THE GEOGRAPHICAL DISTRIBUTION OF ANIMALS
By William Berryman Scott
Blair Professor of Geology and Paleontology, Princeton University
Possible Explanations of Geographic Distribution
Different kinds of animals are found in different lands or in different seas. Even the animals of the same continent may show great differences, such as those between the animals of the Canadian forests and those of the coast of the Gulf of Mexico. A hasty examination of the facts might lead to the conclusion that animals were spread over the earth altogether in adaptation to climatic conditions, but this would be a mistake, for climate is only one factor in a very complicated problem, and similarity of climate in widely separated lands is insufficient in itself to bring about similarity of animals. The tropical parts of Australia, Africa, and South America have very similar climates, but their animals are altogether different. Climate, however, may be an effective barrier to the spread of animals and plants, but its action in this respect is entirely negative.
Two alternative views concerning the origin of new forms of life, animal or vegetable, have been presented. One, the older view, which generally prevailed until the publication of Darwin’s Origin of Species, in 1859, was that each kind of animal and plant had been separately created and was, within certain narrow limits, unchangeable and immutable.
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