Sephardic Jews DNA results

[Astur_Cantabri]

Sharp thanks!

Nice add to the paper.

Nevertheless this paper shows something different:



Share of Sephardim (conversos) in the current population, Asturias peaks enormously and E-V22 (with 4.44% next to Sicily) also peaks: the highest in Europe. No coincidence imho.

That paper is outdated and based on early/incomplete haplogroup data and flawed methodology. It basically extrapolates all instances of a haplogroup E to denote NW African admixture; all instances of haplogroup J to denote Sephardic admixture; and all instances of haplogroup R1b to denote local Iberian admixture. This was before downstream clade assignments were a thing. None of these proposed admixture ratios are reflected in autosomal findings or modern haplogroup data from any of these regions. NW African admixture averages between 2-5% in the mainland Iberian population and Sephardic admixture is not statistically significant be reflected in regional averages (though there are certainly individual samples that can be found).

The Asturias data, for example, is based on a sample size of 20 and assigns ‘North African’ admixture on the basis of positive calls for E3b and assigns ‘Sephardic’ admixture on the basis of positive calls for haplogroup J2 and G (the glaring flaws in this methodology should be self-evident). I suggest you take this 16 year-old study in its proper context.

I suppose you talks about NA markers as an global iberian average (maybe 4-5%). North African admixture in Iberia reach in some regions 9-10% ad máximum, for example Portugal, corresponding to last papers. Althougth we need more papers with more samples about it in future.

For sephardic origins, it would be more complex, the haplogroups are inssuficient, we must take in consideration haplogroups, autosomal genetics and historic records. To see the global impact in modern iberians don’t make sense, it’s clear that jewish converse population after 1492 was concentred in some regions (as I have said before), so the papers would should take in consideration specific regions according to historic records, even part of sephardic genetic some modern individuals could lose it… the sephardic ancestors and converse lived between 15th and 17th centuries, then they mixed with christian population and the incipient endogamy of precendent centuries was broken, we don’t inherit all markers of our ancestors, and the minoritary markers are the first that we lose through generations.

Having said this, let’s not divert the thread with NA genetics, NA theme is recurrent in Spain, but this thread is dedicated to Sephardim.

I agree that haplogroups are a wildly insufficient methodology from which to extrapolate any reliable figures for admixture — hence, my criticism of the 16 year-old study cited in this thread. The numbers I cited are based upon basal admixture results obtained by autosomal testing. The question of both NW and Sephardic admixture is a difficult one to pinpoint due to the diverse genetic character of both populations. 

I should have specified that basal NW African (i.e. Iberomaurusian) averages 2-5% in the mainland Iberian population. The figures could potentially skew a little higher, but would still likely oscillate around that baseline percentage, in my opinion. 

Furthermore, it’s difficult to assign any specific period or source population to the entirety of NW African admixture, as it has been present at low levels in the Iberian peninsula as far back as the Bronze Age — as is evidenced in multiple Iberian aDNA samples — and was present at statistically significant levels as far back as the Roman period. Regardless, it’s reasonable to assume that at least a plurality of the admixture present in the modern Iberian population is a result of Islamic-period diffusion, though I believe the absence of other basal Levantine and African genes in modern Iberians (that were carried by Islamic-period Berbers) further complicates the question. The same applies to the question of Sephardim ancestry, as there were other source populations (e.g., Phoenicians, Punics, Greeks, and Romans) that also contributed to the diffusion of comparable Eastern Mediterranean-shifted genes. 

Analysis would therefore have to incorporate an assortment of genetic factors into its methodology to arrive at sound conclusions — including deep clade haplogroup testing; testing the sorts of enclaves you mentioned, etc.)