Monday 14 May 2007
Genetic studies of the Arabian Peninsula are scarce even though the region was the center of ancient trade routes and empires and may have been the southern corridor for the earliest human migration from Africa to Asia.
The Saudi Arabian group showed greatest similarity to other Arabian Peninsula populations (Bedouin from the Negev desert and Yemeni) and to Levantine populations.
Nearly all the main western Asia haplogroups were detected in the Saudi sample, including the rare haplogroup U9.
Saudi Arabs had only a minority sub-Saharan Africa component (7%), similar to the specific North-African contribution (5%). In addition, a small Indian influence (3%) was also detected.
The majority of the Saudi-Arab mitochondrial DNA lineages (85%) have a western Asia provenance. Although the still large confidence intervals, the coalescence and phylogeography of (preHV)1 haplogroup (accounting for 18 % of Saudi Arabian lineages) matches a Neolithic expansion in Saudi Arabia.
The "southern coastal route" model
A major unanswered question regarding the dispersal of modern humans around the world concerns the geographical site of the first human steps outside of Africa.
The "southern coastal route" model predicts that the early stages of the dispersal took place when people crossed the Red Sea to southern Arabia, but genetic evidence has hitherto been tenuous.
Analyzing the three minor west-Eurasian haplogroups, N1, N2, and X.
These lineages branch directly from the first non-African founder node, the root of haplogroup N, and coalesce to the time of the first successful movement of modern humans out of Africa, ∼60 thousand years (ka) ago.
The sequencing of mtDNA genomes from 85 Southwest Asian samples carrying these haplogroups and their comparison with a database of 300 European examples show that these minor haplogroups have a relict distribution that suggests an ancient ancestry within the Arabian Peninsula, and they most likely spread from the Gulf Oasis region toward the Near East and Europe during the pluvial period 55-24 ka ago.
This pattern suggests that Arabia was indeed the first staging post in the spread of modern humans around the world.
The Arabian Cradle: Mitochondrial Relicts of the First Steps along the Southern Route out of Africa. Fernandes V, Alshamali F, Alves M, Costa MD, Pereira JB, Silva NM, Cherni L, Harich N, Cerny V, Soares P, Richards MB, Pereira L. Am J Hum Genet. 2012 Jan 24. PMID: 22284828
Abu-Amero KK, Gonzalez AM, Larruga JM, Bosley TM, Cabrera VM. Eurasian and African mitochondrial DNA influences in the Saudi Arabian population. BMC Evol Biol. 2007 Mar 1;7:32. PMID: 17331239