Quotes About Species

I do not believe, as we shall presently see, that all our dogs have descended from any one wild species; but, in the case of some other domestic races, there is presumptive, or even strong, evidence in favour of this view.

I am fully convinced that species are not immutable; but that those belonging to what are called the same genera are lineal descendants of some other and generally extinct species, in the same manner as the acknowledged varieties of any one species are the descendants of that species. Furthermore, I am convinced that natural selection has been the most important, but not the exclusive, means of modification.

Sexual selection acts in a less rigorous manner than natural selection. The latter produces its effects by the life or death at all ages of the more or less successful individuals.

To admit that species generally become rare before they become extinct—to feel no surprise at the comparative rarity of one species with another, and yet to call in some extraordinary agent and to marvel greatly when a species ceases to exist, appears to me much the same as to admit that sickness in the individual is the prelude to death—to feel no surprise at sickness—but when the sick man dies to wonder, and to believe that he died through violence.

This preservation of favourable variations and the rejection of injurious variations, I call Natural Selection.

I fully agree with all that you say on the advantages of H. Spencer's excellent expression of 'the survival of the fittest.' This, however, had not occurred to me till reading your letter. It is, however, a great objection to this term that it cannot be used as a substantive governing a verb; and that this is a real objection I infer from H. Spencer continually using the words, natural selection. (Letter to A. R. Wallace July 1866)

This preservation of favourable individual differences and variations, and the destruction of those which are injurious, I have called Natural Selection, or the Survival of the Fittest.

Charles Darwin

Sexual selection will also be largely dominated by natural selection tending towards the general welfare of the species.

We will now discuss in a little more detail the Struggle for Existence

Showing that they descend from common parents, and consequently must be ranked as varieties.

El aislamiento también es un elemento importante en la modificación de las especies por medio de la selección natural. En un área limitada o aislada, si no es muy grande, serán generalmente casi uniformes las condiciones orgánicas e inorgánicas de la vida, de modo que la selección natural tenderá a modificar de la misma manera a todos los individuos que varíen en la misma especie.

Charles Darwin

Who can explain why one species ranges widely and is very numerous, and why another allied species has a narrow range and is rare? Yet these relations are of the highest importance, for they determine the present welfare, and, as I believe, the future success and modification of every inhabitant of this world.

I can entertain no doubt, after the most deliberate study and dispassionate judgment of which I am capable, that the view which most naturalists entertain, and which I formerly entertained—namely, that each species has been independently created—is erroneous.

puede llegar a deducir que las especies no han sido creadas independientemente, sino que han descendido como variedades de otras especies.

As the species of the same genus usually have, though by no means invariably, much similarity in habits and constitution, and always in structure, the struggle will generally be more severe between them, if they come into competition with each other, than between the species of distinct genera.

immutable productions

Judging from the past, we may safely infer that not one living species will transmit its unaltered likeness to a distant futurity.

like varieties, from other species. Nevertheless, such a conclusion, even if well founded, would be unsatisfactory, until it could be shown how the innumerable species inhabiting this world have been modified, so as to acquire that perfection of structure and coadaptation which most justly excites our admiration. Naturalists continually refer to external conditions, such as climate, food, etc., as the only possible cause of variation. In one very

Charles Darwin

In a series of forms graduating insensibly from some apelike creature to man as he now exists, it would be impossible to fix on any definite point where the term 'man' ought to be used.

Why is The Origin of Species such a great book? First of all, because it convincingly demonstrates the fact of evolution: it provides a vast and well-chosen body of evidence showing that existing animals and plants cannot have been separately created in their present forms, but must have evolved from earlier forms by slow transformation.

It was evident that such facts as these, as well as many others, could only be explained on the supposition that species gradually become modified; and the subject haunted me.