternally, respectively, and can be used to trace the maternal and paternal lineages of individuals and groups. mtDNA haplogroups are designated by letters from A to Z, while Y-DNA haplogroups are designated by letters and numbers, such as R1a1 or E-M96. Each haplogroup represents a branch of the human family tree, and can be further subdivided into subclades based on specific genetic markers or mutations.

The oldest mtDNA haplogroup is L, which is found exclusively in Africa and represents the maternal origin of all modern humans. The oldest Y-DNA haplogroup is A, which is also found mainly in Africa and represents the paternal origin of all modern humans. However, while mtDNA haplogroups diversified mainly within Africa, Y-DNA haplogroups diversified mainly outside of Africa, suggesting a different pattern of male and female migrations and interactions.

One of the earliest Y-DNA haplogroups to diverge from the African root is DE, which is estimated to have originated in Asia around 65,000 years ago, shortly after the out-of-Africa migration. DE is derived from an older haplogroup, CT, which is also the ancestor of other major Eurasian haplogroups, such as CF and K. DE is characterized by a mutation called M168, which is shared by all its descendants. DE split into two main branches: E and D, which are defined by mutations called M96 and M174, respectively. E is the most common haplogroup among African populations, while D is the most common haplogroup among some Asian populations, such as the Andamanese, Tibetans, and Japanese. The divergence of E and D is estimated to have occurred around 55,000 years ago, and reflects the different routes and destinations of the early DE carriers.

THE BACK MIGRATION OF E TO AFRICA AND EXPANSION OF D IN ASIA

E is the most widespread and diverse branch of DE, and is found in various regions of Africa, Europe, Asia, and Oceania. E is composed of several subclades, such as E-M2, E-M35, E-M78, and E-M123, which have different geographic and demographic histories. E is also the most common haplogroup among African Americans, due to the Atlantic slave trade that brought millions of Africans to the Americas. The origin and dispersal of E is a matter of debate among geneticists and anthropologists. Some researchers have argued that E originated in Africa and diversified there, while others have proposed that E originated in Eurasia and back-migrated to Africa. The latter hypothesis is based on the observation that E shares a common ancestor with D, which is mainly found in Asia, and that E shows a higher diversity and frequency in East Africa than in West Africa, suggesting a recent introduction from the east.

According to this hypothesis, after an initial out-of-Africa migration of early anatomically modern humans around 125,000 years ago, haplogroup DE diversified around the Himalayas and in or westward of Tibet, after which E-carrying males are proposed to have back-migrated from the paternal haplogroup's place of origin in Eurasia around 70,000 years ago along with females bearing the maternal haplogroup L3, which the study also hypothesizes to have originated in Eurasia, into Africa ¹. This back migration is also supported by the presence of some Eurasian mtDNA haplogroups, such as M and N, in some African populations, such as the Berbers and the Ethiopians. The back-migrated E carriers are thought to have mixed with the local African populations, and to have contributed to the genetic and cultural diversity of the continent. E is associated with various historical and prehistoric events and movements in Africa, such as the Bantu expansion, the Afro-Asiatic languages, the Nile Valley civilizations, and the Islamic conquests. E is also found in some populations outside of Africa, such as the Arabs, the Jews, the Romans, and the Vikings, due to ancient and medieval migrations and trade.

D, on the other hand, is the most restricted and isolated branch of DE, and is found mainly in some regions of Asia, such as the Andaman Islands, Tibet, Japan, and Mongolia. D is composed of several subclades, such as D-M15, D-M55, D-M64, and D-M174, which have different geographic and demographic histories. D is also the most ancient haplogroup among living humans, and shows evidence of archaic admixture from other hominin species, such as the Denisovans. The origin and dispersal of D is also a matter of debate among geneticists and anthropologists. Some researchers have argued that D originated in Africa and migrated to Asia, while others have proposed that D originated in Asia and diversified there. The latter hypothesis is based on the observation that D shares a common ancestor with E, which is mainly found in Africa, and that D shows a higher diversity and frequency in East Asia than in South Asia, suggesting a recent expansion from the east.

According to this hypothesis, after the divergence of E and D around 55,000 years ago, D-carrying males are proposed to have migrated and expanded across Asia, following different routes and adapting to different environments. D is associated with various historical and prehistoric events and movements in Asia, such as the peopling of the Andaman Islands, the Tibetan Plateau, the Japanese archipelago, and the Mongolian steppes. D is also found in some populations outside of Asia, such as the Melanesians, the Polynesians, and the Native Americans, due to ancient and recent migrations and admixture.

THE DESCENDANTS AND AFFILATIONS OF DE

DE and its descendants, E and D, represent a significant and diverse part of the human genetic heritage, and reflect the complex and dynamic history of human migrations and interactions. DE and its subclades are found in various populations and cultures around the world, and show different degrees of affinity and relatedness. The descendants of DE can be identified by genetic testing, which can reveal the haplogroup and subclade of an individual or a group. Genetic testing can also provide information about the geographic origin, the ancestral ethnicity, the genealogical connections, and the health risks of the tested person or population. Genetic testing can also be used to compare and contrast the genetic profiles of different groups and individuals, and to infer their evolutionary and historical relationships. One way to measure the genetic affinity and relatedness of different groups and individuals is to use a phylogenetic tree, which is a diagram that shows the evolutionary history and the degree of similarity of different haplogroups and subclades. A phylogenetic tree can be constructed based on the genetic markers or mutations that define each haplogroup and subclade, and can be used to estimate the time of divergence and the common ancestry of different branches.

Another way to measure the genetic affinity and relatedness of different groups and individuals is to use a principal component analysis (PCA), which is a statistical method that reduces the dimensionality of a large set of variables and identifies the main patterns of variation. A PCA can be applied to a large set of genetic data, such as single nucleotide polymorphisms (SNPs), and can be used to plot the genetic coordinates of different groups and individuals on a two-dimensional graph, where the distance and the direction reflect the degree and the nature of the genetic similarity and difference. Using these methods, we can see that DE and its descendants, E and D, show different patterns of genetic affinity and relatedness with other haplogroups and populations. For example, a phylogenetic tree based on Y-STR data shows that DE is closely related to CT and its subclades, such as CF and K, which are mainly found in Eurasia and Oceania, and that E and D are more distant from each other than from their common ancestor, DE ². A PCA based on autosomal SNP data shows that E is more genetically similar to other African haplogroups, such as A and B, and to some Eurasian haplogroups, such as J and R, while D is more genetically similar to other Asian haplogroups, such as O and C, and to some Oceanian haplogroups, such as K and M.

CONCLUSION

Y haplogroup DE is a paternal genetic lineage that originated in Asia around 65,000 years ago, and split into two main branches: E and D, which have distinct geographic and demographic histories. E is the most common haplogroup among African populations, and is thought to have back-migrated from Eurasia to Africa around 70,000 years ago, along with some maternal lineages. D is the most common haplogroup among some Asian populations, such as the Andamanese, Tibetans, and Japanese, and is the most ancient haplogroup among living humans, showing evidence of archaic admixture. DE and its descendants, E and D, represent a significant and diverse part of the human genetic heritage, and reflect the complex and dynamic history of human migrations and interactions. DE and its subclades can be identified by genetic testing, and can be compared and contrasted with other haplogroups and populations, using methods such as phylogenetic trees and principal component analysis. By studying the ancient origins and dispersal of DE and its descendants, we can gain a better understanding of the evolutionary and historical relationships among different groups and individuals, and of the genetic and cultural diversity of humanity.

REFERENCES

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