Hominin interbreeding and the evolution of human variation.

Kwang Hyun Ko

doi:10.1186/s40709-016-0054-7

Abstract

Mitochondrial Eve confirms the “out of Africa” theory, but the evidence also supports interbreeding between Homo sapiens and other hominins: Neanderthals, Denisovans, and Homo heidelbergensis. This article explains how interbreeding between early H. sapiens and archaic hominins occurred. The availability of edible insects in East Asia aided the spread of the unaggressive, highly cooperative Neanderthals, who interbred with H. sapiens in Asia, resulting in a higher admixture of Neanderthal DNA in East Asian populations. Geographical variation in degree of interbreeding between H. sapiens and Neanderthals likely contributed to neurological and behavioral differences in modern humans. Similarly, people with Denisovan genetic admixture were better able to dwell in mountainous regions, allowing their genetic legacy to cross the Himalayas and persist in Southeast Asian and Oceanian H. sapiens. In the Sub-Saharan region, unaffected by Denisovan or Neanderthal interbreeding, H. sapiens interbred with H. heidelbergensis, because high humidity militated against fire-making and allowed the survival of these non-fire-making hominins.

Highlights

There are two branching hypotheses on the origin of the human species
DNA analysis demonstrating the existence of “Mitochondrial Eve” has strongly corroborated the recent African origin model of out of Africa” (OOA) by providing crucial support to the theory that H. sapiens moved from Africa to replace residing hominin populations elsewhere [4]
Most hominins other than Denisovans and Neanderthals were replaced by H. sapiens that migrated out of Africa, but sufficient interbreeding occurred with Denisovans and Neanderthals in Eurasia to leave a significant mark on modern human DNA [15]

Summary

Introduction

There are two branching hypotheses on the origin of the human species. The most widely accepted is the “out of Africa” (OOA) theory, which holds that archaic Homo sapiens evolved into anatomically modern humans solely in Africa between 200,000 and 60,000 years ago [1]. Most hominins other than Denisovans and Neanderthals were replaced by H. sapiens that migrated out of Africa, but sufficient interbreeding occurred with Denisovans and Neanderthals in Eurasia to leave a significant mark on modern human DNA [15]. The evidence has shown that in addition to interbreeding, Neanderthals were very often killed by H. sapiens, and in related findings, genetic studies have shown that the mutations in ADSL, GLDC, and SLITRK1 genes, which are associated with hyperactivity and aggressive behavior in modern humans, were not found in Neanderthals [19,20,21].

Results

Conclusion