Skepticism About "Out-of-Africa"

 
Alan R. Templeton has long been a critic of those who would over-interpret the genetic data on human origins. He's not alone. There are a surprisingly large number of biologists who refuse to jump on the "Out-of-Africa" bandwagon. This group does not get the same amount of publicity as the advocates of a recent (<100,000 years) wave of migration out of Africa. I think it's because skepticism of a new theory is seen as sour grapes. That, plus the fact that it's hard to publish criticisms of work that's already in the scientific literature.

An upcoming issue of the journal Evolution will contain a review by Templeton on human origins and the Out-of-Africa theory. Right now it's only available online [GENETICS AND RECENT HUMAN EVOLUTION]. Here's the abstract,

Starting with "mitochondrial Eve" in 1987, genetics has played an increasingly important role in studies of the last two million years of human evolution. It initially appeared that genetic data resolved the basic models of recent human evolution in favor of the "out-of-Africa replacement" hypothesis in which anatomically modern humans evolved in Africa about 150,000 years ago, started to spread throughout the world about 100,000 years ago, and subsequently drove to complete genetic extinction (replacement) all other human populations in Eurasia. Unfortunately, many of the genetic studies on recent human evolution have suffered from scientific flaws, including misrepresenting the models of recent human evolution, focusing upon hypothesis compatibility rather than hypothesis testing, committing the ecological fallacy, and failing to consider a broader array of alternative hypotheses. Once these flaws are corrected, there is actually little genetic support for the out-of-Africa replacement hypothesis. Indeed, when genetic data are used in a hypothesis-testing framework, the out-of-Africa replacement hypothesis is strongly rejected. The model of recent human evolution that emerges from a statistical hypothesis-testing framework does not correspond to any of the traditional models of human evolution, but it is compatible with fossil and archaeological data. These studies also reveal that any one gene or DNA region captures only a small part of human evolutionary history, so multilocus studies are essential. As more and more loci became available, genetics will undoubtedly offer additional insights and resolutions of human evolution.

[Hat Tip: Gene Expression]