A Quote by Stephen Jay Gould
The basic formulation, or bare-bones mechanics, of natural selection is a disarmingly simple argument, based on three undeniable facts (overproduction of offspring, variation, and heritability) and one syllogistic inference (natural selection, or the claim that organisms enjoying differential reproductive success will, on average, be those variants that are fortuitously better adapted to changing local environments, and that these variants will then pass their favored traits to offspring by inheritance).
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You put three facts together - that all organisms produce more offspring that can survive, that there's variation among organisms, and that at least some of that variation is inherited - and the syllogistic inference is natural selection.
Natural selection is just three factors - over-production, variation, and inheritance combined to produce adaptation to changing local environments. It's not a principle or progress; it's just a principle of local adaptation. You don't make better creatures in any cosmic sense; you make creatures that are better suited to the changing climates of their local habitats.
Natural selection may lead to benefits for species, but these `higher' advantages can only arise as sequelae, or side consequences, of natural selection's causal mechanism: differential reproductive success of individuals.
Throughout his last half-dozen books, for example, Arthur Koestler has been conducting a campaign against his own misunderstanding of Darwinism. He hopes to find some ordering force, constraining evolution to certain directions and overriding the influence of natural selection. [...] Darwinism is not the theory of capricious change that Koestler imagines. Random variation may be the raw material of change, but natural selection builds good design by rejecting most variants while accepting and accumulating the few that improve adaptation to local environments.
The reason for natural selection's great success is that it provides a satisfying explanation of how evolution might have occurred: individual organisms vary, and if those variations are inherited, the successful ones will survive and propagate and pass down their desirable traits to succeeding generations.
The essence of Darwinism lies in its claim that natural selection creates the fit. Variation is ubiquitous and random in direction. It supplies raw material only. Natural selection directs the course of evolutionary change.
Natural selection is a blind and undirected consequence of the interaction between variation and the environment. Natural selection exists only in the continuous present of the natural world: it has no memory of its previous actions, no plans for the future, or underlying purpose.
Quantitative work shows clearly that natural selection is a reality, and that, among other things, it selects Mendelian genes, which are known to be distributed at random through wild populations, and to follow the laws of chance in their distribution to offspring. In other words, they are an agency producing variation of the kind which Darwin postulated as the raw material on which selection acts.
In the wild, those traits that are adaptive for survival and reproductive advantage are brought out through natural selection. So cats that were fierce, furtive hunters, alert to the snapping of every twig, with coats that gave them good camouflage, would have been favored by evolution.
Natural selection is a theory of local adaptation to changing environments. It proposes no perfecting principles, no guarantee of general improvement
Trait X is fitter than trait Y in a population of organisms if those organisms have other biological traits T and live in an environment that has properties E. The theory of natural selection is filled with statements of this form.
The theory of natural selection is the centerpiece of The Origin of Species and of evolutionary theory. It is this theory that accounts for the adaptations of organisms, those innumerable features that so wonderfully equip them for survival and reproduction; it is this theory that accounts for the divergence of species from common ancestors and thus for the endless diversity of life. Natural selection is a simple concept, but it is perhaps the most important idea in biology.
Darwinian natural selection only yields adaptation to changing local environments, and better function in an immediate habitat might just as well be achieved by greater simplicity in form and behavior as by ever-increasing complexity.
Natural Selection is not Evolution. Yet, ever since the two words have been in common use, the theory of Natural Selection has been employed as a convenient abbreviation for the theory of Evolution by means of Natural Selection, put forward by Darwin and Wallace. This has had the unfortunate consequence that the theory of Natural Selection itself has scarcely ever, if ever, received separate consideration.
This fundamental subject of Natural Selection will be treated at some length in the fourth chapter; and we shall then see how Natural Selection almost inevitably causes much Extinction of the less improved forms of life and induces what I have called Divergence of Character.
Evolution by natural selection is not an idle hypothesis. The genetic variation on which selection acts is well understood in principle all the way down to the molecular level.
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