World Dispersals and Genetic Diversity of Mankind: The Out-of-Africa Theory and Its Challenges

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The publication of an analysis of human mitochondrial DNA in 1987 vaulted a classic model of human evolution, the out-of-Africa replacement (OAR), to become the dominant model of human evolution for a quarter of a century. This model posits that long after humans spread out of Africa into Eurasia at the Homo erectus stage, anatomically modern humans first evolved in Africa, expanded out of Africa into Eurasia sometime between 60,000 and 130,000. years ago, and completely replaced all the archaic human populations they encountered, driving them all to total genetic extinction. The genetic data were interpreted and presented as having falsified the multiregional model of human evolution in which modern humans had no single geographical origin because of gene flow (genetic interchange) among archaic populations. However, this falsification was based on a mistaken portrayal of the multiregional model as having little to no gene flow. Other models of human evolution were mostly ignored. Although much genetic data seemed to support the OAR model, in actuality, no genetic data set ever significantly favored the OAR model when placed into a hypothesis testing framework, and several genetic data sets and analyses strongly rejected or falsified replacement. Nevertheless, replacement remained dominant until the sequencing of ancient DNA provided direct confirmation that limited interbreeding, not complete replacement, had occurred, as had been inferred through hypothesis testing many years earlier. Ignoring the results of rigorous hypothesis testing still plagues the area of human evolution, particularly in the common portrayal of human "races" as separate branches of an evolutionary tree of human populations even though the hypothesis of a tree of human populations has been strongly rejected by all tested data.

Original languageEnglish
Title of host publicationOn Human Nature
Subtitle of host publicationBiology, Psychology, Ethics, Politics, and Religion
Number of pages19
ISBN (Electronic)9780127999159
ISBN (Print)9780124201903
StatePublished - 2017

Bibliographical note

Publisher Copyright:
© 2017 Elsevier Inc. All rights reserved.


  • Admixture
  • Gene flow
  • Human evolution
  • Population trees
  • Race

ASJC Scopus subject areas

  • General Agricultural and Biological Sciences
  • General Biochemistry, Genetics and Molecular Biology


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