. Heredity and selection in sociology. Sociology; Heredity; Natural selection. 102 HEREDITY AND SELECTION IN SOCIOLOGY from its line of normality; in other words, it is only a minority of individuals who possess the organic characters which, in their totality, represent the biological equilibrium of the species; the majority have varied in a greater or less degree, and in a direction which disturbs the biological equilibrium by tending to bring the species out of harmony with its actual vital conditions. The result of this state of afEairs must either be a readaptation of the species to new co
. Heredity and selection in sociology. Sociology; Heredity; Natural selection. 102 HEREDITY AND SELECTION IN SOCIOLOGY from its line of normality; in other words, it is only a minority of individuals who possess the organic characters which, in their totality, represent the biological equilibrium of the species; the majority have varied in a greater or less degree, and in a direction which disturbs the biological equilibrium by tending to bring the species out of harmony with its actual vital conditions. The result of this state of afEairs must either be a readaptation of the species to new conditions, or the gradual extinction of the species. Asymmetrical curves are realised whenever, in response to a change of external conditions, the germ-plasm of the majority of individuals of a species enters into a period of instabihty and variation, pending the consolidation of O B D Fig. 6.—Asymmetrical Freqihency Cueve. The causes of asymmetrical curves, according to Ammon, are three in number : firstly, when the fertility of the species shows a tendency to increase among those groups of individuals which are nearer the limits of variation; secondly, when germinal selection tends to increase the rate of variation in a given direc- tion towards one or other of the poles; and thirdly, when natural selection intervenes in unequal proportions at one or the other of the poles. It may be remarked that the first cause is itself an effect of the second one; and the role of natural selection will be different according as the variation is useful to the species or not. If it be a variation tending to readapt the species to a changed en- vironment (to which the species is biologically adaptable), then. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Chatterton-Hill, Georges, 1883-. London : A. &
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