Tuesday, November 30, 2010
Haplotype AF-24: An Ancient African Gene
An important haplotype in Africa is Af-24. AF-24 is delineated by a DdeI site at 10394 and AluI site of np 10397. This haplotype is a branch of the African subhaplogroup LOd. The TMRCA for LOd is 106kya (Gonder et al, 2006). This makes haplotype AF-24 much older than L3a.
The basal L3 motif is characterized by the Ddel site np 10394 and Alul site np 10397. The DdeI site np 10394 and AluI site np 10397 in haplotype AF24 (DQ112852) are at the base of the M macrohaplogroup.
The mtDNA LOd is mainly found in West Africa and among the Khoisan of South Africa and Tanzania.
Since the TMRCA of LOd dates to 106kya Anatomically modern humans (amh) had plenty of time to take this haplogroup to Senegal. In West Africa the presence of amh date to the Upper Palaeolithic (Giresse,2008).
Anatomically modern humans arrived in Senegal during the Sangoan period. Sangoan artifacts spread from East Africa to West Africa between 100-80kya. In Senegal Sangoan material has been found near Cap Manuel, Gambia(Giresse, 2008).
In conclusion, the earliest evidence of human activity in West Africa is typified by the Sangoan industry (Phillipson,2005). The amh associated with the Sangoan culture may have deposited Hg LOd and haplotype AF-24 in Senegal thousands of years before the exit of amh from Africa.
Giresse,P. (2008). Tropical and sub-Tropical West Africa—marine and Continental changes during the late Quaternary. Volume 10. Elsevier Science.
Gonder MK, Mortensen HM, Reed FA, de Sousa A, Tishkoff SA: Whole mtDNA Genome Sequence Analysis of Ancient African Lineages. Mol Biol Evol. 2006, Dec 28.
Phillipson, D.W.(2005). African Archaeology. Cambrige.