January 07, 2013

mtDNA variation in East Africa (Boattini et al. 2013)

From the paper:
Language diversity in EA fits well with its complicated genetic history. In Fleming words, ‘‘Ethiopia by itself has more languages than all of Europe, even counting all the so-called dialects of the Romance family’’ (Fleming, 2006). All African linguistic phyla are found in EA: Afro-Asiatic (AA), Nilo-Saharan, Niger-Congo and Khoisan (however, the genealogical unit of Khoisan is no longer generally accepted). Among them, AA is the most differentiated, being represented by three (Omotic, Cushitic, Semitic) of its six major clades (the others being Chadic, Berber and Egyptian). Omotic and Cushitic are considered the deepest clades of AA, and both are found almost exclusively in the Horn of Africa, along with the linguistic relict Ongota that is traditionally assigned to the Cushitic family but whose classification is still widely debated (Fleming, 2006). These observations are in agreement with a North-Eastern African origin of the AA languages, most probably in pre-Neolithic times (Ehret, 1979, 1995; Kitchen et al., 2009).
and:

This study confirms the central role of EA and the Horn of Africa in the genetic and linguistic history of a wide area spanning from Central and Northern Africa to the Levant. Our results confirm high mtDNA diversity and strong genetic structuring in EA. We were indeed able to identify three population clusters (A, B1, B2) that are related both to geography and linguistics, and signaling different population events in the history of the region. The Horn of Africa (cluster A), in accordance with its role as a major gateway between sub-Saharan Africa and the Levant, shows widespread contacts with populations from CA (AA-Chadic speakers), the Arabian peninsula and the Nile Valley. Southwards, Kenya, and Tanzania (clusters B1 and B2), despite being both heavily involved in Bantu and Nilo-Saharan pastoralist expansions, reveal traces of a more ancient genetic stratum associated with Cushitic-speaking groups (cluster B2). Conversely, Berber- and Semitic-speaking populations of NA and the Levant show only marginal traces of admixture with sub-Saharan groups, as well as a different mtDNA genetic background, making the hypothesis of a Levantine origin of AA unlikely. In conclusion, EA genetic structure configures itself as a complicated palimpsest in which more ancient strata (AA-Cushiticspeaking groups) are largely overridden by recent different migration events. Further explorations of AA-Cushitic- speaking populations – both in terms of sampled groups and typed genetic markers – will be of great importance for the reconstruction of the genetic history of EA and AA-speakers. 

The African origin of Afroasiatic would agree with its linguistic separateness from Eurasian languages, and the fact that a single branch of the family (Semitic) is likely to have originated in Asia, and fairly recently at that.

Related:



Am J Phys Anthropol DOI: 10.1002/ajpa.22212

mtDNA variation in East Africa unravels the history of afro-asiatic groups

Alessio Boattini et al.

East Africa (EA) has witnessed pivotal steps in the history of human evolution. Due to its high environmental and cultural variability, and to the long-term human presence there, the genetic structure of modern EA populations is one of the most complicated puzzles in human diversity worldwide. Similarly, the widespread Afro-Asiatic (AA) linguistic phylum reaches its highest levels of internal differentiation in EA. To disentangle this complex ethno-linguistic pattern, we studied mtDNA variability in 1,671 individuals (452 of which were newly typed) from 30 EA populations and compared our data with those from 40 populations (2970 individuals) from Central and Northern Africa and the Levant, affiliated to the AA phylum. The genetic structure of the studied populations—explored using spatial Principal Component Analysis and Model-based clustering—turned out to be composed of four clusters, each with different geographic distribution and/or linguistic affiliation, and signaling different population events in the history of the region. One cluster is widespread in Ethiopia, where it is associated with different AA-speaking populations, and shows shared ancestry with Semitic-speaking groups from Yemen and Egypt and AA-Chadic-speaking groups from Central Africa. Two clusters included populations from Southern Ethiopia, Kenya and Tanzania. Despite high and recent gene-flow (Bantu, Nilo-Saharan pastoralists), one of them is associated with a more ancient AA-Cushitic stratum. Most North-African and Levantine populations (AA-Berber, AA-Semitic) were grouped in a fourth and more differentiated cluster. We therefore conclude that EA genetic variability, although heavily influenced by migration processes, conserves traces of more ancient strata.

Link

3 comments:

Ponto said...

The age estimates of language families are irrelevant. Most main spoken languages existing today are the result of a post Neolithic population explosion brought about by the cultural adaptation of farming and forms of animal husbandry. It does not matter if the language is a Semitic derivative, Arabic, Amharic or Hebrew, or the I.E derivatives like English, Spanish or Russian. Since humans have the capacity to speak and form coherent sentences, languages are equally as ancient.

The Afro-Asiatic group of languages is mostly an imaginative creation. Linking languages on the basis of a few characteristics apparently shared or most likely coincidental, is not a good way to find out how languages are truly related. Berber languages, ancient Egyptian, Semitic languages, Chadic and those others placed into that group have low or no mutual intelligibility. Even most people able to speak classical Arabic would not even understand Hebrew and those two languages are of the same family derived from Shem of Bible fame.

Linguistics as a serious study is a sad joke especially when the efforts to produce Proto languages are actually heard and seem as in the Prometheus film, or the mumbo jumbo used for Egyptian in the Mummy films. Quite laughable.

Ezr said...

Ponto,

" "a few characteristics apparently shared or most likely coincidental" -

I'm sorry, but THAT sounds like nonsensical 'mumbo-jumbo'. Either those characteristics are shared or they are not. If they are shared, there should be evidence in the form of regular changes that can be traced back to a common source - it is the job of the historical linguist to pinpoint those rules. If they are coincidental, there will not be any such evidence.

If the evidence is slow in coming, it's back to the drawing board - as it has been for much of the history of the AA proposal, or other hypothetical families for that matter. I agree with you on this case, because AFAIK and IMHO I don't think AA is a wholly settled case. But for different reasons.

The comparative method is key. Hand-waving at what seems "likely" or "unlikely" to you is not.

And "intelligibility" doesn't matter at all. And why would it? Languages can change very fast, and, this is important, not just in a "vertical" way. The real issue is regularity in sound changes, particularly morphophonology.

On your last comment, I'm not sure what Hollywood has to do with the efforts of linguists or how you can judge one on the basis of the other. Talk about shallow judgment... Are Physics and Biology "a joke" because of bad sci-fi movies, too?

eurologist said...

Even most people able to speak classical Arabic would not even understand Hebrew

Ponto,

That doesn't matter at all and is truly not an objective measure - most people are not trained at adapting to slight sound and grammatical shifts. Conversely, a person who knows several languages and many dialects may very well be able to adapt in a very short time.

I learned Latin and can read Spanish reasonably well, and get the gist out of most French and Italian writings, and can even understand a portion of it. I am fluent in English and German and can understand and "read" Low German - which makes it possible for me to also read Dutch quite well - even though I have a hard time understanding it.

The more cosmopolitan people are on a short and medium scale, the easier it becomes to understand languages in the same family. Just because French and Russian are completely unintelligible does not mean that they are not extremely closely related.