Wednesday, 30 March 2011

Fertile Crescent impact in Africa (plus East African looses quotation marks)

As a method to estimate Fertile Crescent admixture in SubSaharan Africa, as well as uncover any recent affinities between West African and East African populations, I set up a run including all populations Africa I have available right now, plus some Middle Eastern ones.
As poles I designed FC + all current forager populations available:
1. Mbuti Pygmies (from the Congo region)
2. Biaka Pygmyes (from the Congo region)
3. !Kung (from Southwest Africa)
4. San (from far Southwest Africa)
5. Hadza (from Tanzania)
6. Turks+Druze

As for the other populations analysed. Bantu=Niger-Congo B
Maasai (Kenya/Tanzania, Nilo-Saharan speaking); Bantu Kenya; Luhya (Kenya, Bantu speaking); Alur (Uganda/East Congo, Nilo-Saharan); Hema (Uganda/East Congo, Nilo-Saharan or Bantu);
Fulani (West Africa, very dispersed group, Niger-Congo speaking); Bambaran (Mali, language of probable Niger-Congo A family); Bulala (Chad, Nilo-Saharan); Kaba (Chad/CAR, Nilo-Saharan); Dogon (Mali, Niger-Congo); Mandenka (West Africa, Niger-Congo); Brong (Ghana, Niger-Congo); Hausa (West Africa, Afro-Asiatic); Yoruba (West Africa, Niger-Congo); Igbo (West Africa), Niger-Congo); Mada (West Africa, Niger-Congo)
Bamoun (Cameroon, Niger-Congo); Fang (Cameroon/Congo, Bantu); Kongo (Congo/Angola, Bantu); Nguni (South Africa, Bantu); Pedi (South Africa, Bantu); Sotho/Tswana (South Africa, Bantu); Xhosa (South Africa, Bantu); BantuSouthAfrica

Please bear in mind, the results don't necessarily imply close affinity of any agricultural population with any particular group, Forager ancestors of current agriculturalists obviously don't exist as foragers anymore and likely were substantially different from current ones. This is just an experiment to check if unsupervised ADMIXTURE was hiding anything (i.e. old stabilized admixture events) behind East and West African modal components.

Even though Foragers likely have some admixture with agriculturalists, East African appears to be a distinct component. Yoruba have no visible Fertile crescent contribution, I will use them as well as a pole in the future again.

This was a highly experimental run, not sure if detailed interpretations should be made. Still I think ADMIXTURE is lumping together groups as well as it can, even if it has to put pole populations at extreme positions within the component based on them. So the !kung component is I believe more West African here, possibly stretched to include them themselves. The relationships are still valid though. And so is the conclsion, that as long as Hadza have no significant real Fertile Crescent admixture (as seems likely), there is little Fertile Crescent genetic influence in Subsaharan Africa except for Ethiopians, Maasai and Fulani.

1 comment:

  1. This is a great concept! Foragers were there before farming populations so why not analyze farming populations as mixtures of foraging ones? I predict that as more foraging populations from all parts of the world are included in the analysis, the insights into the origins of neolithic populations will get even deeper.