A back migration from Asia to sub-Saharan Africa is supported by high-resolution analysis of human Y-chromosome haplotypes.
The variation of 77 biallelic sites located in the nonrecombining portion of the Y chromosome was examined in 608 male subjects from 22 African populations. This survey revealed a total of 37 binary haplotypes, which were combined with microsatellite polymorphism data to evaluate internal diversities and to estimate coalescence ages of the binary haplotypes. The majority of binary haplotypes showed a nonuniform distribution across the continent. Analysis of molecular variance detected a high level of interpopulation diversity (PhiST=0.342), which appears to be partially related to the geography (PhiCT=0.230). In sub-Saharan Africa, the recent spread of a set of haplotypes partially erased pre-existing diversity, but a high level of population (PhiST=0.332) and geographic (PhiCT=0.179) structuring persists. Correspondence analysis shows that three main clusters of populations can be identified: northern, eastern, and sub-Saharan Africans. Among the latter, the Khoisan, the Pygmies, and the northern Cameroonians are clearly distinct from a tight cluster formed by the Niger-Congo-speaking populations from western, central western, and southern Africa. Phylogeographic analyses suggest that a large component of the present Khoisan gene pool is eastern African in origin and that Asia was the source of a back migration to sub-Saharan Africa. Haplogroup IX Y chromosomes appear to have been involved in such a migration, the traces of which can now be observed mostly in northern Cameroon.
Cruciani
Fulvio
F
Dipartimenti di Genetica e Biologia Molecolare, Università La Sapienza, Rome, Italy. fulvio.cruciani@uniroma1.it
Santolamazza
Piero
P
Shen
Peidong
P
Macaulay
Vincent
V
Moral
Pedro
P
Olckers
Antonel
A
Modiano
David
D
Holmes
Susan
S
Destro-Bisol
Giovanni
G
Coia
Valentina
V
Wallace
Douglas C
DC
Oefner
Peter J
PJ
Torroni
Antonio
A
Cavalli-Sforza
L Luca
LL
Scozzari
Rosaria
R
Underhill
Peter A
PA
D000349:Africa; D017954:Africa South of the Sahara; D000483:Alleles; D001208:Asia; D044466:Asian People / Q000235:genetics; D044383:Black People / Q000235:genetics*; D004641:Emigration and Immigration; D005787:Gene Frequency; D005788:Gene Pool; D014644:Genetic Variation / Q000235:genetics; D006239:Haplotypes / Q000235:genetics*; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D010802:Phylogeny; D011110:Polymorphism, Genetic / Q000235:genetics; D014998:Y Chromosome / Q000235:genetics*