Reconstruction of ancient genetic isolates through surnames.

Surnames are analogous to Y-chromosome genes in patrilineal transmission, but they are cultural characters derived from words of local dialects. This double aspect allows us to study the geographic distribution of surnames and to analyse their linguistic derivation in order to reconstruct recent or ancient migrations and find out the ancient isolates where individuals (and their genes) originated: thus, groups of individuals being genetically homogeneous due to their common geographic origin can be identified. We applied this approach to a sample of 257 Sardinian males analysed for the Y-chromosome specific genetic system 49a,f/Taq I RFLPs and ascribed, through the analysis of surnames, to three geographical areas of Sardinia which we considered historically and culturally distinct. We identified 27 haplotypes, 5 of which show a frequency higher than 5%. Haplotypes 5, 7, 8 and 15 are uniformly distributed in the three areas, while haplotype 12, which is today present in all parts of the island, when redistributed according to the surname origin of its carriers, shows a significantly high frequency in the mountainous central-eastern zone of the island, inhabited by the ancient Sardinian population, which lived a long history of isolation. We hypothesize that haplotype 12 originated in this area, increased its frequency by drift and, later, dispersed by migration.