2. Biological differences between human beings reflect both hereditary factors and the influence of natural and social environments. In most cases, these differences are due to the interaction of both. The degree to which environment or heredity affects any trait varies greatly.
3. There is great genetic diversity within all human populations. Pure races, in the sense of genetically homogenous populations, do not exist in the human species today, nor is there any evidence that they have ever existed in the past.
4. There are obvious physical differences between populations living in different geographic areas of the world. Some of these differences are strongly inherited and others, such as body size and shape, are strongly influenced by nutrition, way of life, and other aspects of the environment. Genetic differences between populations commonly consist of differences in the
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Wherever different human populations have come in contact, such mattings have taken place. Obstacles to such interaction have been social and cultural, not biological. The global process of urbanization, coupled with intercontinental migrations, has the potential to reduce the differences among all human populations.
8. Partly because of gene flow, the hereditary characteristics of human populations are in a state of perpetual flux. Distinctive local populations are continually coming into and passing out of existence. Such populations do not correspond to breeds of domestic animals, which have been produced by artificial selection over many generations for specific human purposes.
9. The biological consequences of mating depend only on the individual genetic makeup of the couple, and not on their racial classifications. Therefore, no biological justification exists for restricting intermarriage between persons of different racial