Barbujani and Chikhi on genetic contribution of Neolithic

The recent study of Neolithic mtDNA from Central European proto-farmers was interpreted by the authors of the study as evidence for limited contribution of the Neolithic in the modern European gene pool. From the cited commentary:

As noted above, a major part of the controversy has revolved around the age of haplogroups. Since these ages were used by Richards and collaborators to identify 'palaeolithic' and 'neolithic' components of the modern gene pool, one would expect Neolithic specimens to only yield 'neolithic', haplogroup J, sequences. The population genetics prediction, however, is that 'Neolithic' people should have both types of haplogroups. Interestingly, Haak et al (2005) found only one sequence belonging to haplogroup J, with six sequences belonging to the currently very rare N1a haplogroup, and 17 to haplogroups that were termed 'Paleolithic' (Richards et al, 2000), such as H, V and K. Surprisingly, this information was not used by the authors, even though it demonstrates that ages of molecules cannot be equated with ages of populations, a point made some time ago by supporters of the demic diffusion model (Barbujani et al, 1998). Population genetics theory teaches us that migrating people carry alleles and haplogroups in their genome originating from mutations that occurred before, sometimes long before, the migratory movement started, and inferring from the former the date of the latter is never straightforward. It might be legitimate (although, we think, misleading) to term haplotypes derived from mutations <10 000 years old as 'Neolithic', but the frequency of those haplotypes has little to do with the Neolithic contribution to the European gene pool.

Heredity advance online publication 24 May 2006; doi: 10.1038/sj.hdy.6800852

Population genetics: DNAs from the European Neolithic

G Barbujani and L Chikhi

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