posted
European Journal of Human Genetics (2010) 18, 1185; doi:10.1038/ejhg.2010.88; published online 23 June 2010
Chadic languages and Y haplogroups
Andrew Lancaster1
1Schrijnbroekstraat, Hasselt, Belgium
Correspondence: Andrew Lancaster, E-mail: andrew.lancaster@skynet.be
The January 2009 publication in this journal of an article entitled ‘Human Y chromosome haplogroup R-V88: a paternal genetic record of early mid Holocene trans-Saharan connections and the spread of Chadic languages’, by Cruciani et al,1 represents a major step forward in our understanding of the African Y haplogroup diversity and pre-history. Approximately one year ago I published a detailed review of the earlier studies in this field.2 Similar to Cruciani et al, a major theme of my consideration was the probable link between the dispersal patterns of Y haplogroups and Afro-Asiatic languages. In particular, although the major focus of that review was upon Y haplogroup E1b1b1 (E-M35), similar to Cruciani et al, I suggested that in the specific case of speakers of the Chadic family of languages, the high frequency of R haplotypes, which are otherwise uncommon in most of Africa, seems to be relevant for judging the strength of the competing theories regarding the origins of this language group within Afroasiatic. A comparison with this new publication can help put its findings into useful perspective.
In my review I proposed that the Y chromosomal evidence seemed to be most compatible with Blench's3 theory that Chadic is ancestrally most closely related to Beja and Cushitic, and arrived in its current position from the east and the direction of Sudan and the Red Sea. At that time, the data seemed to be much less compatible with Ehret's more novel position that it arrived from the north and is most closely related to Berber.4 A key consideration is that R haplotypes in various forms are generally Eurasian, being found as far away as Siberia, and their concentrated presence this deep in Africa has long been considered as evidence of movement of people from the direction of Levant, although the timing and route have been difficult to determine.5, 6
Blench's proposal that Chadic arrived with pastoralism involving goats, a way of life that spread from the Middle East, probably initially along the eastern side of the Nile, therefore matches the DNA evidence very closely. Furthermore, I observed, as do Cruciani et al, that the discovery by Černy et al of a mitochondrial link between Chadic speakers and the Horn of Africa (Mitochondrial haplogroup L3f) also supports Blench's position.7 In summary, I proposed that, in this case, a Y haplogroup had possibly been carried by a wave of innovation in life style (pastoralism), independently of language or overall genotype. As I remarked: The recent autosomal DNA study of Tishkoff et al. (2009)8 confirms that on the whole, Chadic speakers are more closely related to their Nilo-Saharan neighbours than to any other Afroasiatic group. Looking at the genome beyond Y-DNA these peoples show far less Eurasian ancestry that the Beja, for example.
Nevertheless, Cruciani et al argue that the discovery of V88 now demonstrates a strong Y chromosomal link between Chadic speakers and speakers of other Afro-Asiatic languages to the north of the Sahara. Their key evidence for this is their new data for Siwa in Western Egypt, a Berber-speaking area having approximately 27% R-V88 (93 people tested). These data are surprising and should be seen as one of the major discoveries of the article, and requiring an explanation such as the one given by the authors.
The article contains a striking contour map, which shows a coloured band of R-V88 passing from Siwa down to the Chadic speaking area, which would match Ehret's proposed migration route. However, analysis of the article shows that this coloured band simply joins two areas with high frequency, Siwa and the Chadic area. There are of course no data for populations along this band, which runs through the Sahara. One single population is therefore very important in their account. The potential importance of gaps in the data should be considered in several other directions also.
The study also contains no data for Sudan, which lies between the Chadic speakers in the west, and the Afro-Asiatic speakers in the horn of Africa and near the Red Sea. There are also no data for eastern Egypt. These areas are critical in determining whether Blench is likely to be correct, because they represent the path along which he believes pastoralism spread. Data for Sudan are limited but, as the authors note, the 2008 paper of Hassan et al does seem to indicate a potential presence of R-V88 there.9
We know from this and other studies that E1b1b1 dominates the Berber speaking area, leaving the Siwa result as quite surprising and unique. This in turn raises the question of what other surprising and unique populations may exist in other oases and unsampled regions.
With the limitations of the data in mind, it could perhaps be argued that Cruciani et al's hypothesis is strengthened by the similarity between their age estimate for the R-V88 clade and the time depth at which we know the Sahara was green, making movement in the area between Siwa and Lake Chad more practical. However, unfortunately, such age estimates are one of the most controversial parts of any study of this kind. Different estimation techniques are likely to give a wide range of possible answers.
References:
Cruciani F, Trombetta B, Sellitto D et al: Human Y chromosome haplogroup R-V88: a paternal genetic record of early mid Holocene trans-Saharan connections and the spread of Chadic languages. Eur J Hum Genet 2010; 18: 800–807.
Lancaster A: Y Haplogroups, archaeological cultures and language families: a review of the multidisciplinary comparisons using the case of E-M35. J Genet Geneal 2009; 5: 35–65.
Blench R: The westward wandering of Cushitic pastoralists. Explorations in the prehistory of Central Africa; in Baroin C, Boutrais J (eds): L'Homme et l'animal dans le bassin du lac Tchad. Paris: IRD Edn, 1999, pp 39–80.
Ehret C: The Civilizations of Africa: A History to 1800. Oxford: James Currey, 2002.
Cruciani F, Santolamazza P, Shen P et al: A back migration from Asia to sub-Saharan Africa is supported by high-resolution analysis of human Y-chromosome haplotypes. Am J Hum Genet 2002; 70: 1197–1214.
Luis JR, Rowold DJ, Regueiro M et al: The Levant versus the Horn of Africa: evidence for bidirectional corridors of human migrations. Am J Hum Genet 2004; 74: 532–544.
Fernandes V, Costa MD, Hájek M, Mulligan CJ,
Pereira L: Migration of Chadic speaking pastoralists within Africa based on population structure of Chad Basin and phylogeography of mitochondrial L3f haplogroup. BMC Evol Biol 2009; 9: 63.
Tishkoff SA, Reed FA, Friedlaender FR et al: The genetic structure and history of Africans and African Americans. Science 2009; 324: 1035–1044.
Hassan HY, Underhill PA, Cavalli-Sforza LL,
Ibrahim ME: Y-chromosome variation among Sudanese: restricted gene flow, concordance with language, geography, and history. Am J Phys Anthropol 2008; 137: 316–323.
Posts: 4021 | From: Bay Area, CA | Registered: Mar 2007
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posted
you cannot pinpoint the origin of E without ancient DNA from North Africa, Europe,Egypt,the Near, the Horn etc. Otherwise it's endless speculation and will never be certain
Posts: 42925 | From: , | Registered: Jan 2010
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posted
^You are just naive and don't understand rudimentary population genetics modeling. For instance, quiz question. In genetics, what are the principles of highest diversity and least moves?
Posts: 4021 | From: Bay Area, CA | Registered: Mar 2007
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By the way, despite the gaps in data which should be filled in due time, R-V88 is still African in origin.
Posts: 26249 | From: Atlanta, Georgia, USA | Registered: Feb 2005
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posted
Isn't R-M343 (R1b) considered African in origin? Because while reading the following:
quote:We have sought to identify signals of assimilation of African male lines in Lebanon by exploring the association of sickle cell disease (SCD) in Lebanon with Y-chromosome haplogroups that are informative of the disease origin and its exclusivity to the Muslim community. A total of 732 samples were analyzed, including 33 SCD patients from Lebanon genotyped for 28 binary markers and 19 short tandem repeats on the non-recombinant segment of the Y chromosome. Genetic organization was identified using populations known to have influenced the genetic structure of the Lebanese population, in addition to African populations with high incidence of SCD. Y-chromosome haplogroup R-M343 sub-lineages distinguish between sub-Saharan African and Lebanese Y chromosomes. We detected a limited penetration of SCD into Lebanese R-M343 carriers, restricted to Lebanese Muslims. We suggest that this penetration brought the sickle cell gene along with the African R-M343, probably with the Saharan caravan slave trade.
Source: Y-chromosome R-M343 African lineages and sickle cell disease reveal structured assimilation in Lebanon
Marc Haber1, Daniel E Platt2, Simon Khoury1, Danielle A Badro1, Miguel Abboud3, Chris Tyler-Smith4 and Pierre A Zalloua1,5 (2011)Posts: 1502 | From: Dies Irae | Registered: Oct 2010
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posted
Nevermind. It seemed as if they were implying an African origin. At the very least though, they associate R1b with African mediated gene flow. I find it strange how they say E-M35 is Asian... o well Posts: 1502 | From: Dies Irae | Registered: Oct 2010
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posted
Any R1b in Africa is not wholly indigenous. But if it makes you Afronuts feel any better, Chadic populations are autosomally pretty much completely African, their Y-DNA however is not.
Posts: 695 | From: وكان المصريون القدماء القوقازين | Registered: Jan 2011
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posted
^Perahu, please don't troll my thread with name-calling and present some evidence for your assertions. We are not discussing autosomal DNA, we are discussing a topic that may seemingly fly directly over your head judging by the pounding you've received recently from Explorer. Prepare to be ignored if you continue on with your childish name-calling rooted in your pathetic attempts at face-saving. That's right, I see Explorer has ruffled your feathers and now you feel compelled to prove yourself, but trust that it's a long journey you're about to embark on which involves potentially severe verbal beat downs and and a lot of ego deflation. I suggest you proceed with caution.
BTW, for someone with a thing against "Afronuts", I find it curious that you'd choose to name yourself after an ancient African chief. But anyways.
@L'
Lancaster's view is heretical. What does Blench have to do with Lancaster's irrelevant emphasis that goat pastoralism was "a way of life that spread from the Middle East, probably initially along the eastern side of the Nile, therefore [this] matches the DNA evidence very closely".
What DNA evidence? Levantines don't carry R-V88 and E-M35 can agree easily with a direct migration from the east and/or southeast (from WITHIN Africa).
Don't know about the study you cited but Cruciani et al (2010), which is being discussed by Lancaster identifies E-M35 as East African and they claim to not have found any R-M343 in Africa. What Lancaster is discussing is African R-V88.
Posts: 4021 | From: Bay Area, CA | Registered: Mar 2007
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quote: What DNA evidence? Levantines don't carry R-V88 and E-M35 can agree easily with a direct migration from the east and/or southeast (from WITHIN Africa).
The authors of the article I cited said that E-M35 was non-African. A very silly claim... but oh well.
quote: Don't know about the study you cited but Cruciani et al (2010), which is being discussed by Lancaster identifies E-M35 as East African and they claim to not have found any R-M343 in Africa. What Lancaster is discussing is African R-V88.
Yeah. BTW, did you see Cruciani's response to Lancaster?
-------------------- L Writes: Posts: 1502 | From: Dies Irae | Registered: Oct 2010
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posted
^No, but it would be great if you can post it.
Edit: Ok, I've found it. It appears that Blench made no such implication and Lancaster was simply presenting his own rather weak and tenuous associations. Probably just to fill up more page space (he's a relatively newer geneticist who doesn't have much published).
.......................................
Letter
European Journal of Human Genetics (2010) 18, 1186–1187; doi:10.1038/ejhg.2010.89; published online 23 June 2010
Reply to Lancaster
Fulvio Cruciani1, Beniamino Trombetta1, Daniele Sellitto2, Andrea Massaia1, Giovanni Destro-Bisol3, Elizabeth Watson4, Eliane Beraud Colomb5, Jean-Michel Dugoujon6, Pedro Moral7 and Rosaria Scozzari1
In January 2010, we published in this journal a report1 on the frequency distribution of the Y chromosome haplogroup R1b1a (R-V88) in Africa, where it can be found at frequencies as high as about 90%. This haplogroup (or its ancestor) most likely traces its origins back to Eurasia, but is presently found very rarely outside Africa.
In our original publication,1 we described two important patterns in the genotyping data. The first observation was that the highest frequencies of the R1b1a haplogroup were found among Afro-Asiatic-speaking populations from the Central Sahel, with Chadic mostly contributing to this pattern. We have now extended our analysis to a further 258 unrelated male subjects from northern Cameroon (Table 1). As can be seen from Table 1, the extended data fully confirm the pattern originally observed.
The second observation was regarding a genetic contiguity between the Chadic-speaking peoples from the Central Sahel and several other Afro-Asiatic-speaking groups from North Africa, including Ouarzazate Berbers from Morocco, Mozabite Berbers from Algeria, Siwa Berbers and several Semitic groups from Egypt, and, possibly, different groups from Algeria,2 Tunisia3 and Egypt,3, 4 with R1b1a frequencies ranging from 1 to 3% in Algeria to about 4% in Tunisia, to 26.9% in the Siwa. We interpreted these data by suggesting that they are more compatible with Ehret's hypothesis, which proposes that Chadic peoples arrived from the North through the Sahara (the ‘trans-Saharan’ hypothesis),5 rather than with Blench's theory, which states that Chadic-speaking pastoralists reached the Chad Basin through the Sahel from an eastern Sudanic Cushitic-Chadic motherland (the ‘inter-Saharan’ hypothesis).6
Considering the mitochondrial DNA, the populations from the Chad Basin also show some genetic peculiarities when compared with other populations living south of the Sahara. Mitochondrial DNA haplogroups L3f37 and L3e5,8 which are uncommon in the sub-Saharan area, were found to be relatively frequent in the Chad Basin region, with estimated coalescence ages similar to those we obtained for the Y chromosome R1b1a haplogroup. The lineage L3f3 can be traced back over the millennia to L3f,9 and this led the researchers who analyzed L3f3 from the Chad Basin7 to propose ancient links between this haplogroup and Chadic-speaking peoples coming from East or North East Africa. However, the presence in North Africa of the supposedly autochthonous Chad Basin haplogroup L3e58, 10 would seem to suggest another possible scenario, which is more compatible with the ‘trans-Saharan’ migration route.
In his Letter, Lancaster11 revisits our original data and provides valuable comments on our paper. Following his own previous review,12 he argues that our interpretation may have been affected by poor population coverage in relevant regions from East and North East Africa. We agree that data from those areas that are particularly important in order to discriminate between the two theories (eg, Eastern Egypt and Sudan) would be very important. As far as we are aware, there are no data for Eastern Egypt. The investigation by Hassan et al13 in Sudan fills in the map of North East Africa, at least in part, by providing Y-chromosome haplogroup data on additional relevant population samples. However, the power of these data is limited by the low level of resolution, as no R1b1 internal markers were analyzed. Furthermore, even if one assumes that all the R1b1 Y chromosomes found in Sudan harbor the V88 mutation, there are little data to support the hypothesis that these chromosomes are the product of an ancient migration from the East. The highest frequencies of R1b1 chromosomes from Sudan were observed in the Hausa, a Chadic-speaking population that has migrated from the West, and in the Copts, a population group that is known to be largely the result of recent migrations from Egypt over the past two centuries.13 By contrast, only two R1b1 chromosomes were found among the Beja in Sudan,13 confirming our previous results that Chadic-speaking populations are distinguished from Cushites, at least at the Y chromosome variation level.1
In summary, currently available genetic evidence seems to favor our previous hypothesis1 that the Y chromosome haplogroup R1b1a is a paternal genetic record of the proposed ‘trans-Saharan’ migration.5 It will be interesting to see how the proposed pattern develops as more detailed information about the phylogeographic structure of this haplogroup and a more refined method to estimate coalescence times become available.
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