A genetical formula for the inheritance of intelligence in man

Abstract

The inheritance of natural mental ability was first demonstrated statistically by Galton (1869) and his conclusions have since been considerably amplified and developed by Pearson (1904, 1919) and Woods (1906). So far no attempt has been made to express the problem in terms of a genetical formula, but recent progress in experimental psychology and genetics has made this possible. Material . Two distinct sets of material have been used in this investigation. (1) The cumulative results of a series of studies of the natural mental ability of the parents and offspring of 194 Leicestershire families continued through many years, which involved the personal investigation and gradings for intelligence of 388 parents and their 812 offspring, most of whom were recorded as adults. The same families were studied for the determination of the inheritance of Eye-colour in Man (Hurst, 1908, 1925). The material includes representative families of various classes and conditions of life in a rural manufacturing and agricultural district of South-west Leicestershire and provides a fair sample of the general population of the area, the only conscious selection exercised being large families of faithful matrons containing the highest and lowest grades of intelligence in the district. This material is distinguished as the L. F. data (Leicestershire families).