n. The act of selecting, choosing, or preferring; a choosing or picking out of one or more from a number; choice.n. A thing or number of things chosen or picked out.n. In biology, the separation of those forms of animal and vegetable life which are to survive from those which are to perish; the facts, principles, or conditions of such distinction between organisms; also, the actual result of such principles or conditions; also, a statement of or a doctrine concerning such facts; especially, natural selection. See phrases below.n. The fact of the survival of the fittest in the struggle for existence—which means that those animals and plants which are best adapted, or have the greatest adaptability, to the conditions of their environment do survive other organisms which are less adapted, or less capable of being adapted, to such conditions. This fact rests upon observation, and is unquestionable.n. The means by which or the conditions under which some forms survive while others perish; the law of the survival of the fittest; the underlying principle of such survival, and the agencies which effect that result. These seem to be mainly intrinsic, or inherent in the organism; and they are correlated, in the most vital manner possible, with the varying plasticity of different organisms, or their degree of susceptibility to modification by their environment. Those which respond most readily to external influence are the most modifiable under given circumstances, and consequently the most likely to be modified in a way that adapts them to their surroundings, which adaptation gives them an advantage over less favored organisms in striving to maintain themselves. Hence (and this is the gist of Darwinian natural selection)n. The gradual development of individual differences which are favorable to the preservation of the life of the individual, with corresponding gradual extinction of those peculiarities which are unfavorable to that end; also, the transmission of such modified characters to off spring, and so the perpetuation of some species and the extinction of others—a fact in nature respecting which there is no question, since we know that more species, genera, etc., have perished than are now living.n. The theory of natural selection; any statement of opinion or belief on that subject, which may or may not adequately reflect the facts in the case. Ignorance alike of these facts and of this theory has been fruitful of misunderstandings and objections respecting the latter. Some of its supporters have made of the theory a cause of the facts which it is simply designed to explain; some of its opponents, unconsciously biased perhaps by such other extremists, have denied that the theory has any validity. Between these extremes, the author of the theory states explicitly that it neither originates variability, nor accounts for the origin of variations, in individuals, still less in species; but that, given the origination and existence of variations, it shows that some of these are preserved while others are not; that favorable variations tend to be perpetuated and unfavorable variations to become extinct; that those variations which best adapt an organism to its environment are most favorable to its preservation; and, consequently, that the theory of natural selection is adequate to explain, to some extent, the observed fact of the survival of the fittest in the struggle for existence—that is, natural selection in sense above. Natural selection, in so far as sex is concerned, is specified as sexual selection (see below). The facts and principles of natural selection, as recognized and used by man for his own benefit in his treatment of plants and animals, come under the head of artificial selection (see above). An extension of the theory of natural selection to the origination (as distinguished from the preservation) of individual variations has been named physical selection (see below).n. Same as free-selection.n. In Australia, a station; land ‘selected’ or obtained cheaply from the government by a settler; a stock-farm.n. plural The highest grade of the heavy export tobacco. See export tobacco.n. A hypothetical struggle for existence among the here litary units in the chromatin of a germ-cell, and the survival of the fittest, and the corresponding modification of the germ-plasm or hereditary substance. See substance of heredity.
