A few people have asked me about a new paper on arXiv, The Missing Link of Jewish European Ancestry: Contrasting the Rhineland and the Khazarian Hypotheses. Since it is on arXiv you can read the preprint yourself. And, since it is a preprint it is not quite polished, so keep that in mind when evaluating it. After a fashion we are part of the polishing process. So what do I think?
First, it seems to me that the author has a sense of humor about this, and I don’t know how seriously to take some of his assertions. Consider this passage: Such an unnatural growth rate (1.7-2% annually) over half a millennia, affecting only Jews residing in Eastern Europe is commonly explained by a miracle (Atzmon et al. 2010). Unfortunately, this divine intervention explanation poses a new kind of problem – it is not science. Taken literally this seems rather bizarre. In the paper referenced the author refers to the “so-called demographic miracle of population expansion,” alluding to another scholar’s observation. It seems obvious that miracle in this context simply means an inexplicable phenomenon, not a genuine supernatural intervention. There are also plain factual problems which I assume will get cleared up in the final draft. Romania and Hungary are referred to as Slavic nations which were targets of migration by Khazars fleeing the collapse of their polity. Neither of these nations were then, or are now, Slavic. In general I have to say that the historical framework of the paper is very skeletal, verging on incoherent (at least to me).
I know I excoriate readers of this weblog for being stupid, ignorant, or lazy. But this constant badgering does result in genuinely insightful and important comments precisely and carefully stated on occasion. I put up my previous post in haste, and when I published it I wasn’t totally happy with the evidence from which the authors adduced that Ashkenazi Jews were not inbred. Here’s why, from the comments: Doesn’t identity-by-state permutations test reflect a counterbalance of admixture vs. inbredness + drift? Rather than just the degree of inbreeding? Since the population has strong admixture effects, a low IBS doesn’t exclude strong inbreeding, does it?
From my little personal experience IBS is not the best statistic from which to generalize widely, and can be highly misleading in admixed individuals, as implied by the commenter. First, since I’ve stated above that the Ashkenazi Jews are admixed, let me go into a tangent as to why Ashkenazi are admixed between a Middle Eastern and Western European population, as opposed to being a relatively unadmixed ancient Eastern Mediterranean group with affinities to both regions. The previous previous paper found evidence of linkage disequilibrium decay. This means that LD was high in admixed individuals in the past, and declined over time. Why?