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For perhaps the first 100,000 years or more, genetic variation was developing as human populations largely migrated within Africa between 300,000-200,000 years ago. Anatomically modern humans derived from these <i>Homo sapiens</i> species, although by then other similar sub-species, such as Neanderthals, had existed. Genetically, Y-chromosomal Adam, or the genetic ancestor for all living men today (i.e., although this does not mean he was genetic Adam was the only man around), seems to derive between 300,000-200,000 years ago, suggesting that the ancestor to all males derived during the very early evolution of modern humans rather than within a much later sub-population. Central to Western Africa seem to be the regions where this early human ancestor influenced subsequent populations. For genetic Eve, or the most recent common matrilineal ancestor Mitochondrial DNA for all humans, is harder to specify, where the dates can range between more than 120,000 years agoor perhaps more similar in time to genetic Adam. There were likely many female genetic lines but Mitochondrial Eve likely became the only female linethat survived. All of these early dates suggest greater human diversity and variation were originating and developing in Africafor the first 100,000 years or more of modern humans, long before migrations began to significantly shape subsequent human populations in other parts of the Earth. <ref>For more on genetic Adam and Eve, see: Callaway, E. (2013) Genetic Adam and Eve did not live too far apart in time. <i>Nature.</i> [Online] Available from: doi:10.1038/nature.2013.13478 [Accessed: 12 June 2017].</ref>

As stated, for most human populations, the vast majority of it can be traced to a large wave of migrations that occurred between 80-50 thousand years ago. Overall, humans are about 99.5% similar to each other, suggesting that relatively few populations have influenced the vast majority of our genetic makeup. In Africa, using linguistic and genetic evidence, there were likely about 14 main population groups. These groups show a wider range of genetic variability than many other populations throughout the Earth, which suggests that humans spent a lot of time in Africa before they successfully spread due to founder effects and colonized the remaining parts isolation of Earth very early humans that evolved over 200,000 years ago (Figure 2). Modern African populations in eastern Africa, between Namibia and South Africa, are likely the most similar to other human populationsfound in other parts of the world, which suggests that it was this region that modern humans began the large, second wave migration(s) that eventually colonized the rest of the planet.<ref>For more on the great migration that have subsequently influenced human populations, see: Yotova, V., Lefebvre, J.-F., Moreau, C., Gbeha, E., et al. (2011) An X-Linked Haplotype of Neandertal Origin Is Present Among All Non-African Populations. <i>Molecular Biology and Evolution</i>. [Online] 28 (7), 1957–1962. Available from: doi:10.1093/molbev/msr024.</ref>

Divergence in genetics began to accelerate again at about 40,000 years ago, by which time European and Asian populations began to diverge as human populations migrated into different parts of Eurasia, where the Middle East and Central Asia became an area where human populations diverged from. In southeast Asia, the Denisova hominin, an early hominid that shares an ancestor with Neanderthals, may have also bred with early modern humans, similar to Neanderthals in Europe and other parts of Asia. This could explain why up to 4-6% of southeast Asian populations' genetic makeup shows variation from other populations. Additionally, sub-Sahara African populations not only show large variation, but their genetic makeup lacks any genetic input from Neanderthals, suggesting Neanderthals never migrated to areas south of the Sahara.On the other hand, Central Asian, European, and Middle Eastern populations do show input from Neanderthals, altough not at very high rates<ref>For more on post-Africa migration genetic divergence, see: Barbujani, G. & Bertorelle, G. (2001) Genetics and the population history of Europe. <i>Proceedings of the National Academy of Sciences.</i> [Online] 98 (1), 22–25. Available from: doi:10.1073/pnas.98.1.22.</ref>