Evolution of the human Y chromosome helps us understand the Great Human Diaspora

Studies of Y chromosomes over the past several decades have opened a window into the history of the Homo sapiens sapiens species, through the reconstruction and exploitation of a patri-lineal (Y-genealogical) tree, based on hundreds of variants. It is now very clear that modern human originated in southeast Africa and migrated (in an as-yet-undetermined number of waves) out of Africa. Geographically-isolated groups that remain (virtually 100% inbreeding) for ~10,000 years or longer have resulted in the five unique continental super-populations: African, East Asian, Oceanian, Caucasian, and Amerindian. From these five have come all later ethnic groups––by way of the Great Human Diaspora. The attached report validates, refines, and extends this tree by incorporating >65,000 Y-linked SNVs identified in 1,244 males representing worldwide diversity.

Among the sequences of 1,244 human Y chromosomes randomly ascertained from 26 worldwide populations by the 1000 Genomes Project, authors [attached] identified more than 65,000 variants––including single-nucleotide variants (SNVs), multiple-nucleotide variants, insertions and deletions (indels), short tandem repeats, and copy number variants (CNVs). Of these, CNVs contributed the greatest predicted functional impact.

Authors constructed a calibrated phylogenetic tree on the basis of binary SNVs and projected the more complex variants onto it, estimating the number of mutations for each class. Their phylogeny shows bursts of extreme expansion in male numbers that have occurred independently among each of the five continental superpopulations examined, which coincide amazingly well with the times of known migrations and technological innovations !

Nat Genet   June 2o16;  48: 593-599 (article)  and  pp 588-589 (ed.)


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