And, although a quantitative statement of the relative importance of the two factors implies a more accurate solution of the problem than has been actually obtained, it is nevertheless worth repeating in the summary that measurements made showed that the resemblance of individual characters in offspring to those of parents was from 5 to 10 times as great as conformity between individual characters and environmental conditions. Starch states it a little more conservatively when he says that? “the ultimate achievement of any given individual is due to his original ability, probably to the extent of 60 to 90% and to actual difference in opportunity or external circumstances only to the extent of 10 to 40%.

The True Nature of Environmental Influence. Further analysis is needed here of the action of the environmental factors, lest their influence seem to be underrated. Although investigations show that nature is more important than nurture in determining existing differences in men, in favor of nurture it should be said that it furnishes the stimulus for absolute achievement and it determines also the direction of development. Thorndike has summarized the methods whereby environment acts upon intellect and morals as follows: 2

1. Furnishing or withholding the physiological conditions for the brain's growth and health.

2. Furnishing or withholding adequate stimuli to arouse the action of which the brain is by original nature or previous action capable.

3. Reënforcing some and eliminating others of these activities in consequence of the general law of selection in mental life.

The first result is of special importance during the early years of growth. F. W. Mott 3 has laid particular emphasis on the health of the mother, the proper nourishment of the child, and sufficient sleep, as factors essential for the full development of mental as well as physical energy. Low powers of attention and quick fatigue may result from bad nurture.

The second set of forces may act at any or all periods of life,

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and they are of great importance in stimulating men to their highest capacities. Few people develop latent abilities to the fullest extent possible; and for the great majority of men environmental improvements providing effective stimuli will yield the richest results. The reason why so many persons drift through life on low tension is because they have not been gripped by an absorbing interest. Their dormant abilities have never been roused by the right environmental stimuli. One method of salvaging this wasted force is through improvement in the educational system. If schools could ascertain the individual capacities of pupils and bring to bear the right stimuli to develop those capacities, and if they could arouse permanent interests in the young which would direct their life work, they would add much to the total energy available for society. Such educational work is much more fundamental and profitable than insistence on the mere memorizing of conventional facts in a wider and wider range of subjects.

Another way of developing latent talent would be to improve methods of adjusting individuals to occupations; or rather to provide a method, for at present choice of occupations is almost haphazard. The chief stimulus to man's activity and effort comes from his occupation, and it is therefore of great importance that it should arouse his interest and suit his capacity. Recent developments in the line of vocational training are promising; but a more comprehensive system is needed to adjust workers to the economic needs of society in place of mere reliance upon price fluctuations through variations in demand and supply. The present mal-adjustment has two phases. First, too large a number of young people have no wide choice of occupations. They are obliged at an early age to enter any employment which opens to them, even before, perhaps, their individual aptitudes are apparent. Second, there is the limi. tation due to ignorance of occupational possibilities. A wider spread knowledge of what the various callings mean, of the characteristics requisite for success in them, and of the possibilities they offer for advancement and for achievement, would be of inestimable value to young people in choosing their occu. pations.

And finally, it should be added that the majority of workers lack any real interest, or any real incentive for achievement, in their chosen occupations. The ordinary incentive for exertion in economic life, even among the most diligent, arises out of the instinct of acquisitiveness rather than from any aspiration to increase efficiency or to perfect economic organization. Desire for gain may be a strong incentive in any occupation, and, since it stimulates ambition, may easily be mistaken for devotion to the work itself. And while society may profit indirectly from the efforts of individuals to acquire, it would realize a greater gain if the stimulus came from direct interest in vocations. Let the individual find the stimulus for his faculties in his occupation itself, or better still let his absorbing interest become his occupation.

The third effect mentioned by Thorndike refers to the possibility of suppressing or stimulating mental traits through environmental action. Each individual is a bundle of desirable and undesirable traits; or, at least, each harbors within himself possibilities which may develop either into useful or into antisocial traits; although it must be borne in mind in this connection that mental characters useful in one stage of social organization may become harmful in another, so that social utility should be the guide in the selection of mental and social traits. Now external stimuli which tend to draw out desirable and check undesirable qualities are collectively known as good environmental influences; and these it is partly within our power to create.

An attribute of a favorable environment less frequently considered is its capacity to stimulate to activity many, or indeed all, good qualities instead of a few only. To accomplish the best results an environment should be as varied as possible. How often do we see environments which are not evil, to be sure, but merely narrow; whose products are not vicious, but warped or dwarfed, - if such a distinction may be made. A study of all the natural qualities of man, and their favorable relationship in the well-rounded individual, together with a knowledge of the external conditions necessary to mature these characteristics, might easily become a separate science of the environment.

Final Considerations. If the weight of evidence in a comparison of nature and nurture is in favor of nature as the more powerful determinant, still an analysis of the functions of the environment must convince us that the improvement of the environment is by no means a futile reform. Although the environment cannot as a rule affect native qualities, it may influence the health and energy of a child, and it may determine the degree to which inherent characters shall be developed or perfected, and lastly it may exert a selective influence in favor of the development of one trait over another.

Finally it should be added that, of the two agents in social regeneration, the environment is much more easily modified than is the racial stock. In so far as the generation living is concerned native traits are fixed. We must take them as they are and make of them as much as is possible by the use of environmental stimuli. To alter the racial stock is at best a slow process, the results appearing only from generation to generation; but environmental action is direct and immediate for each generation, and for good or for ill its influence is continually at work.

REFERENCES FOR COLLATERAL READING CASTLE, W. E., Genetics and Eugenics. CONKLIN, E. G., Heredity and Environment in the Development of

Men. ELDERTON, E. M., Relative Strength of Nature and Nurture. GALTON, FRANCIS, Inquiries into the Human Faculty. McBRIDE, E. W., The Study of Heredity, Eugenics Review, Vol. 8. Mort, F. W., Nature and Nurture. NEWMAN, H. H., Readings in Evolution, Genetics, and Eugenics. POPENOE, P., Nature or Nurture, Journal of Heredity, 6:227. POPENOE and JOHNSON, Applied Eugenics, Chs. I and 2. SCHUSTER, E., Eugenics, Ch. 9. THORNDIKE, E. L., Educational Psychology. WALLACE, A. R., Social Environment and Moral Progress. WARD, L. F., Applied Sociology.

CHAPTER XXIV

GENETIC SELECTION

Definition. Genetic or reproductive selection, as defined by Pearson, is selection by relative productivity. Applied to plant and animal life, this means that the most fertile determine most strongly the character of future generations. Applied to the human species, genetic selection is more than a matter of natural fertility, for mere potential fertility does not always determine relative rates of reproduction. Individuals or classes in society which for any reason, physical or social, multiply the most rapidly will impress themselves most strongly on the society of the future and will transmit to it their particular characteristics. In other words society in the long run gradually leans in the direction of those that reproduce most rapidly.

The Problem Stated. It may be said at the outset that genetic selection has come to be the most important form of selection in advanced societies, and that the problems connected with it are among the most significant of all those confronting society at the present time. In a previous chapter it has been shown that the natural effects of inorganic selection have been partially counteracted by the growth of sympathy and responsibility towards others; that the action of heterogeneric selection is being gradually lessened by the progress of science; and that autogeneric selection now results in only a small selective death rate. With this passing of the different forms of natural selection, through increasing control of the death rate, the problem of the progressive improvement of the race must depend upon genetic selection through control of the birth rate. Even now society is approaching a crisis in its method of evolution. In learning to control external nature man is freeing himself from the relentless action of natural selection, but he has not yet substituted for it the system of intelligent cultivation. Blind