Passive Adaptation to the Physical Environment. Perfect adaptation to the physical environment would involve three conditions: first, individual survival; second, a reasonable degree of health; and third, continuous group survival through reproduction.

Individual survival. The chief means of adaptation to the physical environment is by the selective process. Those who cannot adapt themselves are eliminated, while the more adaptable survive and reproduce their kind, their offspring inheriting their superior powers of adaptation. The selective process is seen most clearly where individuals or groups have moved from one environment to a very different environment, such as the English to India, the Americans to the Philippine Islands, or the Negroes from the southern to the northern states. Such migrations are followed by a higher rate of mortality than was common in the previous environment, indicating the elimination of those incapable of adjusting themselves to the changed conditions. The selective process is however always operating to some extent among peoples who remain in a given environment. Infants varying from the normal in such ways as to make adaptation impossible are eliminated; and only those survive who possess the necessary characteristics for adaptation. This continuous process of adjustment is one of the factors in a high infant mortality.

In addition to the method of selection through elimination another less extreme process of adaptation may also be detected. If changes in the environment are moderate the average individual undergoes certain physical alterations, which after a time leave him better adapted to the new environment than he was at first. Modifications of this kind are made in such cases as changes in altitude or in climate. The body becomes adjusted to new conditions and may then function just as well as in the previous environment. Such bodily changes represent the process of adaptation in those who survive. Those who are unable to make the physical adaptations are much more likely to be eliminated.

Health. The second test of adaptation simply means that individuals who do adapt themselves to a new environment

should not merely survive but should show a reasonable amount of health and vitality under the new conditions. The standard of vigor however cannot be made that of the previous environment, because some climates are much less stimulating to everyone than other climates. The standard must be found rather in the average energy of the native population. The point involved here is that some persons in changing their environment undergo what may be called a partial adaptation. With care they are able to survive; but they never show the health and vigor which could be expected in that particular location.

Group survival. The third evidence of adaptation, the power of reproduction, is a racial rather than an individual matter. The fact, which is not well understood, seems to be that certain people who live in a new environment in comparative health are unable to rear there such a healthy and numerous offspring as they could have in their native environment. The difficulty may be merely a matter of the survival of infants rather than the numbers born. But if a people are unable to keep up their numbers in a particular environment from any cause whatsoever, they cannot be said to be adapted fully to that environment. An example is that of the English in India who are moderately well adapted in the first two ways but are not yet adapted in the racial sense. In fact Professor Robert Dec. Ward says, “ Acclimatization in the full sense of having

1 white men and women living for successive generations in the tropics and reproducing their kind without physical, mental, and moral degeneration, - i.e. colonization in the true sense, — is impossible.”

Active Adaptation to the Physical Environment. Passive adaptation, at least in its more extreme forms, is being continually resisted by man, who seeks to avoid the painfulness of the selective process by quicker and more agreeable methods of adaptation. For this reason man alters the environment in numberless ways to make it better suited to his needs. He cuts down forests to clear the land; he drains or irrigates land to increase food supply; he dredges harbors and rivers, and

builds highways, to transport food and other commodities and to permit a better distribution of the population; and finally he destroys injurious animal and vegetable life to decrease directly disease and death.

Notwithstanding man's ingenuity in the adaptation of nature to his needs, certain natural forces like climate he is unable to alter, so he builds houses, wears clothing, and in other ways protects himself from the deleterious effects of these forces. These protective measures should be distinguished from active adaptation proper. They fail to change the natural environment. It remains as it was. But they relieve man to some extent from the necessity of submitting to passive adaptation. Hence protective products of industry should be classed as intermediate measures between active and passive adaptation. They are properly superorganic products and belong to the social environment.

Adaptation to the Social Environment. Superorganic products. Adaptation to superorganic products is still so imperfect that elimination is of frequent occurrence. The greater part of the excessive death rate in cities is due to this defect rather than to imperfect adaptation to the physical environment. Deaths due to insanitary tenements or to other adverse living conditions, deaths due to impure foods, to accidents in factories and on railroads, are all examples of this kind of poor adaptation. The remedy for such unfortunate conditions does not lie of course in passive adaptation at all, but in a change in the character or the use of the products of industry. These products are designed to protect man from the physical environment; but when they themselves prove a cause of death, it is evident that they are not performing their proper function, and they should be altered to become true preservers, not destroyers of life. Inasmuch as active adaptation would seem to be superior to passive, the conclusion might be drawn that it should be uniformly favored; but the exclusive use of active adaptation is not always possible. In deciding which method should be employed we must consider first whether it is feasible to alter the environment, and, second, whether the action of an environment is truly selective; that is, whether it eliminates the inferior

physically and socially and permits the superior to survive. In making the choice we must bear in mind also the fact that passive adaptation is costly in life, and active adaptation is costly in labor. It is conceivable that individuals could be evolved adapted to dark and insanitary tenements; in fact, the Jews now show greater powers of survival under such adverse conditions than do other races. But such a process would not ensure the survival of the socially superior, and hence it would involve unnecessary cost in human life and therefore be useless. Deaths from such calamities as railroad accidents furthermore are not selective in their action at all. In all such cases therefore the method to be employed to ameliorate conditions is furtherance of active rather than of passive adaptation.

Adaptation to superorganic products, like that to the inorganic environment, takes place in various ways less extreme than elimination. New methods of production affect our occupations and permit the existence of larger populations; improved means of communication increase social contacts and affect our thoughts and our behavior, alter the character of our dwellings, and influence our social life. We produce certain things when we believe we are ready to utilize them; but, having produced them we are often obliged to adapt ourselves to them in indirect and unforseen ways.

The human environment. Adaptation of men to other members of a group is more perfect than it is to superorganic products; and actual elimination through it is comparatively infrequent, though deaths from suicide or homicide show that even in social relations the elimination of the unfit does occur. In the process of adaptation of men to one another within the group the active and passive forms are not easily distinguished in practice. Individuals and society give and take. Occasionally an individual succeeds in impressing society with his own views and consequently modifies its activities; but the more evident process is the molding of the individual by society in conformity with it; and for this purpose society uses the forces of law, of education, and of public opinion. Of course individuals may alter society more easily if they occupy positions of authority; for otherwise they must make continued appeals to the reason or to the emotions of others until the minority becomes the majority, or until those in authority are won over. Adaptation of groups or nations to one another is in a much more rudimentary stage, as is shown by the continual recurrence of war with the resulting subjection or absorption of the vanquished.

Conclusion. From this brief outline it appears that in the course of social evolution adaptation to the physical environment, represented broadly by economic activities, is predominant at first; but that later, as social and mental products increase, adaptation to the social environment becomes relatively more important. This does not mean of course that economic activities cease or that physical adaptation is perfected; but that development is realized more and more through cultural activities. Physical adaptation continues to be the more important from the point of view of survival, but social adaptation is of more importance from the point of view of evolution. Progress through the increase in social products and through the perfection of social relations may be limitless.

REFERENCES FOR COLLATERAL READING
BRISTOL, L. M., Social Adaptation.
CARVER, T. N., Sociology and Social Progress., Introduction.
KELLER, A. G., Societal Evolution.
KELSEY, C., The Physical Basis of Society.
PATTEN, S., The Theory of Social Progress.