A Quote by Stephen Jay Gould

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 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 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.
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).
In fact, nothing in science as a whole has been more firmly established by interwoven factual information, or more illuminating than the universal occurrence of biological evolution. Further, few natural processes have been more convincingly explained than evolution by the theory of natural selection, or as it has been popularly called, Darwinism.
Natural selection is a theory of local adaptation to changing environments. It proposes no perfecting principles, no guarantee of general improvement
When environments change, they usually do so pretty rapidly, at rates with which adaptation by natural selection would be hard put to keep up. When such change occurs, the quality of your adaptation to your old habitat is irrelevant, and any competitive advantage you might have had may be eliminated at a stroke.
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.
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.
Darwinian evolution is slow and gradual, step by step. Such an evolution can explain micro-evolution but not macro-evolution. For example, how did the eye evolve? The idea behind Darwinism is that organisms adapt, and that nature selects only those genetic changes which are the mutations that serve a good purpose for adaptation. So taken this way, the eye cannot develop gradually because one-thousandth or one-millionth of an eye would be of no value for survival. So generally this question rules out Darwinism as an adequate theory for macro-evolution.
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.
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.
Group selection and individual selection are just two of the selection processes that have played important roles in evolution. There also is selection within individual organisms (intragenomic conflict), and selection among multi-species communities (an idea that now is getting attention in work on the human microbiome). All four of these levels of selection find a place in multi-level selection theory.
A complete theory of evolution must acknowledge a balance between "external" forces of environment imposing selection for local adaptation and "internal" forces representing constraints of inheritance and development. Vavilov placed too much emphasis on internal constraints and downgraded the power of selection. But Western Darwinians have erred equally in practically ignoring (while acknowledging in theory) the limits placed on selection by structure and development what Vavilov and the older biologists would have called "laws of form.
The positive evidence for Darwinism is confined to small-scale evolutionary changes like insects developing insecticide resistance....Evidence like that for insecticide resistance confirms the Darwinian selection mechanism for small-scale changes, but hardly warrants the grand extrapolation that Darwinists want. It is a huge leap going from insects developing insecticide resistance via the Darwinian mechanism of natural selection and random variation to the very emergence of insects in the first place by that same mechanism.
Charles Darwin got his theory, his notion of natural selection, evolution, and so did its independent discoverer, Alfred Wallace, from reading Malthus.
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.
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