Prehistoric human migrations are the earliest migrations and expansions of archaic and modern humans across continents beginning 2 million years ago with the out of Africa migration of Homo erectus. This initial migration was followed by other archaic humans including H. heidelbergensis, which lived around 500,000 years ago and was the likely ancestor of both Denisovans and Neanderthals. Early hominids were said to have "crossed land bridges that were eventually covered in water" (History Alive, pub. 2004, TCI).
Within Africa, Homo sapiens dispersed around the time of its speciation, roughly 300,000 years ago. The "recent African origin" paradigm suggests that the anatomically modern humans outside of Africa descend from a population of Homo sapiens migrating from East Africa roughly 70,000 years ago and spreading along the southern coast of Asia and to Oceania before 50,000 years ago. Modern humans spread across Europe about 40,000 years ago.
The migrating modern human populations are known to have interbred with local varieties of archaic humans, so that contemporary human populations are descended in small part (below 10% contribution) from regional varieties of archaic humans.
After the Last Glacial Maximum, North Eurasian populations migrated to the Americas about 20,000 years ago. Northern Eurasia was peopled after 12,000 years ago, in the beginning Holocene. Arctic Canada and Greenland were reached by the Paleo-Eskimo expansion around 4,000 years ago. Finally, Polynesia was peopled after 2,000 years ago, by the Austronesian expansion.
When humans first ventured out of Africa some 60,000 years ago, they left genetic footprints still visible today. By mapping the appearance and frequency of genetic markers in modern peoples, we create a picture of when and where ancient humans moved around the world. These great migrations eventually led the descendants of a small group of Africans to occupy even the farthest reaches of the Earth.
Our species is an African one: Africa is where we first evolved, and where we have spent the majority of our time on Earth. The earliest fossils of recognizably modern Homo sapiens appear in the fossil record at Omo Kibish in Ethiopia, around 200,000 years ago. Although earlier fossils may be found over the coming years, this is our best understanding of when and approximately where we originated.
According to the genetic and paleontological record, we only started to leave Africa between 60,000 and 70,000 years ago. What set this in motion is uncertain, but we think it has something to do with major climatic shifts that were happening around that time—a sudden cooling in the Earth’s climate driven by the onset of one of the worst parts of the last Ice Age. This cold snap would have made life difficult for our African ancestors, and the genetic evidence points to a sharp reduction in population size around this time. In fact, the human population likely dropped to fewer than 10,000. We were holding on by a thread.
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South America Animated Map of Prehistoric Human Migration | |
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| Education Blood Moon-14763 Dhruva Aliman | Upload TimePublished on 9 Mar 2019 |
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