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H.C. Harpending and E. Eller
Fig. 3. The ten world language macro-families described in Ruhlen (1994)
2M
F = 1 - -
(1)
.,
sG
while neutral traits would follow migration-drift equilibrium for which
1
F., = 2M +1
(2)
These are abstract but we can obtain a feel for magnitudes involved by using some
human data and plausible population parameters. FSI among continental groups is
about ten percent, implying from equation (2) that M - 4.5 corresponding to 2
diploid migrants per generation. Relethford (Relethford 1994) estimates FSI for human skin color to be about 0.6, that is six times as great as that of neutral genes. If
the effective size of our human islands is G =10000, equation (1) implies s - O.OOL
This is a very low intensity of selection, a level that is probably undetectable by
epidemiological methods.
3.3 World Languages
Language ought in some cases to follow something like our model of common type
advantage, as we proposed for Basque. Figure 3 is a map (redrawn from Ruhlen
1994) of world languages lumped into the largest possible groups by Ruhlen. This