Comments on: Abraham's genetic threads

By: Dm

Dm — Thu, 17 May 2012 14:25:20 +0000

#8 Ryan, Conversos didn’t “simply” become regular Catholics, there still had their separate identity partly by coercion, partly by choice. And soon, the Crowns moved to expel the Conversos and the Moriscos out of Iberia, ensuring that their contribution to the gene pool of modern Spain is small. The great expulsions brought most of the “recent converts” to North Africa, but many went to the Colonies too, resulting in documented traces of Sephardic admixture across Latin America and in South Asia.

As Razib recently discussed in Cuba threads, Middle Eastern and/or North African components of Cuban genotypes can’t be explained by a much smaller admixture in today’s Spaniards … but perhaps can be explained by the enrichment in Conversos and Moriscos in the early Colonial migration out of Spain and Portugal.

By: Paul Givargidze

Paul Givargidze — Thu, 17 May 2012 14:14:02 +0000

@ ryan: Dr. Ostrer and I traded a few emails a couple of years ago regarding the testing of Assyrians. I got the impression he was genuinely interested in including Assyrians as part of a future analysis of the Near East. So, hopefully, one day, we will see something from his team.

I would like to add three additional notes regarding possible Assyrian-Jewish genetic links, presumably from a very distant time in the past:

1. Genetic screening in the Persian Jewish community: A pilot study. Kaback et al. 2010

“Pseudocholinesterase deficiency…BCHE is the name for the genetic locus: an autosomal recessive condition common within the Persian and Iraqi Jewish populations.”

“Approximately 1 in 10 Persian Jews were found to be heterozygotes for a single point mutation in this gene.”

Based on the very limited number of Assyrians tested at 23andMe, carrier incidence in Assyrians for this condition may be similar to that observed in Iraqi and Iranian Jews. My mother and I included.

2. Screening for Carriers of Tay-Sachs Disease among Ashkenazi Jews — A Comparison of DNA-Based and Enzyme-Based Tests. Triggs-Raine et al. 1990

“Our DNA analyses of obligate carriers of Tay-Sachs disease identified all the common mutations known to cause the disease in the Ashkenazi population. The three known mutations accounted for 98 percent (61 of 62) of the mutant alleles in the group of Ashkenazi obligate carriers. The frequency of identified mutations increases to 99 percent (93 of 94) of the alleles of all patients and carriers, or to 99 percent (78 of 79) of the alleles of all patients with infantile disease, if other obligate carriers described in the literature are included. These mutations were not restricted to the Ashkenazi population, since the insertion mutation was found in four non-Ashkenazi subjects, and the exon 7 mutation in a non-Ashkenazi (described as Assyrian) patient.”

3. Possible Y chromosome links between Assyrian and Ashkenazi men (e.g. L943).

By: Razib Khan

Razib Khan — Thu, 17 May 2012 06:26:37 +0000

#12, they’d need to do some rather sophisticated analysis to discern what you are wondering about. the reason is simple: the authors argue that the substantial european admixture into ashkenazi and sephardic jews is from western mediterranean populations. this includes the iberians. so you need to trace IBD, but differentiate that IBD ~2,000 years ago, to IBD ~1,000 years ago. i know some researchers who are doing this with european data, and the time intervals are going to be very wide (and these are people with more computational resources than this team).

By: ryan

ryan — Thu, 17 May 2012 06:12:02 +0000

Well, as you know the relationship would likely be stronger with Sephardis than with Ashkenazim. I don’t draw any conclusions from the fact these authors didn’t report on any Iberian populations. They also didn’t report on Assyrian Christians, a population that your recent post suggested had quite close relationships to certain Jewish populations. I think there are things missing here, perhaps to intentionally emphasize discrete boundaries over continuities, though their aside about the Adygei and “populations not included” suggests less polemical intent. It does leave me wondering.

By: Razib Khan

Razib Khan — Thu, 17 May 2012 05:45:54 +0000

#10, popres data set has spaniards. if they found something they probably would have reported it. i ran IBS with ashkenazi jews once and other europeans. don’t recall them being that close to the ashk jews (though that’s a summary, not ibd).

By: ryan

ryan — Thu, 17 May 2012 05:40:14 +0000

I didn’t find any discussion of Spanish populations in Abraham’s Children. Basques are among the reference populations they look closely at, but I doubt that’s what you’re pointing me to. Are you referring to another paper or did I miss something in Abraham’s Children?

By: Razib Khan

Razib Khan — Thu, 17 May 2012 05:26:06 +0000

#8, see the paper.

By: ryan

ryan — Thu, 17 May 2012 05:25:12 +0000

What about in Spain, where there were repeated periods when people were forced into becoming conversos, some of whom kept their faith hidden (and may ultimately have rejoined Jewish communities elsewhere), but many others of whom simply became Catholics?

By: Razib Khan

Razib Khan — Thu, 17 May 2012 05:02:28 +0000

#5, random north europeans have jewish segments out of the blue. e.g., the pickrell affair. but it is a small number. not enough jews.

By: Razib Khan

Razib Khan — Thu, 17 May 2012 05:01:23 +0000

#5, random north europeans have jewish segments out of the blue. e.g., the pickrell affair. but it is a small number. not enough jews.

By: Tom Bri

Tom Bri — Thu, 17 May 2012 04:59:14 +0000

A question. To what extent do the non-Jewish populations in lands where Jews have lived for long periods, North Europe for example, show these same markers? I guess I am asking about the extent of outflow of genes from Jews to Gentiles, related to DM’s comment above.

By: John Emerson

John Emerson — Thu, 17 May 2012 01:01:08 +0000

Jews may not have wanted Hitler to know certain things, but Jews have traditionally believed that Jews are all kin.

By: Razib Khan

Razib Khan — Wed, 16 May 2012 17:51:52 +0000

#2, it’s cultural determinism. you’re confusing cause and effect. and #1 makes a good point. the jews of kaifeng disappeared in the 20th century in large part due to intermarriage. so the power of jewish nationhood in maintaining coherency is subject to an ascertainment bias.

By: Nihaya Khateb

Nihaya Khateb — Wed, 16 May 2012 17:21:56 +0000

“genetics is only part of the puzzle” , I am convinced rather the opposite. The fact that Jews are still a “race” and are forming a distinct genetic comunity is a strong proof for the fact that genetic determinism is still matter. The solid fact that it is very hard to strangers to enter the jewish comunity contributes to these data about genetic stability for 2500 years. Statistically, only minority of the jews out-bred with other nations, so the major genom was preserved.

By: Dm

Dm — Wed, 16 May 2012 17:19:02 +0000

Once Christianity and Islam marginalized the Jews, the gene flow from non-Jews to Jews diminished greatly
To presently extant Jews. The consequence of living in a diaspora for many generations, and at the same time being open to cultural and genetic inflows, is that one’s self-identification melts away as well. So there may have been a lot of strong inflows in some segments of the Jewish world, it’s just their descendants no longer identify as Jewish.

Back 2,500 + ybp, since the Jewish population remained to a large extent a local majority group, there was little “identity survival penalty” of higher admixture rate, and that’s why we still see a strong genetic footprint from those days.