Regarding time depth, essentially all studies of mtDNA variation in Europe have drawn conclusions regarding demographic phenomena occurring in a rather remote past. Neolithic or even Paleolithic demographic processes have been inferred from patterns in modern mtDNA diversity in the absence of genetic information on past populations (see, e.g., refs. 10 and 27–29) under the implicit assumption of genetic continuity among people dwelling in the same region at different time periods. The results of this study imply that this assumption is not always correct and that theProc. Natl. Acad. Sci. USA, 10.1073/pnas.0509718103
mitochondrial gene pool can undergo a drastic turnover in as few as 100 generations.
Serial coalescent simulations suggest a weak genealogical relationship between Etruscans and modern Tuscans
Elise M. S. Belle et al.
The Etruscans, the only preclassical European population that has been genetically characterized so far, share only two haplotypes with their modern geographic counterparts, the Tuscans, who, nonetheless, appear to be their closest relatives. We modeled 10 demographic scenarios spanning the last 2,500 years and tested by serial coalescent simulation whether any are consistent with the patterns of genetic diversity observed within and between the Etruscan and the modern Tuscan populations. Models in which the Etruscans are the direct ancestors of modern Tuscans appear compatible with the observed data only when they also include a very high mutation rate and an ancient founder effect. A better fit was obtained when the ancient and the modern samples were extracted from two independently evolving populations, connected by little migration. Simulated and observed parameters were also similar for a scenario in which the ancient samples came from a subset, e.g., a social elite, genetically differentiated from the bulk of the Etruscan population. In principle, these results may be biased by factors such as gross and systematic errors in the ancient DNA sequences and failure to sample suitable modern individuals. If neither proves to be the case, this study strongly suggests that either the mitochondrial mutation rate is much higher than currently believed or the Etruscans left very few modern mitochondrial descendants.