Origin of modern humans
Recent African origin
The recent African origin of modern humans is the mainstream model describing the origin and early dispersal of anatomically modern humans. The theory is called the (Recent) Out-of-Africa model in the popular press, and academically the recent single-origin hypothesis (RSOH), Replacement Hypothesis, and Recent African Origin (RAO) model. The hypothesis that humans have a single origin (monogenesis) was published in Charles Darwin's Descent of Man (1871). The concept was speculative until the 1980s, when it was corroborated by a study of present-day mitochondrial DNA, combined with evidence based on physical anthropology of archaic specimens. According to genetic and fossil evidence, archaic Homo sapiens evolved to anatomically modern humans solely in Africa, between 200,000 and 100,000 years ago, with members of one branch leaving Africa by 60,000 years ago and over time replacing earlier human populations such as Neanderthals and Homo erectus.
The recent single origin of modern humans in East Africa is the near-consensus position held within the scientific community. However, recent sequencing of the full Neanderthal Genome suggests Neanderthals and some modern humans share some ancient genetic lineages. The authors of the study suggest that their findings are consistent with Neanderthal admixture of up to 4% in some populations. But the study also suggests that there may be other reasons why humans and Neanderthals share ancient genetic lineages. In August 2012, a study by scientists at the University of Cambridge has questioned this conclusion, hypothesising instead that the DNA overlap is a remnant of a common ancestor of both Neanderthals and modern humans.
The multiregional origin of modern humans is a scientific model that provides an explanation for the pattern of human evolution proposed by Milford H. Wolpoff in 1988. Multiregional origin holds that the evolution of humanity from the beginning of the Pleistocene 2.5 million years BP to the present day has been within a single, continuous human species, evolving worldwide to modern Homo sapiens.
- Hua Liu, et al. A Geographically Explicit Genetic Model of Worldwide Human-Settlement History. The American Journal of Human Genetics, volume 79 (2006), pages 230–237, quote: Currently available genetic and archaeological evidence is generally interpreted as supportive of a recent single origin of modern humans in East Africa. However, this is where the near consensus on human settlement history ends, and considerable uncertainty clouds any more detailed aspect of human colonization history.
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