Lactase persistence variants in Arabia and in the African Arabs.
Lactase persistence (LP), the state enabling the digestion of milk sugar in adulthood, occurs only in some human populations. The convergent and independent origin of this physiological ability in Europe and Africa is linked with animal domestication that either had started in both places independently or had spread from the Near East by acculturation. However, it has recently been shown that at least in its southern parts, the population of Arabia not only has a different LP-associated mutation profile than the rest of Africa and Europe but also had experienced an independent demographic expansion occurring before the Neolithic around the Pleistocene-Holocene boundary. In Arabia, LP is associated with mutation -13,915*G and not, as in Europe, with -13,910*T or, as in Africa, with -13,907*G and -14,010*C. We show here that, in Arabia, -13,915*G frequency conforms to a partial clinal pattern and that this specific mutation has likely been spread from Arabia to Africa only recently from the sixth century AD onward by nomadic Arabs (Bedouins) looking for new pastures. Arabic populations in Africa that still maintain a nomadic way of life also have more -13,915*G variants and fewer sub-Saharan L-type mitochondrial DNA haplogroups; this observation matches archaeological and historical records suggesting that the migration of Arabic pastoralists was accompanied by gradual sedentarization that allowed for admixture with the local African population.
Department of Anthropology and Human Genetics, Faculty of Science, Charles University, Prague, Czech Republic.
Edita
E
Priehodová
National Corporation for Antiquities and Museums, Khartoum, Sudan.
Abdelhay
A
Abdelsawy
National Museum of Natural History, Paris, France.
Evelyne
E
Heyer
Institute of Archaeology, Academy of Science, Prague, Czech Republic.
Viktor
V
Cerný
D000069:Acculturation; D000328:Adult; D000349:Africa / Q000208:ethnology; D000818:Animals; D018912:Arabs / Q000235:genetics*; D044383:Black People / Q000235:genetics*; D004272:DNA, Mitochondrial; D019143:Evolution, Molecular; D014644:Genetic Variation / Q000235:genetics*; D006239:Haplotypes / Q000235:genetics; D049691:History, Medieval; D006801:Humans; D043322:Lactase / Q000235:genetics*; D007785:Lactose / Q000378:metabolism*; D008877:Middle East; D009154:Mutation / Q000235:genetics; D014171:Transients and Migrants; D015006:Yemen / Q000208:ethnology
D004272:DNA, Mitochondrial; D043322:Lactase; D007785:Lactose