Out of Africa again and again...and again

[Daryl Habel]

Although first published online in the Yearbook of Physical Anthropology on Dec 20, 2005, a new paper by Alan Templeton has reached the major news media outlets this week: CLICK HERE FOR NEWS RELEASE.

The abstract of the new paper

American Journal of Physical Anthropology
Volume 128, Issue S41 , Pages 33 - 59

Haplotype Trees and Modern Human Origins (p 33-59)

Alan R. Templeton

Abstract

A haplotype is a multisite haploid genotype at two or more polymorphic sites on the same chromosome in a defined DNA region. An evolutionary tree of the haplotypes can be estimated if the DNA region had little to no recombination. Haplotype trees can be used to reconstruct past human gene-flow patterns and historical events, but any single tree captures only a small portion of evolutionary history, and is subject to error. A fuller view of human evolution requires multiple DNA regions, and errors can be minimized by cross-validating inferences across loci. An analysis of 25 DNA regions reveals an out-of-Africa expansion event at 1.9 million years ago. Gene flow with isolation by distance was established between African and Eurasian populations by about 1.5 million years ago, with no detectable interruptions since. A second out-of-Africa expansion occurred about 700,000 years ago, and involved interbreeding with at least some Eurasian populations. A third out-of-Africa event occurred around 100,000 years ago, and was also characterized by interbreeding, with the hypothesis of a total Eurasian replacement strongly rejected (P < 10-17). This does not preclude the possibility that some Eurasian populations could have been replaced, and the status of Neanderthals is indecisive. Demographic inferences from haplotype trees have been inconsistent, so few definitive conclusions can be made at this time. Haplotype trees from human parasites offer additional insights into human evolution and raise the possibility of an Asian isolate of humanity, but once again not in a definitive fashion. Haplotype trees can also indicate which genes were subject to positive selection in the lineage leading to modern humans. Genetics provides many insights into human evolution, but those insights need to be integrated with fossil and archaeological data to yield a fuller picture of the origin of modern humans.

AVAILABLE HERE for those with wiley.com access.

This paper furthers the previous work by Templeton, "Out of Africa again and again", which was published in the journal Nature vol. 416: 45-51 (2002): CLICK HERE, in which Templeton used what he calls "nested clade analyses" of phylogeographic data and 10 haplotype trees to reject the idea of a total replacement of archaic populations by recent OoA migrants.  In this new paper, Templeton has expanded the analysis to include 25 DNA "regions", and he claims this solidly confirms the earlier work.  I haven't read this new paper yet, but it should be interesting to see what staunch replacementists use as arguments to refute Templeton's assertion.

Dar

[lagarvelho]

Dar:

I wonder if anybody can get hold of the full paper and pass it on to me for download.  Or are there "copyright" problems?  I've read a number of Templeton papers on more or less the same theme over the years.
Anne G

[Daryl Habel]

Dar:

I wonder if anybody can get hold of the full paper and pass it on to me for download.  Or are there "copyright" problems?  I've read a number of Templeton papers on more or less the same theme over the years.
Anne G

I suggest you make that request on your group site.  I have now read the new paper, but the way it was sent to me was in three files totalling nearly nearly 12 MB (your entire capacity is only 20 MB), and, unfortunately, was missing the last three pages (the references), so it isn't complete anyway.  I can say that this new paper is a very detailed look at the many ways haplotype trees have been used in past interpretations of human evolutionary history, and Templeton has gone to great lengths explaining the limitations of  single-locus haplotype tree interpretations.  He then goes on to explain the greater advantages of nested clade analyses of multiple loci (his method).  After a first reading, I can say he does a very good job of explaining all this in terms I can understand, but I have to admit I cannot really verify whether the methodology is all he claims it to be.  I'll be looking forward to what John Hawks has (promised HERE) to say on his weblog, after he's had a chance to look through the paper.

Or what anyone else who has an opinion might have to offer here.

Dar

[lagarvelho]

Dar:

12 MB!  Yikes!  However, since I have downloaded(to my files)and printed the whole thing, I probably won't clutter up Palanthsci's files with this mosnter.  Unless, of course, somebody requests it specifically.  OTOH, I fully intend to read it.  While it was printing, I noticed it was full of graphs, but as of now, I can't say anything more about it.  When I have read it, I will probably share my thoughts, for what they're worth.
Anne G