Government might also be added, because there is a tendency to consider the people who live under a single government as allied in race. Yet after all is not mental and moral character more important than any other factor in differentiating race from race? One race holds aloof from another largely because each one, rightly or wrongly, believes that the other is somehow in- ferior or perhaps superior; and these terms generally mean of less or greater mental ability and energy. These mental differ- ences are what we want to study.

In the strictest sense of the word, races should be defined only in terms of heredity. But certain geographical factors, such as climate, food, and occupations, have a distinct effect in changing racial characteristics. They cause people to grow up with cer- tain habits; they also select certain types for preservation and eliminate others. Thus the fishing industry tends to eliminate people of a timid disposition. Such people may succeed as fann- ers, but not on the sea. Hence, in course of time, perhaps a very long time, each environment and each occupation tends to make its people slightly different from those in other environments and other occupations. Moreover, social conditions such as religion, language, government, education, and local customs have a great deal to do with determining a people’s character. They play a part not only in controlling the training of children and youth, but in determining what types of people shall interrnarry, what types shall have large families, and what types shall die out. Thus physical and social conditions may have a great effect upon human character both directly and through inheritance. Hence the character of specific groups of mankind depends on inheri- tance, physical environment, and social environment. Our task is to attempt to show how far these two types of environment select certain kinds of character for preservation or destruction and thus cause certain mental characteristics to become a per- manent part of the racial inheritance.

From the biological standpoint we are quite certain that the inherent mental and physical differences between one race or stock and another are largely due to three chief causes: first, sudden mutations, or possibly small but progressive deviations

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