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The first step in biological evolution, according to the classical concept, was the ability of an organic entity, the gene, to duplicate itself by utilizing available inorganic molecules which themselves were incapable of reproduction. The next step was the acquisition by the gene of the property of catalyzing the production of a substance other than itself to be utilized as its host. In this way an aggregate of genes, each responsible for a specific reaction, could give rise to more complex structures. The manner of development of a simple organism would then depend upon the actions of the genes which it possessed. In this sense a gene which catalyzes a reaction which is necessary for an organism may be defined as an essential gene. It is this type, the essential gene, which has been considered to be of major significance in progressive evolution. In contrast to this widely accepted viewpoint, it is the intention of the present paper to show how the real materials for further evolution may be genes of another type, those which have lost their primary catalytic function while retaining their primary reproductive function and become neutral genes. These neutral genes have been spared from their essential roles by the taking over of their previous primary functions by the genes of other species. A neutral gene will be defined as a gene which may participate in the production of a substance, but the substance in turn is not essential to the organism. Such a gene is not necessarily inactive.

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Proceedings of the Iowa Academy of Science





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©1946 Iowa Academy of Science, Inc.



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