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Figure 9 shows clusters I, W and X, charac-terised by the ancestral state at position 16223(which was probably the major ‘out-of-Africa’sequence: Calafell et al. 1996; Watson et al. 1997).Together, these clusters comprise only 5% of the total data set. Cluster I may be fairly ancient:C 35000 years old in Europe (cf. 26000–34 000years: Torroni et al. 1994), although this age strongly depends on the time of appearance ofthe mutation at 16311 on the 16129–16223 background. Cluster I is now very rare, occurring at only C 2% in the present data set, and seemingly distributed mainly in the north and west of Europe. Cluster W has a more recent age of 18500 years (although W may, as with T,break down into several founder clusters of more recent age) and appears more diverse in southern than northern Europe, but this may again simply reflect its rarity – only 1% of the present data. The 16189–16223–16278 signature charac-teristic of most of cluster X seems to have been at the centre of an expansion, forming a simplestar-like phylogeny, with an age of C 24000 years (although the low frequency of theselineages, at again only C 2%, again render anyconclusion extremely tentative). Surprisingly,cluster X also occurs at low frequency amongst native North Americans (Ward et al. 1991;Bandelt et al. 1995; Scozzari et al. 1997). Thismay suggest a common origin with Europeancluster X in the vicinity of the Near East.
