Unraveling the Mystery of Human Evolution

"Out of Africa" Theory of the Early Migration of Humans:

• The recent African origin of modern humans is the dominant model of the geographic origin and early migration of anatomically modern humans.

• Homo sapiens most likely developed in the Horn of Africa between 300,000 and 200,000 years ago.

• There were at least several "out-of-Africa" dispersals of modern humans, possibly beginning as early as 270,000 years ago.

• Practically all of these early waves seem to have gone extinct or retreated back, and present-day humans outside Africa descend mainly from a single expansion out 70,000–50,000 years ago.

• The most significant "recent" wave out of Africa took place about 70,000–50,000 years ago, via the so-called "Southern Route", spreading rapidly along the coast of Asia and reaching Australia by around 65,000–50,000 years ago.

• Studies in population genetics uncovered evidence of interbreeding that occurred between H. sapiens and archaic humans in Eurasia, Oceania, and Africa.

• The "recent African origin" model proposes that all modern non-African populations are substantially descended from populations of H. sapiens that left Africa after that time.

• The "recent out-of-Africa" migration took place in a number of waves spread over a long time period.

• The two main accepted dispersal routes for the out-of-Africa migration of early anatomically modern humans are the "Northern Route" (via Nile Valley and Sinai) and the "Southern Route" via the Bab-el-Mandeb strait.

• By some 50–70,000 years ago, a subset of the bearers of mitochondrial haplogroup L3 migrated from East Africa into the Near East.

• According to one study, Papuans could have either formed from a mixture between an East Eurasian lineage and lineage basal to West and East Asians, or as a sister lineage of East Asians.

• An indigenous American sample from 16,000BC in Idaho, which is craniometrically similar to modern Native Americans as well as Paleosiberias, was found to have largely East-Eurasian ancestry and showed high affinity with contemporary East Asians, as well as Jōmon period samples of Japan.Recent African Origin Theory of Modern Humans

• Posth et al. (2016) argue for a "rapid single dispersal of all non-Africans less than 55,000 years ago."

• Mitochondrial haplogroups L0, L1, L2, and L3 are largely confined to Africa, while haplogroups M and N are found outside Africa and are about 65-55,000 years old.

• The female descendants of only one lineage, mtDNA haplogroup L3, are found outside Africa, which supports the idea of a single dispersal event from Africa.

• The southern coastal dispersal would have occurred before the dispersal through the Levant approximately 45,000 years ago, and haplogroup N is predominant in Europe, while haplogroup M is predominant in East Asia.

• Autosomal DNA analysis found greater genetic diversity among Africans than among Eurasians, supporting the out of Africa model.

• Natural selection in autosomal DNA outside of Africa was found, with Papua New Guineans continuing to be exposed to selection for dark skin color, indicating convergent evolution.

• The JC virus has been used as a genetic marker for human evolution and migration, but does not appear to be reliable for the migration out of Africa.

• Evidence for archaic human species having interbred with modern humans outside of Africa was discovered in the 2010s, with Neanderthal admixture in all modern populations except for Sub-Saharan Africans and Denisova hominin admixture in Australasia.

• Admixture from archaic hominins of still earlier divergence times was found in Pygmies, Hadza, and five Sandawe in 2012.

• Mucin 7, a highly divergent haplotype specific to African populations, is inferred to have been derived from interbreeding between African modern and archaic humans.

• The Yoruba and Mende populations of West Africa derive between 2% and 19% of their genome from an as-yet unidentified archaic hominin population that likely diverged before the split of modern humans and the ancestors of Neanderthals and Denisovans.

• Small stone tools (microlithic materials) from the Indian subcontinent could be dated to 35 ka in South Asia, and the new technology might be influenced by environmental change and population pressure.Extinction of Neanderthal patrilineages suggested by a 2016 study

• The study suggests that the Neanderthal patrilineage is not present in modern humans and may have gone extinct.

• This is based on the analysis of the Neanderthal Y chromosome, which is different from that of modern humans.

• The study also suggests that the Neanderthal patrilineage may have originated from a population of Homo erectus that lived in Asia.

• The study raises questions about the evolutionary history of the Neanderthals and their relationship to other hominid species.

• The study used ancient DNA sequencing to analyze the Y chromosome of two Neanderthal individuals.

• The study found that the Neanderthal Y chromosome is more closely related to that of Denisovans than to modern humans.

• The study suggests that the Neanderthal patrilineage may have been lost due to genetic drift or other factors.

• The study highlights the importance of ancient DNA sequencing in understanding human evolution and history.

• The study has implications for the debate on the relationship between Neanderthals and modern humans.

• The study suggests that the extinction of the Neanderthal patrilineage may have contributed to the genetic diversity of modern humans.

• The study provides new insights into the evolutionary history of the Neanderthals and their relationship to other hominid species.

• The study raises new questions about the origins and evolution of human populations.