Genes, Fossils, and Culture. An Overview of the Evidence for Neandertal–Modern Human Interaction and Admixture

Abstract

This paper re-examines current arguments concerning the evidence for Neandertal-modern human interaction and admixture. While most researchers now agree that the ancestry of all present day humans can be traced back to African late Middle Pleistocene populations, at a time when the remainder of Eurasia was inhabited by ‘archaic humans’, most notably the Neandertals, issues that remain to be resolved are the tempo and mode of early modern human dispersal and interaction with archaic humans.This paper focuses on what happened at the time of contact in Europe, and assesses the level of admixture that may have occurred, as well as the extent to which such level may have varied in both time and space. It explains how the available mtDNA evidence does not preclude admixture at the time of contact, and is in fact consistent, depending on a number of parameters, with a possibly substantial Neandertal contribution to the initial modern human population of Europe. It is argued that the absence of Neandertal mtDNA lineages among present Europeans is likely, on dating evidence, to be simply a particular case of generalised loss of Pleistocene mtDNA lineages. Although the full range of interaction types (mutual avoidance, hostile confrontation, full integration) is conceivable, there is plenty of archaeological evidence to suggest that admixture must have been the general rule, and that the paleontological evidence for the generalised presence of archaic traits among Europe's earliest moderns implies the transmission of genes, and indicates that mixed groups should have been reproductively viable. In this context, it would seem that the most parsimonious explanation for the disappearance of the Neandertal mtDNA lineage is genetic swamping.