GENETICS OF HUMAN MIND 413 



of intelligence tests to adults in general. It is to be hoped that more refined 

 and accurate methods of grading adult intellect will be devised by psy- 

 chologists which are based on achievements in life rather than on the scores 

 obtained in set mental tests. It is evident that neither "Alpha" nor "Beta" 

 tests can be effectively applied to adults in times of Peace. 



Still less can these experimental tests be applied to historical persons like 

 Woods' Royalties and the three hundred geniuses of Dr. Catherine Cox 

 (1926). Cox's remarkable work in estimating the I.Q.'s of 300 geniuses 

 from the evidence of their Juvenilia, leads one to hope that she may be per- 

 suaded to attempt to grade their intellects on the evidence of their achieve- 

 ments in adult life. 



The great value of a battery of standardised mental tests for estimating 

 the I.Q.'s of juveniles and adolescents is beyond all doubt, and for the benefit 

 of posterity such standardised tests should be made compulsory in all 

 schools, so that in course of time the I.Q.'s of all the adults in future popula- 

 tions would be approximately known. 



GENETICAL FORMULA FOR INTELLECT 



For many years the data obtained from the Leicestershire families and 

 those of Woods from the Royal families were studied and restudied but no 

 satisfactory genetical formula could be devised that would cover the whole 

 of the data. In 1931, however, an English translation of a Russian paper 

 on Wheat was made by Dr. Hudson of the Imperial Bureau of Plant Genetics 

 Cambridge and accidentally came into my hands, which gave a clue to the 

 solution of the human problem. This paper was a report by the Russian 

 geneticist Philiptschenko, dated 1927, giving the results of a complete ge- 

 netical analysis of the characteristic broad grains and glumes of the famous 

 "Marquis" Wheat. After many years of experimental breeding Philipt- 

 schenko succeeded in identifying the six pairs of genes which in combina- 

 tion produce this super- variety of Wheat. An application of this hexagenic 

 formula for Wheat to the human family data for intellect showed that it 

 covered the data sufficiently well to warrant its being used as a working 

 hypothesis for the genetics of intellect. 



Table 2 explains the genetical formula and its application and adjustment 

 to the human data. It consists of a basic pair of genes with five pairs of 

 modifiers. Although superficially complex it is fundamentally simple in its 

 working. 



On the basis of this formula it is possible to predict the grades of offspring 

 that each grade will produce when mated with its own or any other grade, 

 except that the matings of the mediocre grade 5 will give a different result 

 whether they are nn, NN, or Nn. 



