Much has been said of the hereditary characteristics of the Jews, of the Gypsies, of the French and Irish, but I do not see that the external and social causes which have moulded the character of members of these people have ever been eliminated satisfactorily; and, moreover, I do not see how this can be accomplished. A number of external factors that influence body and mind may easily be named--climate, nutrition, occupation--but as soon as we enter into a consideration of social factors and mental conditions we are unable to tell definitely what is cause and what is effect. * * * * * The conclusions reached are therefore, on the whole, negative. We are not inclined to consider the mental organization of different races of man as differing in fundamental points. Although, therefore, the distribution of faculty among the races of man is far from being known, we can say this much: the average faculty of the white race is found to the same degree in a large proportion of individuals of all other races, and although it is probable that some of these races may not produce as large a proportion of great men as our own race, there is no reason to suppose that they are unable to reach the level of civilization represented by the bulk of our own people.[1] [Footnote 1: Boas; _loc. cit._, pp. 116, 123.] In contrast must be cited the opinions of a large class of psychologists and anthropologists who are inclined to regard racial differences as intrinsic and original. Of such, for example, is Francis Galton, who claims in his _Hereditary Genius_, that taking negroes on their own ground they still are inferior to Europeans by about one eighth the difference, say, between Aristotle and the lowest idiot. Recent psychological experiments in the army reveal, again, certain fundamental intellectual inferiorities of negroes, though whether this is environmental or to be traced to hereditary causes is open to question. The fact remains that there are, despite the lack of evidence for hereditary mental differences, practical differences in the mental activity of different races that are of social importance. These differences, which seem so fundamental, have been explained primarily by the powerful control exercised over the individual by the habits which he acquires even before the age of five years. These, though unconscious, may be, as the Freudian psychologists maintain, all the more important for that reason. This would appear to be the only explanation of significant racial differences. Cultural differences cannot, biologists are generally agreed, be transmitted in the germs that pass from generation to generation. One may say, in effect, that an individual is differentiated in his mental traits by early association with a certain race, and by his immediate ancestry or family, rather than by the fact of belonging physically to a certain race.