Barbara Arredi

A predominantly neolithic origin for Y-chromosomal DNA variation in North Africa.

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.

Anthropological Genetics: The Peopling of Europe

SUMMARY Although hominins were present in Europe as early as ~780 thousand years ago, there is broad agreement that these archaic humans, including Neanderthals, contributed little to the contemporary European gene pool. In contrast, there is vigorous debate about the relative contributions of humans who entered in the Upper Paleolithic and Neolithic. Here, we argue that the Y-chromosomal diversity pattern is likely to have a largely Neolithic or later origin. In addition to the genome-wide influences resulting from migration, admixture and drift, the effects of positive selection are detectable around some genes, such as lactase. Studies of species associated with humans, e.g. cattle, are providing additional insights.

Y chromosome genetic structure in the Italian peninsula

We investigated Y chromosome populations structure in the Italian peninsula by means of a number of microsatellites and SNPs markers. Genetic analysis revealed a certain degree of heterogeneity between samples at both haplotype (hpt) and haplogroup (hg) level. Implications in genetic history and forensic are discussed. D 2003 Published by Elsevier B.V.