vestigations of Boas and Wissler that unfavorable environmental influences which cause a child to grow slowly during a number of years act as retarding causes such that the child will probably continue to grow more slowly than other, normal children. Even at completed growth the child is smaller than its normal companions. On the other hand, children who have had their growth accelerated by favorable surroundings reach the adult stage earlier and attain a relatively greater size and development. Thus the absolute size and the relative proportions of the body are influenced by periods of retardation or acceleration. These periods of change in the rate of growth appear to be due to such retarding causes as: illness in early childhood, malnutrition, lack of fresh air and physical exercise, to the influences of environment, physical and social. The conclusion to be drawn from this body of evidence is that environment is most potent as a modifying cause in early plastic years. On the other hand, there are now available several studies of considerable importance which seem to show that environment is not such an important factor in the development of children. These investigations have been made by the Galton Laboratory for National Eugenics of the University of London, under the direction of Professor Karl Pearson. The inheritance of vision and the relative influence of heredity and environment on sight have been studied and the statisticians have reached the following conclusions from their admittedly slender data: (1) No evidence whatever that over-crowded, poverty-stricken homes, or physically 8 Boas, F., and Wissler, C.-Statistics of Growth, Report of U. S. Commissioner of Education for 1904, pp. 25-132. 9 Eugenics Laboratory Memoirs, V. 99 10 ill-conditioned, or immoral parentages are markedly detrimental to the children's eye-sight; (2) No sufficient or definite evidence that school environment has a deleterious effect on the eye-sight of children; (3) Ample evidence that refraction and keenness of vision are inherited characters. When it is considered that this study was undertaken in anticipation of finding that inheritance and environment factors would be far more comparable in magnitude, it is evident that the investigation was pursued without bias. A second study, of the influence of defective physique and unfavorable home environment on the intelligence of school children, showed that there was "no sign of an environmental condition producing an effect on the mentality of the child at all comparable with the known influences of heredity. This investigation also appears to have been undertaken with an open mind. Finally, the controversial "Study of the Influence of Parental Alcoholism on the Physique and Ability of the Offspring," 11 peared to show that there was no marked relation between intelligence, physique or disease of the offspring and parental alcoholism in any of the categories investigated. For example, the study showed that the average weight and height of the children of alcoholic parents was slightly in excess of that of children of sober parents; the general health of the children of alcoholic parents appeared to be slightly better than the health of children of sober parents. However completely subsequent investigations may correct or confirm the conclusions of the London eugenists, certain it is that in the present stage of our knowledge we can make no dogmatic statements 10 Eugenics Laboratory Memoirs, VIII, p. 60. 11 Eugenics Laboratory Memoirs, X. ap as to the absolute effect of environment, and until we have made more comprehensive investigations it is best to leave the matter open. A study of the direct influence of environment upon the bodily form of man was made in 1908 and 1909 by Professor Boas.12 Four groups of people were investigated; the south Italians, representing the Mediterranean type of Europe, characterized by short stature, elongated head, dark complexion and hair; the central European type, characterized by medium stature, short head, light hair and lighter complexion; the northwest European type, characterized by tall stature, elongated head, light complexion, and blond hair; and in addition, an extended series of east European Hebrews, who resemble in some respects the central European group. The traits selected for examination were head measurement, stature, weight, and hair-color. The result of the inquiry was to show that the American-born descendants of these types differ from their parents; and that these differences develop in early childhood and persist throughout life. It was found that head form, which has always been considered as one of the most stable and permanent characteristics of human races, undergoes far-reaching changes due to the transfer of the races of Europe to American soil. The east European Hebrew, who has a very round head, becomes more long-headed in the first generation born in America; the south Italian, who in Italy has an exceedingly long head, becomes more short-headed in the first generation born in Amer. ica; so that both approach a uniform type in this country, 12 Changes in Bodily Form of the Descendants of Immigrants, The Immigration Commission, 61st. Cong., 2d Session, Doc. no. 208; see also The Mind of Primitive Man, ch. ii, for discussion. |