Ethiopian Genetic Diversity Reveals Linguistic Stratification and Complex Influences on the Ethiopian Gene Pool

Division of Biological Anthropology, University of Cambridge, UK.
The American Journal of Human Genetics (Impact Factor: 10.93). 06/2012; 91(1):83-96. DOI: 10.1016/j.ajhg.2012.05.015
Source: PubMed


Humans and their ancestors have traversed the Ethiopian landscape for millions of years, and present-day Ethiopians show great cultural, linguistic, and historical diversity, which makes them essential for understanding African variability and human origins. We genotyped 235 individuals from ten Ethiopian and two neighboring (South Sudanese and Somali) populations on an Illumina Omni 1M chip. Genotypes were compared with published data from several African and non-African populations. Principal-component and STRUCTURE-like analyses confirmed substantial genetic diversity both within and between populations, and revealed a match between genetic data and linguistic affiliation. Using comparisons with African and non-African reference samples in 40-SNP genomic windows, we identified "African" and "non-African" haplotypic components for each Ethiopian individual. The non-African component, which includes the SLC24A5 allele associated with light skin pigmentation in Europeans, may represent gene flow into Africa, which we estimate to have occurred ~3 thousand years ago (kya). The non-African component was found to be more similar to populations inhabiting the Levant rather than the Arabian Peninsula, but the principal route for the expansion out of Africa ~60 kya remains unresolved. Linkage-disequilibrium decay with genomic distance was less rapid in both the whole genome and the African component than in southern African samples, suggesting a less ancient history for Ethiopian populations.

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    • " in Uganda has a likely European source , for example , resulting from the heavy European colonial involvement since the 1870s ( Maxon 2009 ) . One possibility is a Bronze - Age dispersal from the Near East accompanying the spread of Semitic languages ( Kitchen et al . 2009 ) , consistent with an inferred Levantine ( rather than Arabian ) source ( Pagani et al . 2012 ) . However , the T1a lineage is a possible candidate , and it is also possible that the Arabian lineages in Uganda , such as HV1b1 , might only have arrived very recently in the Great Lakes region . We therefore used 46 autosomal AIMs to explore further the ancestry of the individuals carrying HV1b1 and T1a , to test whether or not the"
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