Changes of selection opportunities with a changing environment: regional heterogeneity in Italy.

The mortailty and fertility components of the index of opportunity for selection (the Crow index) have been studied in the various Italian regions during the last century. To estimate the relevance of environmental factors on both components, their trends and those of their interregional variances have been compared with illiteracy. The results show that the selection opportunities due to mortality have decreased in a smiliar way in all the regions with a trend parallel to that of the national percentage of illiteracy, suggesting that this component is directly affected by the general socio-cultural level. As to the component due to fertility differentials, the regions, though scattered in the time scale, show a characteristic cycle of rise and fall. Moreover, the interregional variances of this component and of illiteracy are quite parallel, thus supporting the hypothesis that the reproductive pattern is strongly influenced by the individual cultural level.