Value of anteroposterior radiography in cervical pain of non-traumatic origin.

Comment The fall in differences in height between groups varying in intelligence and educational level is probably attributable to changing social factors,perhaps specifically a greater homogeneity of nutritional conditions across different social classes. In earlier data we found that the social class of parents correlated with the intelligence (0 32) and educational level (0 42) of their children. In the present data for 1939-58 the correlation between intelligence and educational level was 073. The decline in differences among grou'ps and the corresponding correlations seemed to be most pronounced among those generations who were in their infancy during the 1940s. The decline thereafter was less pronounced. Whether such differences will disappear remains to be seen, particularly as the increases in height seem to be ending. Records of the Danish draft board show the average height of men to have remained virtually stable at about 180 cm for almost the past 10 years. The differences may, however, never entirely disappear. As there are important genetic contributions to both height and intellectual ability possibly the association between the two results in part from the influence of pleiotropic genes. The relations, however, are not overwhelming. The multiple correlation of height with the score on intelligence testing and educational level for the 1954-8 cohort was 0-238 (table), and thus these two factors together accounted for less than 6% of the variance for height.