Iberia: your genes are riding up on one side

I’ve been sitting on this paper for a while, hoping I could get some geneticist to collaborate on the write-up, because while I recognise enough of the words in genetics at least not to fall off when the argument goes round corners, I certainly can’t evaluate whether it’s soundly based or not. Simon Ford back at Clare in Cambridge gave it a once-over and thought it basically sane, though—and my thanks to him—and the point has come to write about it. Please bear in mind that I am not an expert in this stuff and would welcome any corrections or different perspectives, and read on. The work in question is a paper with twenty different authors that appeared in the American Journal of Human Genetics for 2008 entitled “The Genetic Legacy of Religious Diversity and Intolerance: Paternal Lineages of Christians, Jews, and Muslims in the Iberian Peninsula”.1 What it does is to take samples of the DNA of 1140 people from all over modern Spain and Portugal and compare them to similar datasets from Morocco and Tunisia plus an independently-derived average one for Sephardic Jews. The point of all this is the historical context that the Iberian Peninsula has, for a lot of its history, had a considerable Jewish population (`Sephardic’ actually comes from the Hebrew for Spain, ‘Sefarad’) and, of course, between about 710 and 1610, a fairly significant Muslim one that was ruling most of the area for most of that time. And, despite the fairly pompous title, what this paper does is compare what they consider to be the known history of the peninsula with the current genetic traces of population admixture.2

Haplogroup Distributions in Iberian, North African, and Sephardic Jewish Populations

"Haplogroup Distributions in Iberian, North African, and Sephardic Jewish Populations." "Sectors in pie charts are colored according to haplogroup in the schematic tree to the right, and sector areas are proportional to haplogroup frequency."

And these are, in a sense, the results. You have to realise, before you start to read this thing, that we are in a game not of certainties or clear causation here but rather of statistically significant correlation. So, you will notice that the three African samples (which they got from elsewhere3) are dominated by haplogroup E3b2 (and I’m not even going to try and explain what a haplogroup is; I would just have to copy it from a better explanation like this one anyway) but the Iberian ones are dominated instead by various branches of R1. This doesn’t stop each of those groups having some trace of the other one’s dominant element, because these things occur throughout most of humanity by now, and the question is not usually down to a single genetic signature like the ‘Cohen gene’ but to a pattern being convincingly like another pattern. If you compare it to the Sephardic Jewish signature at top right (again, from elsewhere, on this occasion a separate survey by two of the authors whose data is only given as supplemental information online4) you’ll see that there the significant marker seems to be the balance of groups G, J2 and all other J groups, which is a bit harder to spot. So, rather than just try and spot colour matches it seems worthwhile to say what the paper’s authors think they’ve found, given that they have crunched this data in a number of other ways that don’t make such colourful images, and then remark on that. Their conclusions were, roughly:

  1. Obviously, the Gibraltar Straits do mark a genuine divide in the make-up of the populations, which is not to say that there’s no common blood (ultimately, after all, we’re all cousins) but that there is a statistically significant (and fairly obvious) difference.
  2. The Basque country and Gascony have a strong showing from haplogroups that barely show up elsewhere (R1b3f, otherwise only strongly represented in Catalonia and the Balearics, weirdly; R1b3d; and in the Basque Country proper, R1b3b, which actually doesn’t show up anywhere else on the plot except for a sliver in North-West Castile, although I wonder if the big sample size there might not be something to do with that) and are also statistically quite different because of that.
  3. In the peninsula overall, admixture from an African-type parental population appears to be 10·6%, but this varies widely; there is none in the Basque zones, but 21·6% in Castile, i. e. twice as much as elsewhere.
  4. Admixture from a Jewish-type population is rather higher, 19·8% overall, but again with variation: none at all in Minorca, but 36·3% in Southern Portugal.
  5. The diversity of haplogroups within the dominant one from Africa is lower in the Iberian Peninsula than in Africa, suggesting that only a subset of the African population as it now is is represented in the peninsula’s genes.
  6. Contrariwise, the diversity of the Jewish sample in the Iberian population is higher, suggesting a longer-term admixture (though see below).
  7. The African sample is represented, not as one might expect most strongly in the south around Granada and least strongly in the north, but rather in the west, especially Castile and Galicia, that is the furthest parts north of the west, as well as also in Minorca which is less surprising maybe.5

Some of this makes perfectly good sense with what we know of the demographic history of this area, although it does persistently have to be borne in mind that we are talking about a history covering all of the last, say, three thousand years, piled up and indistinguishable. There is some possibility of distinguishing chronology with such evidence: as the authors say, the low diversity of the African sample in the Iberian peninsula compared to the Jewish or African-local ones suggests that it arrived more recently than the others because it has presumably had less time to spread and average out. But this is not ‘proving’ the Muslim conquest from genetics or anything; it is noticing a particular phenomenon that the conquest we already knew about provides an obvious explanation for. Likewise, the strong Jewish signal in South Portugal is odd until you consider that Portugal, unlike Castile or Aragon-Catalonia, didn’t expel its Jews and therefore picked up quite a lot of exile population from the reconquered areas of those two kingdoms, i. e. the south, in the fifteenth century, who have presumably left some trace in the genepool since then. On the other hand, the western-side bias of the African signal is very strange. It is certainly true that Muslim settlement, for most historians at least, is unlikely to have been substantial outside of Córdoba’s immediate zone of control, and we can do quite a lot about suggesting from place-names which groups wound up where.6 That would explain the low signal in Catalonia, but it patently conflicts with the high signal in Galicia. The authors suggest that this is down to the forced relocation of the morisco populations to the north and west after the war of 1567-71,7 and so indeed it may be—we have to watch that we don’t immediately conclude “OMG settlement in 711!” from this data given that it also includes all movements since—but if so it seems very strange to me that the areas where we know Muslims were for longest show less of a trace, and that suggests that the incomers were distinctive and also didn’t mix very much, whereas the moriscos blended into the wider population much more.

Horseshoe arches in the Leonese church of Santiago de Peñalba

Horseshoe arches in the Leonese church of Santiago de Peñalba, another kind of evidence for cultural admixture, more or less contraindicated by the genetic evidence

There are also three problems with their conceptual framework that I see which I think need discussion. The first, they have anticipated and headed off, although they don’t phrase it quite as I would, which is that if this Jewish signal prototype they have is already based on Jews from only this area then inevitably, you’d think, it is going to be much more admixed with Iberian material than a sample of a population outside Spain. In other words, there is a risk here of concluding, “Iberian Jews… are quite Iberian“, what is somewhat less exciting than the assertion “Iberian populations surprisingly Jewish”, which is more like what the paper actually says. The authors were not worried about this, as far as I can tell, but were concerned that the self-identification of the Jewish population that was used to obtain the sample on which they relied, i. e. the DNA of people who think they’re Jewish by descent, might well be less exclusively Jewish than those people thought. The counter that they have to this also works for my worry, however, it being that there are within that Jewish sample, as well as quite a lot of haplotypes shared with Iberian populations, three or four that are not but do match strongly with the Middle East. So, as long as they aren’t Greek or Phœnician (the long time-frame again), which seems unlikely given that they are as strongly visible in the West as the East, that does show some genuine Semitic ancestry to the sample group.

Iberian, North African, and Sephardic Jewish Admixture Proportions among Iberian Peninsula Samples

"Mean North African, Sephardic Jewish, and Iberian admixture proportions among Iberian samples, based on the mY estimator and on Moroccan, Sephardic Jewish, and Basque parental populations, are represented on a map as shaded bars on bar charts. Error bars indicate standard deviations, and three-letter codes indicate populations, as given in Figure 1."

That takes us straight to the second problem, though, which is one of missing populations. I am broadly happy that most of the Muslim army of 711 and subsequent settlement was probably composed of Berbers and other Africans (even if allegedly some of them might have been Vandals by descent…), I think this is one of the things that Guichard’s work makes acceptable, but nonetheless they weren’t all Berbers, there was an actually-Arabic presence in the officer corps, because we know some of them by name, and of course there was also a massive civil war in 741 kicked off, as the chronicles of the time (at least, compared to the chronology of the genetic evidence) see it, by a fresh wave of settlement direct from Syria.8 So it seems to me that when we see a Middle Eastern genetic sample, it doesn’t have to be Jewish, and that ideally there would be some way to check this sample for what might be a tiny tiny Arabic representation, but might not (and it would be really nice to know which and where).

The bronze inscription of Botorrita, in eastern Ibero-Celtic characters

The bronze inscription of Botorrita, in eastern Ibero-Celtic characters

Then there is another missing population, which is the actual Iberians. Quite early on the authors decide that the best comparator for the African and Jewish samples is the Basque one, as it shows no or little mixture with those groups, so everything else in the peninsula is then thought of as being more or less of a mixture between the three `parental’ samples. Well, OK, but whenever the Basques arrived in Spain, other groups followed, most obviously the Celtic groups we now call Iberians, and also maybe some Visigoths, you know, though we don’t seem to credit that those were numerically significant any more.9 I don’t think it diminishes the significance of the African and Jewish samples being different in the ways that they are too much, but I think that a better conceptual model might have been instead to take a total average of the peninsula and emphasise differences from it globally, rather than thinking in terms of `amibasqueornot’. Or, again, perhaps it would just be nice to have had some potential Celtic (or even Gothic) comparators factored in too so that we might get some sense of where those groups might have been best preserved, if they are at all. The paper’s only 11 pages long, after all, though I realise that I may just have idly asked for about three or four more years’ computing and sampling.

Interior of Santa María la Blanca, Toledo, previously a synagogue built in Almohad style

Interior of Santa María la Blanca, Toledo, previously a synagogue built in Almohad (i. e. a Berber Muslim) style. From Wikimedia Commons

So, in short, this stuff is really interesting but it’s very difficult to distill it down to historical events without essentially using what we already know to explain this new data. I get a certain kick out of knowing that some of the more traditional Reconquista-minded scholars would have been horrified to think that heroic Castile was actually more African and more Jewish than other areas of the peninsula but, if that’s down to post-reconquest resettlement by the kings, that becomes less of a delicious irony and more likely to be a reflection of the fact that populations who feel their identity may be dissipating are more likely to stress it aggressively. I think that these samples could actually be interrogated to tell us more about the settlement period by, for example, adding Arabic and Celtic comparators (if the latter can really be assembled, given how vague a group `Celtic’ populations are when considered historically10). At the moment, though, the main early medieval takeaway from this, which is what I at least am really interested in, is that it looks to be demonstrable that the African settler groups who (probably) arrived with and after the Muslim conquest really didn’t mix very much with the local populations. That’s not nothing, but I would still like to know if we might some day be able to guess at how much of the settling population they were from this kind of data, and thus guess also at the change in the élite too.

1. Susan M. Adams, Elena Bosch, Patricia L. Balaresque, Stéphane J. Ballereau, Andrew C. Lee, Eduardo Arroyo, Ana M. López-Parra, Mercedes Aler, Marina S. Gisbert Grifo, Maria Brion, Angel Carracedo, João Lavinha, Begoña Martínez-Jarreta, Lluis Quintana-Murci, Antònia Picornell, Misericordia Ramon, Karl Skorecki, Doron M. Behar, Francesc Calafell and Mark A. Jobling, “The Genetic Legacy of Religious Diversity and Intolerance: Paternal Lineages of Christians, Jews, and Muslims in the Iberian Peninsula” in The American Journal of Human Genetics Vol. 83 (Bethesda 2008), pp. 725-736, DOI 10.1016/j.ajhg.2008.11.007 (open access). Twenty authors seems like enough, really, although I can’t help feeling that they could also have credited the historian they consulted with (see below) and, after all, this is very far from the most extreme case of multiple authorship I can think of.

2. For the known history, they appealed to Dolors Bramon (ibid. p. 734, Acknowledgements), who is the current expert on what is to be learnt about Christian Iberian history from Islamic sources; her little anthology, De Quan Erem o No Musulmans: Textos del 713 al 1010. Continuació de l’Obra de J. M. Millàs i Vallicrosa (Vic 2000), is a frequent source of great help to me. So that was an unusually good choice, really, but apparently not a research contribution. Hmph.

3. Adams et al., “Genetic Legacy”, p. 727, citing E. Bosch, F. Calafell, D. Comas, P. J. Oefner, P. A. Underhill and J. Bertranpetit, “High-resolution analysis of human Y-chromosome variation shows a sharp discontinuity and limited gene flow between Northwestern Africa and the Iberian Peninsula” in American Journal of Human Genetics Vol. 68 (Bethesda 2001), pp. 1019–1029, and B. Arredi, E. S. Poloni, S. Paracchini, T. Zerjal, D. M. Fathallah, M. Makrelouf, V. L. Pascali, A. Novelletto and C. Tyler-Smith, “A predominantly neolithic origin for Y-chromosomal DNA variation in North Africa”, ibid. Vol. 75 (2004), pp. 338–345.

4. Adams et al., “Genetic Legacy”, p. 727 and describing work by Doron M. Behar and Karl Skorecki; the data is tabulated in the online version of the paper as “Haplogroups and Y-STR Haplotypes of Iberian Peninsula and Sephardic Jewish Samples” here (PDF).

5. Here as elsewhere, the sample from Asturias is just too small to allow significant conclusions, which may be just as well considering how much that one would expect is missing from it. This gives me pause, again, about drawing conclusions too far from the other areas with proportionally lower representation in the samples, including not least Minorca of course.

6. For the somewhat localised nature of the Andalusi state, I am used to citing Eduardo Manzano Moreno, La frontera de al-Andalus en la época de los Omeyas, Bibliotheca de Historia 9 (Madrid 1991), though I had the great pleasure of meeting the author this week and he tells me that he would now revise most of it! Extremely frustrating, as I have come to see it as canonical, which may be exactly why he would like to change it. Anyway. For place-names and settlement, the work of resort is by Pierre Guichard, either in French as Structures sociales « orientales » et « occidentales » dans l’Espagne musulmane (Paris 1977) or trans. into Castilian & rev. as Al-Andalus. Estructura antropológica de una sociedad islámica en Occidente (Granada 1998), though Dr Manzano tells me this too must be considered obsolete now. I don’t know if I’d agree there (or, it turns out, with quite a lot else Dr Manzano would argue, which was fun; more on this in due course). Compare Jessica A. Coope, “Marriage, Kinship, and Islamic Law in Al-Andalus: Reflections on Pierre Guichard’s Al-Ándalus” in al-Masaq Vol. 20 (London 2008), pp. 161-177, which is interesting because it disagrees with Guichard in exactly the opposite direction to Dr Manzano. For an English introduction to these issues, albeit a controversial one, see Roger Collins, The Arab Conquest of Spain, 710-797, History of Spain 4 (Oxford 1989). Collins caught it from the critics here because he effectively refuses to use Arabic historical writing, reckoning it all far too late and legendary to be anything other than misleading. There is also, of course, the fact that he doesn’t read Arabic, and this makes him an easy critical target because of course how can he know what he’s missing? but if you compare the exactly contemporary and much more traditional ‘Abdul Wahid Dhanun Taha, The Muslim Conquest and Settlement of North Africa and Spain (London 1989), I would say that it is fairly clear that Collins had a point. The fact that we can get three books like Collins, Taha and Guichard all purportedly telling the same story and disagreeing so incredibly (to say nothing of Manzano’s Frontera) is a measure of how charged these debates are. Without that charge, after all, how could we ever have had the now-legendary Ignacio Olagué, Les Arabes n’ont jamais envahi l’Espagne (Paris 1960, 2nd edn. 1973), to which cf. Pierre Guichard, “Les Arabes ont bien envahi l’Espagne : les structures sociales de l’Espagne musulmane” in Annales : Économies, sociétés, civilisations Vol. 29 (Paris 1974), pp. 1483-1513. I may have become sidetracked here.

7. Adams et al., “Genetic Legacy”, pp. 732-733.

8. Testified to even in the Christian Chronicle of 754, also known as The Mozarabic Chronicle though `Mozarab’ is one of those words that means too many things and should be retired, as translated in Kenneth Baxter Wolf, Conquerors and Chroniclers of Early Medieval Spain, Translated Texts for Historians 9 (Liverpool 1990, 2nd edn. 1999), pp. 111-160 with commentary pp. 25-42, cc. 82-86 in which the chronicler helpfully tells us that he wrote a whole book about this already so won’t repeat himself here. Do we have the book? No, we do not. Ah well. Nonetheless, it is this proximity to events that caused Collins to favour Christian sources over the Arabic ones. On the difficulties with the term `Mozarab’, see Richard Hitchcoock, Mozarabs in Medieval and Early Modern Spain: identities and influences (Aldershot 2008), passim but esp. pp ix-xx.

9. Roger Collins, Visigothic Spain 409-711, History of Spain 3 (Oxford 2004), pp. 25-26.

10. On which you can see the brief and bracing statements of Guy Halsall, who risks Godwin’s Law at an early stage of a book by comparing Celticism to Germanism in his Barbarian Migrations and the Roman West, 376-568, Cambridge Medieval Textbooks (Cambridge 2007), pp. 24-25.

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39 responses to “Iberia: your genes are riding up on one side

  1. Uh-oh. I’ve just read two good articles (IMO) related to this; “Vascones and Visigoths: Creation and Transformation of Identity in Northern Spain in Late Antiquity,” by Scott de Brestian and “Text, Artifact and Genome: The Disputed Nature of the Anglo-Saxon Migration into Britain”, by Michael E. Jones. Both are in Mathisen and Schanzer, eds., Romans, Barbarians, and the Transformation of the Roman World. Surrey, UK: Ashgate (2011). de Brestian discusses some aspects of ethnogenesis related to the Basques and Jones really gets into methodological issues with working backward from DNA samples and genetic patterning of modern populations as opposed to archaeologically recovered DNA. No way I can get to those today but maybe I can put something up next weekend, I’ll add a comment here if I do.

    • Aha, both very interesting-looking references, and when we have the volume in libraries here I will be sending students at the latter. I must have a look at the former myself and should probably target the volume at Leeds. Thankyou!

  2. I know you said you weren’t going to discuss what a haplotype was, but to add to your ‘worries’, I’d just like to point out that the authors were only using Y chromosome haplotypes, which means they are only sampling half of the population, and their data are *by definition* incapable to telling you if the distribution of ancetors in females over the intervening centuries is similar… And it is by no means certain that this is the case (see for example, “Identification of population substructure among Jews using STR markers and dependence on reference populations included”, http://www.ncbi.nlm.nih.gov/pubmed/20546593 @ p.2 / 15). But you’re right about another 4 years of computing, etc…

    • That much, I had gathered (mtDNA and so on, yes?), but yes, I could have added it into the post without costing more than a line or two, fair point. It is indeed another worry, although again if there were a significant difference there between African and Jewish signals that might say something important about the type of entry into the genepool performed by the two groups. I mean, if the signal for the African types only really showed up in y-chromosomal DNA then it would look much more like a military settlement rather than a migration. Still undatable of course!

      • Well, quite! Which is why it’s a shame they didn’t include the mitochondrial… or at least perform a follow up study of same (I couldn’t find any evidence of this on PubMed).

        • There’s various mtDNA work on other samples done by various members of the team lurking in footnotes, but not done from this data as far as I can see. I think what we’re getting at is that we have numerous extra ideas for the team’s follow-up work :-)

  3. Two comments:

    1) The title: to equate ‘Iberia’ with the geographic peninsula it’s a misleading roman concept (s.II-III bc). In origin (s.VI bc) Iberia was the greek term for the people/culture moreless from Rhone to past Ebro, followed periegetically by the turdetanians, (hercules colums section), and the celtic atlantic shore on the ocean.
    2) The contents: mixing genetics and culture (ie: ‘jewish’) is … well … weird.

    • Last first, Jewishness is at least biologically defined and they’re not interested in the culture in this study. I have littered the post with buildings mainly to indicate that biology is not the whole story, but I think they’re safe enough with their categories.

      As for the former, well, yes, but Spain, which I took out at the last minute, would be worse. I was at a conference on Friday, sat next to a Catalan, where someone described a phenomenon affecting `Spain’ being instanced at Lisbon, which has of course never been part of an entity called Spain/España/Espanya. So what would you rather? `Iberian peninsula’ is the most accurate workaround but would have been very clumsy in this title.

      • I am sorry, but I don’t get-it. Acording to the abstract, has involved the long-term residence of two very different populations with distinct geographical origins and their own particular cultural and religious characteristics—North African Muslims and Sephardic Jews.

        So they think that sephardic jews came from out of the iberian peninsula!?
        Or that africans only came since VIII ac century!?

        ‘Jews’ are documented since pre-cristian times, ‘Africans’, since Argantonio’s time. Weird.

        • Sephardic Jews are by definition Iberian ones, aren’t they? So, yes, that’s where the sample comes from but the assumption is that at some point this gene source immigrated. Then, the difference in the way that that sample has spread and diversified and the African one, as they define that, hasn’t, indicate some difference of chronology between the two arrivals. As I say, this is not really proving the history with genetics; it is showing things in the genetics that we can explain using known history. But it also shows some things that are harder to explain thus, and that’s why I find it interesting.

        • Joan – the full article has considerable discussion of the definition of the Sephardic comparator population: they were men who declared at least 2 previous generations of Sephardic male ancestors who were living in regions of Europe that received immigrants from the Penninsula after the expulsion of the Jews, and did not have significant recorded Jewish populations prior to that (which might have provided a confounding genetic signal). There are obviously difficulties when combining ‘biological’ and ‘cultural’ definitions, but they’ve done a reasonable job at 1) recognising the problem, 2) trying to ‘control’ for it, and 3) reporting their approach openly. The 3-generation definition has been validated in other genetic studies as a pretty adequate (i.e. statistically satisfactory) measure.

          As for dates – the nature of haplotype work is a little bit like codicology – by deducing which ‘errors’ were introduced into the ‘text’ earlier than others it is argued that certain ‘versions’ of the text appeared earlier than others. So ‘errors’ that are in *every* copy, probably came from a common original, while those that only appear in a few copies, were probably introduced by later ‘scribes’. This is why they’ve included recent genetic data taken from – for example – North African groups: because by comparison they ought to be able to say whether the signals considered ‘African Muslim’ in their Iberian sample are likely to come from recent or more ancient migrants… but having said that, the temporal resolution is still not terribly precise.

  4. Da-yum, as we say here. On the LSAT, this test I am trying to study for, they would take this study and ask questions about the implicit logic or gaps in reasoning in the conclusions it draws, or doesn’t, or appears to draw. I am glad they won’t have this to work with because there are too many x-variables, I would never be able to figure it out.

  5. …and that Leonese church is brilliant, and I have not been to it.

    This isn’t in your field but here’s a new and from what I can gather, great and ground breaking book on ‘hybrid’ cultural production: http://undpress.nd.edu/book/P01392 … the obliquely related point being that he starts by pointing out that mestizo culture (in colonial Alto Perú) was not made by mestizos (general implication, cryptically stated: one is not what one is).

    • Ooh, I’m interested in cultural hybridity, that’s why I like the frontiers, and I know also an anthropologist who will be interested. But one is never wholly what one is, surely: one’s identity is always partly provided by others. It’s part of growing up/social conditioning.

      If one is a building, of course, then one’s identity is wholly constructed, although by both designers and users. (Why do you and I keep anthropomorphising buildings in conversation?) And no, I haven’t been to Peñalba either. If I get into that part of Spain ever I have to start with Oviedo, but León and its environs are close behind on the list. And the mad churches on the Duero that face off against Muslm refuge fortresses! So many churches, so little time…

  6. highlyeccentric

    Ooooh. *peers* I don’t think I understand more than half of that, but oooh, shiny!

  7. Another Damned Medievalist

    A couple of other things come to mind: first, um … Rome? How do they figure in the pre-Visigothic and pre-Vandal populations? After all, it’s not as though Iberia went from something Celt-ish to OMGgoodthingtheVisigothscameandleftnotrace! (sorry for any weird formatting – iPad is showing me how useless it is – stupid POS)

    But yeah — so what exactly is an Iberian when it’s in the genes?

    Second thing: how the hell can you examine a population for Jewishness with any accuracy if you are partially relying on self-reporting (and by the way, did they look at the populations from Istanbul, because that ought to offer good comparisons?) and not look at maternal DNA? Because, well, …

    Just curious.

    • Gawd, how did I forget the Romans? I probably have to edit that in with suitable claims of idiocy. I’ve no idea how one would pull together an Iberian `signal’, however, because presumably it would be a subset of Celt and I’m not sure that really existed, as genetics rather than as culture group.

      As for the Jewish section, though, because this seems to be what everyone is confused by and no-one wants to go and read themselves, here is what they say:

      Comparative data for Sephardic Jewish populations were extracted from a large collection of Y haplotypes assembled by D.M.B. and K.S. The term “Sephardic Jews” is used here in its narrow sense, referring to Jewish men deriving from originally Ladino-speaking communities that emanated directly from the Iberian Exile. Included males noted in their informed consents that they, their fathers, and their paternal grandfathers are Sephardic Jews from the specified community. A sample of 174 males was compiled (Table S1 ), made up of self-defined Sephardic Jewish males either from the Iberian Peninsula itself or from countries that received major migrations of Sephardic Jews after the expulsion of 1492–1496, as follows: Belmonte, Portugal (16); Bulgaria (49); Djerba (13); Greece (2); Spain (3); Turkey (91). Countries that received exiles from the Iberian Peninsula but that themselves had substantial preexisting Jewish communities (Italy and the North African countries) were not included. Haplogroups were equivalent to those typed in the Iberian Peninsula samples, except that sublineages of hgR1b3 were not defined. In haplogroup comparisons, therefore, all of these sublineages were combined into hgR1b3 (also known as R-M269) itself. Data on eight Y-STRs were available, allowing comparison with Iberian and North African data.

      It is important to consider factors that might act to elevate the apparent proportions of Sephardic Jewish ancestry that we estimate, because these values are surprisingly high. Choice of parental populations in admixture analysis can have a major effect on the outcome, and among the parental populations in our analysis, the Sephardic Jewish population has a different status compared to the two others: whereas Basque and Moroccan samples are drawn from sizeable populations that have maintained their existence in situ, with a probable low level of admixture with the other parentals, the Sephardic Jewish sample is taken from a comparatively small group of self-defined individuals whose ancestors have lived in various parts of the Iberian Peninsula and were themselves probably subject to some degree of admixture with Iberians. This potential past admixture would have the effect of increasing the perceived level of Sephardic Jewish ancestry compared to the actual proportion. The presence of the typically western European lineage hgR1b3 at a frequency of 11% in the Sephardic Jewish sample might be a signal of such introgression. To examine this, we constructed a network of hgR1b3 Y-STR haplotypes in Iberian, Sephardic Jewish, and Moroccan samples (Figure 6). Twelve of the 20 Sephardic Jewish R1b3 haplotypes are shared with Iberian examples, suggesting that they will indeed affect the admixture proportions. However, eight of the 20 are unique, and five of these are peripheral in the network. They will have little impact on the admixture proportions, and they probably reflect R1b3 chromosomes of Middle Eastern origin. It therefore seems that, overall, the ancestry proportions are likely to be only slightly affected by Iberian admixture into the Sephardic Jewish sample.

      Now, I don’t know if that answers your questions, but that and the references linked off it are what I have to go on. At least, as I say, they have tried to check the self-reporting bias. My problem with their check is that I’m not sure it excludes any other Semitic Middle Eastern origins, but they have at least checked.

      As for the lack of mtDNA evidence, well, yes, that is a problem but also a different study. I agree that it needs to be done to complement this but I don’t think its absence messes with these results, just makes them harder to interpret. Perhaps I’m missing something?

      • Well, hmmm. What I had in mind was that there might be a significant number of people who do not self-identify as Sephardic Jews because their (fore)fathers married out or (more likely) converted. It seems to me that there might be some weird overlaps between those people and, as you point out, other people of Semitic Middle Eastern origins. And even those would seem to me to be rather fraught. I mean certainly, there is a fair amount of endogamy in the one group. But at what point do we mark that? Do we take the DNA of people known to be Jewish at the time of Christ and assume endogamy from there? Or do we mark it at the time of entrance to Iberia (and when was that, anyway?)…?

        • Well, this is none of it historic DNA (which is an issue in itself, but which would make it a very different and much smaller study). So the point of Jewishness for sample purposes has to be the present day. As you say, there are problems on both sides with that: the one that they identified with people self-reporting who are not strongly Jewish by biological descent, and the one you’ve just identified with the opposite, people who are so descended failing to self-identify. But it seems to me that both of those factors should tend to bring the Jewish and non-Jewish signatures closer to each other by reason of overlap, and so the fact that they are, nonetheless, clearly distinct, is significant. The mileage they then make out of the similarities that do exist may be problematic as a result, of course, but since most of that mileage is based on variation rather than a steady uniform presence, again… it must mean something!

  8. I would just like to say – and fairly strongly – that comparing celticism to germanism doesn’t bring me within waving distance of Godwin’s law. That is ill-informed and not a little cheap.

    • Sorry, Guy, no offence meant; I was thinking in the spirit of this XKCD cartoon if anything, I suppose, not looking for a political point. Possibly where I’m ill-informed is in thinking of Godwin’s Law as funny; the link I put under the phrase in that footnote does, I would have to admit, suggest that Godwin’s actual purpose was a bit more serious.

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  10. That’s absolutely riveting stuff. Let’s hope they do dig further into the ‘amibasqueornot’ Iberian/Basque debate; I’m slavering for the update!

  11. ¡Jewish in Asturias! sorprendente. Sabemos por las crónicas altomedievales de la presencia de esclavos musulmanes capturados -la mayor parte hispanos convertidos al islam y algún beréber- y puestos al servicio de los monasterios y de la alta nobleza. Durante mucho tiempo no se les permitió mezclarse con el resto de la población a pesar de ser ya cristianos hasta que ya en la baja Edad Media la barrera racial se fue diluyendo.
    En cambio no hay prácticamente presencia judia salvo una pequeñísima comunidad en Oviedo y creo que también en Cangas del Narcea.
    Aunque la muestra no es muy representativa por el número de personas utilizadas habria que tener también en cuenta que en la actualidad Asturias es una región con un porcentaje de población de otros orígenes enorme por la industrialización del siglo XIX vinculada a las minas de carbón y la siderurgia y acentuada en el siglo XX por la creación franquista de grandes conglomerados industriales INI.
    En ese sentido hoy en dia una parte importante de población asturiana desciende de leoneses,gallegos, extremeños y portugueses por este orden.
    Esta gran emigración curiosamente se produjo cuando muchos asturianos por motivos políticos durante el franquismo y por la gran tradición de emigración de gallegos y asturianos aún seguían marchándose a América (Cuba, Argentina,Méjico) y a Europa (Bélgica y Suiza). Dicho esto quiero aclarar que no tengo ninguna hostilidad ni hacia los judios ni hacia los norteafricanos que son parte importante de la historia de España y en el primer caso de toda Europa.

    • Creo que usted ha identificado los dos problemas de la conclusión de que los datos parece indicar aquí, Neville. En primer lugar, la muestra asturiana es muy pequeña, demasiada pequeña para decidir si es o no significativa. En segundo lugar, existe el problema que utilizamos las poblaciones modernas, con todos sus cambios desde la época altomedieval. Hay un proyecto británico llamado Blood of the Vikings, que tuvo problemas similares en regionas que habían sido fuertemente industrializadas. Que superado el problema para tomar de muestras solamente de personas que llevaban los apellidos que se han documentado en los registros fiscales de la zona del siglo XVI, y así se produce un resulto mucho más clara. No sé, sin embargo, si talos registros existen en Asturias, y, por supuesto, esto sólo se puede hacer con el ADN de los hombres.

  12. Lamentablemente durante la revolución obrera de 1934 http://es.wikipedia.org/wiki/Revoluci%C3%B3n_de_1934#La_Revoluci.C3.B3n_de_Asturias las iglesias de la región fueron quemadas en gran parte perdiendose información muy valiosa relativa a los nacimientos aunque los apellidos asturianos son claramente reconocibles salvo los terminados en ez (Suárez, Álvarez, Menéndez) y la mayor parte están consignados en los registros de hidalguía ya que hasta el siglo XVIII casi toda la población de Asturias, Cantabria y otras zonas del norte era considerada hidalga o de “sangre limpia”. Es conocida ya desde hace mucho tiempo la característica braquicefalia de Asturias, Cantabria y Lugo frente al resto de la Península dolico-mesocéfala pero hay muchas teorías respecto al porqué de esta singularidad. Se ha estudiado el tema de los llamados “Vaqueiros de Alzada” un grupo “maldito” dentro de la población de Asturias pero parece que obedece mas a una cuestión socieconómica que de orígenes (pastores estacionales frente a campesinos). Creo que el estudio mas serio que se ha hecho es en la vecina región de Cantabria de orígenes étnicos muy similares a los asturianos aqui te dejo el enlace que está en inglés

    • Que es un documento muy interesante, Neville; gracias por el enlace. Se podría hablar a varios debates, no sólo éste sobre la presencia africana en ADN ibérico, sino también el viejo argumento de Barbero y Vigil sobre la continuidad extremadamente larga de las poblaciones norteños. Voy a tener que hacer un post de su propio en su debido momento. Gracias otra vez!

      (For those reading only in English, Neville’s second link goes to another paper (in English) in Annals of Human Genetics that analyses a quite localised population from Cantabria, which is right between that low-sample Asturian area in the Adams et al. paper above and the Basque one, and finds several odd things that are going, as with this paper’s findings, to take some explanation. I’ll have to do a separate post about this one!)

  13. Well, I don’t see why the Balearics could not very well have had some ancient population closely related to the population in the Basque country, etc. …. Nor why such traces of such a population — perhaps once upon a time or two more widespread in the region — might not show up more prominently in such a literally insular environment.

    • Well, yeah, that one sub-haplotype is kind of striped across from the Basque country through to the Balearics, and Catalonia still has a lot of Basque place-names in its northern reaches, so I don’t think there’s anything too surprising about that; what might be more surprising is the strong showing of R1b3f in Catalonia, which is basically the main road for any migration in either direction!

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  16. Medieval Rosa

    I just want to add that samples from colonial cities are entirely missing and that would add the group of converts who left.

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