Multiregional origin of modern humans

The multiregional hypothesis, multiregional evolution (MRE), or polycentric hypothesis, is a scientific model that provides an alternative explanation to the more widely accepted "out of Africa" model of monogenesis for the pattern of human evolution.

Multiregional evolution holds that the human species first arose around two million years ago and subsequent human evolution has been within a single, continuous human species. This species encompasses all archaic human forms such as Homo erectus and Neanderthals as well as modern forms, and evolved worldwide to the diverse populations of anatomically modern humans (Homo sapiens).

The hypothesis contends that the mechanism of clinal variation through a model of "centre and edge" allowed for the necessary balance between genetic drift, gene flow, and selection throughout the Pleistocene, as well as overall evolution as a global species, but while retaining regional differences in certain morphological features.^[1] Proponents of multiregionalism point to fossil and genomic data and continuity of archaeological cultures as support for their hypothesis.

The multiregional hypothesis was first proposed in 1984, and then revised in 2003. In its revised form, it is similar to the assimilation model, which holds that modern humans originated in Africa and today share a predominant recent African origin, but have also absorbed small, geographically variable, degrees of admixture from other regional (archaic) hominin species.^[2]

The multiregional hypothesis is not currently the most accepted theory of modern human origin among scientists. "The African replacement model has gained the widest acceptance owing mainly to genetic data (particularly mitochondrial DNA) from existing populations. This model is consistent with the realization that modern humans cannot be classified into subspecies or races, and it recognizes that all populations of present-day humans share the same potential."^[3] The African replacement model is also known as the "out of Africa" theory, which is currently the most widely accepted model. It proposes that Homo sapiens evolved in Africa before migrating across the world."^[4] And: "The primary competing scientific hypothesis is currently recent African origin of modern humans, which proposes that modern humans arose as a new species in Africa around 100-200,000 years ago, moving out of Africa around 50-60,000 years ago to replace existing human species such as Homo erectus and the Neanderthals without interbreeding.^[5][6][7][8] This differs from the multiregional hypothesis in that the multiregional model predicts interbreeding with preexisting local human populations in any such migration."^[8][9]