keskiviikko 25. maaliskuuta 2015

Near Eastern admixture in South Europe

Haak et al. 2015 has led to confusion about the genetic shape of Southern Europeans.  Two examples  about those challenging points:

Sardinians 89.8% EN+3.2% WHG+7.1% Yamnaya
Ashkenazi 90.7% EN+0% WHG+9.3% Yamnaya

and later

Ashkenazi_Jew 3.7% EHG+95.5% EN+0.8% Nganassan+0% WHG 

EN stands for Early Neolithic Europeans, samples are very likely from Neolithic Hungary. 

Results show only a small difference in resnorm values between results.  Are Ashkenazim more original Southern Europeans than European themselves?  How we could explain this shift between original Europeans and original Near Easterners?   IMO,  it is quite hard to believe this kind of preserving isolation, even  among Ashkenazim.  This is definitely confusing because Jews came to Europe around 2000 years ago from Near East and analyses I have made using present-day samples show non-European admixture for Ashkenazim.  Very likely they have become more mixed lately in Europe and turning out to be like Neolithic Europeans, huh unbelievable.     (I have nothing against Ashkenazim people, my son-in-law is according 23andme's  test 98% Ashkenazi).

Another thing creating confusion is using Bedouins as a proxy for something.  Maybe it is not clear that Bedouins don't represent all Middle-Eastern migrations to Europe and are only an arrangement and substitute something that explains something in history, but real migrations has modified our genes many times more.  It is okay if  three or four ancient migrations can explain things, but it doesn't explain later migrations, possible from North Africa, Near East, Turkey ...  So Near Eastern Bedouin-like admixture can be Turkish as well, if we want to find out the history. 

My last observation belongs to Nganassans.   Almost all Europeans show in this study admixture with Nganassans.  They are a small isolated group in northernmost Siberia.   Although it is clear that also they are thought to be proxies, it is also quite suprising to see 2.8% Nganassan admix among French people, with almost lowest resnorm.  Does the resnorm mean in this case an error rate of 5% or more?  My conclusion is that Nganassans have Northeast European admixture, which is not observable using admixture analyses because they are a rather homogeneous group.         


2 kommenttia:

  1. Nganassans could be related to the ANE ?

  2. I have not tested it, but it is very possible. However, I have seen many times how isolated and homogeneous groups tend to seize the control of certain admixtures in standard unsupervised admixture analysis. This is very likely the reason why Nganassans became as a part of admixture tests, researchers made a conclusion based on std admixture analyses that they are good proxies for Siberians. This happens only in standard admixture tests, like in those ran by Admixture ( while qpAdm works differently. QpAdmin compares straight genomes to each other using f4-statistics and do not use chained process like Admixture, so qpAdmin shows more realistic results, although can be misled by reference populations. So qpAdm reveals an error that has been earlier made using problematic analyses.