June 22, 2004
Estimating the Impact of Prehistoric Admixture on the Genome of Europeans
A study similar to past work by Chikhi who had found a large percentage of Neolithic ancestry in Europeans. This study uses four parental groups instead of Chikhi's Paleolithic/Neolithic. A remaining weakness is that Basques are not representative of Paleolithic Europeans, since Haplogroup I which had a Balkan/South Euro focus in UP times represents non-Basque UP European ancestry.
MBE Advance Access originally published online on March 24, 2004
Mol. Biol. Evol. 21(7):1361-1372. 2004
Isabelle Dupanloup et al.
Abstract
We inferred past admixture processes in the European population from genetic diversity at eight loci, including autosomal, mitochondrial and Y-linked polymorphisms. Admixture coefficients were estimated from multilocus data, assuming that most current populations can be regarded as the result of a hybridization process among four or less potential parental populations. Two main components are apparent in the Europeans' genome, presumably corresponding to the contributions of the first, Paleolithic Europeans, and of the early, Neolithic farmers dispersing from the Near East. In addition, only a small fraction of the European alleles seems to come from North Africa, and a fourth component reflecting gene flow from Northern Asia is largely restricted to the northeast of the continent. The estimated Near Eastern contribution decreases as one moves from east to west, in agreement with the predictions of a model in which (Neolithic) immigrants from the Near East contributed a large share of the alleles in the genome of current Europeans. Several tests suggest that probable departures from the admixture models, due to factors such as choice of the putative parental populations and more complex demographic scenarios, may have affected our main estimates only to a limited extent.
Posted by Dienekes at June 22, 2004 06:24 PM | PermaLinkI think it has been pretty much established that the only Middle-Eastern/North African Y-chromosomes to enter Europe during the Neolithic were Haplogroups E and J. Lounès Chikhi reminds me of Milford Wolpoff in that he persists in promoting a scientific argument that most geneticists reject.
Posted by: Xguy at June 23, 2004 05:42 AMxguy: While I am not familiar with Chikhi's ideas, most geneticists will agree that single locus studies aren't reliable enough. We'll need to see more autosomal work done.
Posted by: David Perkins at June 23, 2004 05:53 PMChikhi and these people try to quantify the parental population contributions within a statistical framework as opposed to a naive "haplogroup-counting" approach. Defining the parental populations is tricky, but this is more promising than the other approach.
Posted by: Dienekes at June 23, 2004 06:17 PMChikhi and these people try to quantify the parental population contributions within a statistical framework as opposed to a naive "haplogroup-counting" approach.
Haplogroups R and I which comprise most western, northern and eastern European Y-chromosomes are rare in the Middle East and so are unlikely to have originated there in the Neolithic. Haplogroup I does have Middle Eastern ancestry but that was back in the Paleolithic, not the Neolithic. Haplogroup R is almost certainly of Central Asian ancestry. As for Chikhi's "statistical framework" it reminds me of that old saying about lies, damned lies and statistics.
Posted by: Xguy at June 24, 2004 05:49 AM>> Haplogroups R and I which comprise most western, northern and eastern European Y-chromosomes are rare in the Middle East and so are unlikely to have originated there in the Neolithic.
R came to Europe from the East, hence it would be present in Neolithic farmers.
Posted by: Dienekes at June 24, 2004 02:59 PMR came to Europe from the East, hence it would be present in Neolithic farmers.
Haplogroup R came from Central Asia, not the Middle East. Secondly, it came over 20,000 years ago, not during the Neolithic.
Posted by: Xguy at June 28, 2004 06:18 AM>> Haplogroup R came from Central Asia, not the Middle East. Secondly, it came over 20,000 years ago, not during the Neolithic.
Yes, but the movements of "R" people were not limited towards Europe. Some of them went to India, others to the East, others to Europe and others to the Near East, or even into Africa where there is a presence of "R" chromosomes in Cameroon.
So, "R" chromosomes were likely present in both the Near East and Europe at the onset of the Neolithic and thus some "R" chromosomes were likely included in the Neolithic dispersals into Europe.
Posted by: Dienekes at June 28, 2004 03:19 PMHaplogroups J and E are much more common in the Middle East than R is so if R in Europe comes from Middle Eastern Neolithic farmers then how come the levels of J and E are not higher in Europe? Except for Chikhi, most researchers seem to accept that Haplogroup R (M173) came to Europe from Central Asia not the Middle East.
Posted by: Xguy at June 30, 2004 06:47 AMR doesn't necessarily come from a single source, nor did it necessarily arrive in a single wave. If Iraqis moved to Ireland today, they'd bring some R Y chromosomes with them.
Posted by: Dienekes at July 1, 2004 11:41 PM