Monday, November 29, 2010
The Expansion of haplogroup LOd from East to West Africa
LOd is the oldest haplogroup (1-4). This haplogroup is primarily carried by the Khoisan people (1-2,4). It is also found among Niger-Congo speakers in East Africa (4) and we find LOa in West Africa (3). In this paper we will examine and discuss the demic diffusion of LOd across the African continent into West Africa. This is important because we discuss an early expansion of carriers of LOd from East Africa to West Africa before the exit of homo sapien sapiens from Africa.
The majority of carriers of Haplogroup LOd live in East (and South Africa) and speak Khoisan . Haplogroup LOd probably originated in east Africa (5).
Haplogroup LOd is the most ancient genome. The LOd transitions include 14381,4232,6815,8113A, 8152,8251, 12121, 15466, 15930, 15941, 16243.
Haplogroup LOd is found at the root of human mtDNA. Gonder et al maintains that LOd is “the most basal branch of the gene tree”(5). The TMRCA for LOd is 106kya.
Haplogroup LOd predicts a significant period of time for anatomically modern humans (amh) living in Africa to spread across the continent. The existence of the LOd haplotype AF-24 among Senegalese supports this view. AF-24 is an ancient haplotype associated with LOd .
The TMRCA of LOd dates to 106kya. As a result, anatomically modern humans (amh) had plenty of time to spread this haplogroup to Senegal. In West Africa the presence of amh date to the Upper Palaeolithic (6). The archaeological evidence makes it clear that amh had ample opportunity to spread LOd to West Africa during this early period of demic diffusion.
The earliest evidence of human activity in West Africa is typified by the Sangoan industry (7). The amh associated with the Sangoan culture may have deposited Hg LOd in Senegal thousands of years before the exit of amh from Africa.
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 (6), Gambia River in Senegal (8-9); and Cap Vert (7). The distribution of the Sangoan culture supports the demic diffusion of LOd into the Senegambia over 100kya.
The first amh to reach Senegal belonged to the Sangoan culture which spread from East Africa to West Africa probably between 100-80kya . Gonder et al claimed that LOd is exclusive to the southern African Khoisan (SAK) population (5). The presence of the ancient AF-24 haplotype among the Senegalese (10), that is absent in other parts of Africa, suggest a long-term LOd population in the Senegambia that preserved this rare haplotype—that originated early in the history of amh.
1. Soares, Pedro; Luca Ermini, Noel Thomson, Maru Mormina, Teresa Rito, Arne Röhl, Antonio Salas, Stephen Oppenheimer, Vincent Macaulay and Martin B. Richards (04 Jun 2009). "Supplemental Data Correcting for Purifying Selection: An Improved Human Mitochondrial Molecular Clock". The American Society of Human Genetics 84 (6): 82–93. PMID 19500773 doi:10.1016/j.ajhg.2009.05.001. http://www.cell.com/AJHG/abstract/S0002-9297(09)00163-3. Retrieved 2009-08-13.
2. van Oven, Mannis; Manfred Kayser (13 Oct 2008). "Updated comprehensive phylogenetic tree of global human mitochondrial DNA variation". Human Mutation 30 (2): E386-E394. PMID 18853457 doi:10.1002/humu.20921. http://www3.interscience.wiley.com/journal/121449735/abstract?CRETRY=1&SRETRY=0. Retrieved 2009-05-20.
3. Rosa, A. et al. 2004 July. "MtDNA Profile of West Africa Guineans: Towards a Better Understanding of the Senegambia Region", "Annals of Human Genetics", 68(Pt 4): 344
4. Sarah A. Tishkoff et al. 2007, History of Click-Speaking Populations of Africa Inferred from mtDNA and Y Chromosome Genetic Variation. Molecular Biology and Evolution 2007 24(10):2180-2195
5. Gonder MK, Mortensen HM, Reed FA, de Sousa A, Tishkoff SA.(2006).: Whole mtDNA Genome Sequence Analysis of Ancient African Lineages. Mol Biol Evol., Dec 28.
6. Giresse,P. (2008). Tropical and sub-Tropical West Africa—marine and Continental changes during the late Quaternary. Volume 10. Elsevier Science.
7. Phillipson, D.W.(2005). African Archaeology. Cambrige.
8. Davies,O. (1967). West Africa before the Europeans. London.
9. Wai-Ogusu,A.(1973). Was there a Sangoan industry in West Africa, West African Jour of Arcaheo,3:191-96.
10. Chen YS, Olckers A, Schurr TG, Kogelnik AM, Huroponen K, Wallace DC. (2000). mtDNA variation in the South African Kung and Khwe—and Their genetic relationships to other African populations. Am J Hum Genet, 66(4): 1362-1383.
Posted by Dr. Clyde Winters at 10:07 AM
Subscribe to: Post Comments (Atom)
Post a Comment