An analysis of the ABO blood group clines in Europe.

With estimates of the fitnesses of the genotypes and selection by incompatibility for the ABO locus which seem reasonable given the state of knowledge, a computer model has been developed to replicate the clines of the A and B genes in Europe. With a fitness change in the BB and BO genotypes of as little as 0.5%, the differences in the frequencies in East and West Europe can be maintained at equilibrium. Appreciable changes in the amount of migration does not affect the equilibrium frequencies in the two areas significantly, while with no selection through incompatibility the equilibrium frequencies were changed about 5%. For many years the east-west cline in the frequency of the blood group B gene in Europe has been known. The increase in the B gene frequency in Eastern Europe has generally been attributed to an Asiatic origin (Haldane, '40), while Candela ('42) was more specific in attributing it to the incursions of Mongoloid peoples into Europe from the fifth to the fifteenth centuries A. D. Recently, this explanation has been increasingly questioned (e.g., Coon, '65), and this doubt has been due primarily to the gradual recognition of the importance of natural selection as a force maintaining the frequencies of the ABO blood group genes. Brues ('54) showed that the world frequencies were clustered in one small area of the distribution, which implied that some force was maintaining them in this restricted range, and the great amount of work showing the presence of maternal-fetal incompatibiIity and of differential susceptibility to disease at the ABO locus have implicated selection as this force. However, so many of the investigations are contradictory that it is difficult to draw explicit conclusions from them (for reviews of the various aspects of the ABO blood groups, see Reed, '67; Hiraizumi, '64; Otten, '67; Cohen and Sayre, '68). The purpose of this paper is to attempt to replicate the clines for the ABO blood group genes in Europe by assigning fitnesses to the genotypes which seem reasonable estimates given the nature of our knowledge of the ARO blood groups AM. J. PHYS. ANTRROP., 31: 1-10. and by estimating the pattern and amount of gene flow among European populations. The east-west cline in the B blood group gene is illustrated on figures 1-3. The data are taken for the most part from Mourant et al. ( '58) , but the Spanish frequencies are from Guillen ('59), the French from Vallois and Marquer ('64), the Swedish from Beckman ('59), and the Finnish from Erikson et al. ('62). In Central Europe the abrupt rise in the B frequency occurs between the Germanic and Slavic peoples, although through Austria there seems to be a more gradual rise. On the other hand, through Scandinavia the rise is much more gradual. This may be due to the fact that in many parts of Sweden the population is almost 50% Finnish, which appears to be more gene flow than is found in Central Europe. In contrast to the east-west cline in the B frequency, figure 4 shows a northsouth transect which shows little if any change in either the A or €3 gene frequencies, However, as is shown in figure 4, stature does decrease from north to south in Europe. The data on stature are from Chamla ('64) and Lundman ('50). On figure 3 the cline in stature through Scandinavia is shown, but in this case it seems to be concordant with the cline in blood group B. For Scandinavia the data on stature are from Lundrnan ('50) and Kivalo ('57). In order to replicate the equilibrium frequencies of the blood group genes in