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→Lack of Genetic Diversity
In east Asia, east Siberia, Korea, and Japan may have been reached by 35,000 years ago by modern humans. This population that migrated to this region also led to a sub-population that became the first colonizers of the Americas. It is not clear when, but between 40,000-16,500 years ago, modern human migrated over the Beringia land bridge, likely using the ice sheets that formed in the late glacial maximum period when ice sheets and glaciers covered many parts of North America. Recent genetic work has shown that human populations in the Amazon are genetically similar to Australoid populations, or populations that also migrated to east Asia and Australia. In effect, human migrations to the Americas likely traveled along the coastal regions between North and South America.
==Lack of Genetic Diversity== 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 and colonized the remaining parts of Earth. Modern African populations in eastern Africa, between Namibia and South Africa, are likely the most similar to other human populations, 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. 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. In southeast Asia, 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.
==Summary==
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