Diversity project takes time but reaps rewards.
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Biomedical subjects
Publications and source records attributed to Luigi Luca Cavalli-Sforza.
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Allelic frequencies of 182 tri- and tetra-autosomal microsatellites were used to examine phylogenetic relationships among 19 extant human populations. In particular, because the languages of the Basques and Hunza Burusho have been suggested to have an ancient relationship, this study sought to explore the genetic relationship between these two major language isolate populations and to compare them with other human populations. The work presented here shows that the microsatellite allelic diversity and the number of unique alleles were highest in sub-Saharan Africans. Neighbor-joining trees based on genetic distances and principal component analyses separated populations from different continents, and are consistent with an African origin for modern humans. For the first time, with biparentally transmitted markers, the microsatellite tree also shows that the San are the first branch of the human tree before the branch leading to all other Africans. In contrast to an earlier study, these results provided no evidence of a genetic relationship among the two language isolate groups. Genetic relationships, as ascertained by these microsatellites, are dictated primarily by geographic proximity rather than by remote linguistic origin, Mantel test, R(0) = 0.484, g = 3.802 (critical g value = 1.645; P = 0.05).
The genetic composition of the Norwegian population was investigated by analysing polymorphisms associated with both the mitochondrial DNA (mtDNA) and Y chromosome loci in a sample of 74 Norwegian males. The combination of their uniparental mode of inheritance and the absence of recombination make these haplotypic stretches of DNA the tools of choice in evaluating the different components of a population's gene pool. The sequencing of the Dloop and two diagnostic RFLPs (AluI 7025 and HinfI at 12 308) allowed us to classify the mtDNA molecules in 10 previously described groups. As for the Y chromosome the combination of binary markers and microsatellites allowed us to compare our results to those obtained elsewhere in Europe. Both mtDNA and Y chromosome polymorphisms showed a noticeable genetic affinity between Norwegians and central Europeans, especially Germans. When the phylogeographic analysis of the Y chromosome haplotypes was attempted some interesting clues on the peopling of Norway emerged. Although Y chromosome binary and microsatellite data indicate that 80% of the haplotypes are closely related to Central and western Europeans, the remainder share a unique binary marker (M17) common in eastern Europeans with informative microsatellite haplotypes suggesting a different demographic history. Other minor genetic influences on the Norwegian population from Uralic speakers and Mediterranean populations were also highlighted.