title: A predominantly neolithic origin for Y-chromosomal DNA variation in North Africa.
abstract: We have typed 275 men from five populations in Algeria, Tunisia, and Egypt with a set of 119 binary markers and 15 microsatellites from the Y chromosome, and we have analyzed the results together with published data from Moroccan populations. North African Y-chromosomal diversity is geographically structured and fits the pattern expected under an isolation-by-distance model. Autocorrelation analyses reveal an east-west cline of genetic variation that extends into the Middle East and is compatible with a hypothesis of demic expansion. This expansion must have involved relatively small numbers of Y chromosomes to account for the reduction in gene diversity towards the West that accompanied the frequency increase of Y haplogroup E3b2, but gene flow must have been maintained to explain the observed pattern of isolation-by-distance. Since the estimates of the times to the most recent common ancestor (TMRCAs) of the most common haplogroups are quite recent, we suggest that the North African pattern of Y-chromosomal variation is largely of Neolithic origin. Thus, we propose that the Neolithic transition in this part of the world was accompanied by demic diffusion of Afro-Asiatic-speaking pastoralists from the Middle East.
authors.affiliation: Istituto di Medicina Legale, Università Cattolica del Sacro Cuore di Roma, Rome, Italy. b_arredi@libero.it
authors.forename: Barbara
authors.initials: B
authors.lastname: Arredi
authors.forename: Estella S
authors.initials: ES
authors.lastname: Poloni
authors.forename: Silvia
authors.initials: S
authors.lastname: Paracchini
authors.forename: Tatiana
authors.initials: T
authors.lastname: Zerjal
authors.forename: Dahmani M
authors.initials: DM
authors.lastname: Fathallah
authors.forename: Mohamed
authors.initials: M
authors.lastname: Makrelouf
authors.forename: Vincenzo L
authors.initials: VL
authors.lastname: Pascali
authors.forename: Andrea
authors.initials: A
authors.lastname: Novelletto
authors.forename: Chris
authors.initials: C
authors.lastname: Tyler-Smith
mesh_terms: D000352:Africa, Northern; D041322:Chromosomes, Human, Y; D019143:Evolution, Molecular; D014644:Genetic Variation; D006801:Humans; D008297:Male; D010802:Phylogeny