What is the Out-of-Africa theory?
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Answers
Explanation:
In paleoanthropology, the recent African origin of modern humans, also called the "Out of Africa" theory, recent single-origin hypothesis, replacement hypothesis, or recent African origin model, is the dominant model of the geographic origin and early migration of anatomically modern humans.
Answer:
Broadly speaking, there are two competing hypotheses on the origin of modern humans: the Out-of-Africa hypothesis and the multiregional hypothesis. Both agree that Homo erectus originated in Africa and expanded to Eurasia about one million years ago, but they differ in explaining the origin of modern humans (Homo sapiens sapiens). The first hypothesis proposes that a second migration out of Africa happened about 100,000 years ago, in which anatomically modern humans of African origin conquered the world by completely replacing archaic human populations (Homo sapiens; Model A). The multiregional hypothesis states that independent multiple origins (Model D) or shared multiregional evolution with continuous gene flow between continental populations (Model C) occurred in the million years since Homo erectus came out of Africa (the trellis theory). A compromised version of the Out-of-Africa hypothesis emphasizes the African origin of most human populations but allows for the possibility of minor local contribution.
The supposed interrelation of cultural achievement and the shape and size of teeth, jaws, and brain is a theorized state of affairs with which some paleoanthropologists disagree. Throughout the human fossil record there are examples of dissociation between skull shape and size on the one hand and cultural achievement on the other. For example, a smaller-brained H. erectus may have been among the first humans to tame fire, but much bigger-brained people in other regions of the world living later in time have left no evidence that they knew how to handle it. Gradualism is at the core of the so-called “multiregional” hypothesis (see human evolution), in which it is theorized that H. erectus evolved into Homo sapiens not once but several times as each subspecies of H. erectus, living in its own territory, passed some postulated critical threshold. This theory depends on accepting a supposed erectus-sapiens threshold as correct. It is opposed by supporters of the “out of Africa” hypothesis, who find the threshold concept at variance with the modern genetic theory of evolutionary change.