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Darwin is not based on sexual attraction
Darwin based his idea of evolution on sex
Quote from: another_someone on 11/03/2008 12:16:27Darwin based his idea of evolution on sex That is totally inaccurate - it is only those who, because of subtle advantageous characteristics, survive to produce. Please don't quibble when you make a blanket statement such as this. Darwin was not on about sex in any way shape or form. It was about natural selection. There is a vast difference.
Darwin used comparison to selective breeding and artificial selection as a means for understanding natural selection. No such connection between selective breeding and natural selection was made by Wallace; he expressed it simply as a basic process of nature and did not think the phenomena were in any way related. On Wallace's own first edition of The Origin of Species, he crossed out every instance of the phrase "natural selection" and replaced with it Spencer's "survival of the fittest."
If we are talking about how Darwin originally framed his theory, it is. Artificial selection or selective breeding has nothing to do with sexual attraction. Your quote is about selective breeding and the dispute over natural selection and survival of the fittest. What on God's green earth does this have to do with sexual attraction? Sexual attraction as a means of selection was not even introduced into the thought process until the almost the 20th century!
'Best able to find food', 'best able to avoid being eaten', best able to deal with climate change' AND 'best able to reproduce' are all examples of 'fitness'.If a peacock can get his end away more often by having a big sexy tail then it is a 'fitness' criterion.Whether or not Darwin included it as an example in his theory is hardly very relevant, is it?
Darwin based his idea of evolution on sex (i.e. he suggested that evolution went about because males and females selected sexual partners that were beneficial to their children, either through deliberate choice, or because those without the beneficial traits simply did not survive).
Quote from: another_someone on 11/03/2008 12:16:27Darwin based his idea of evolution on sex (i.e. he suggested that evolution went about because males and females selected sexual partners that were beneficial to their children, either through deliberate choice, or because those without the beneficial traits simply did not survive)."males and females selected sexual partners"- from aboveWalks like a duck, squawks like a duck, looks like a duck.
survival of the fittest or theory of natural selection
Sexual selection is the theory proposed by Charles Darwin that states that the frequency of traits can increase or decrease depending on the attractiveness of the bearer.The theory of sexual selection was first proposed by Charles Darwin in his book The Origin of Species, though it was primarily devoted to natural selection. A later work, The Descent of Man and Selection in Relation to Sex dealt with the subject of sexual selection exhaustively, in part because Darwin felt that natural selection alone was unable to account for certain types of apparently non-competitive adaptations, such as the tail of a male peacock. He once wrote to a colleague that "The sight of a feather in a peacock's tail, whenever I gaze at it, makes me sick!" His work divided sexual selection into two primary categories: male-male competition (which would produce adaptations such as a Bighorn Sheep's horns, which are used primarily in sparring with other males over females), and cases of female choice (which would produce adaptations like beautiful plumage, elaborate songs, and other things related to impressing and attracting).Darwin's views on sexual selection were opposed strongly by his "co-discoverer" of natural selection, Alfred Russel Wallace, though much of his "debate" with Darwin took place after Darwin's death. Wallace argued that the aspects of it which were male-male competition, while real, were simply forms of natural selection, and that the notion of "female choice" was attributing the ability to judge standards of beauty to animals far too cognitively undeveloped to be capable of aesthetic feeling (such as beetles). Historians have noted that Wallace had previously had his own problem with "female choice": he had been left at the altar by a woman of a higher social class.Wallace also argued that Darwin too much favored the bright colors of the male peacock as adaptive without realizing that the "drab" peahen's coloration is itself adaptive, as camouflage. Wallace more speculatively argued that the bright colors and long tails of the peacock were not adaptive in any way, and that bright coloration could result from non-adaptive physiological development (for example, the internal organs of animals, not being subject to a visual form of natural selection, come in a wide variety of bright colors). This has been questioned by later scholars as quite a stretch for Wallace, who in this particular instance abandoned his normally strict "adaptationist" agenda in asserting that the highly intricate and developed forms such as a peacock's tail resulted by sheer "physiological processes" that were somehow not at all subjected to adaptation.Though Darwin considered sexual and natural selection to be two separate processes of equal importance, most of his contemporaries were not convinced, and sexual selection is usually de-emphasized as being a lesser force than, or simply a part of, natural selection.The sciences of evolutionary psychology, human behavioral ecology, and sociobiology study the influence of sexual selection in humans, though these are often controversial fields. The field of epigenetics is broadly concerned with the competence of adult organisms within a given sexual, social, and ecological niche, which includes the development of mating competences, e.g., by mimicking adult behavior.
The difference is whether one is looking at fitness within the context of an external environment, or fitness with regard to an environment that is itself generated by the species itself, rather than external to the species.
QuoteThe difference is whether one is looking at fitness within the context of an external environment, or fitness with regard to an environment that is itself generated by the species itself, rather than external to the species.Why do you draw a distinction?As far as the 'selfish gene' is concerned it just needs the best chance of success. Both male and female are 'fitter' if she has the sense to choose a 'fit' male. In this case, 'fitness' represents the ability to produce a fancy display and to be capable of surviving and the ability to recognise that as a way of promoting the female genes.Good old Richard Dawkins makes this point and I agree with him. (He must be very pleased about that.)
Referring to the original question (always worth while, occasionally) all that is necessary is to to contrast the idea of Lamarck's idea of passing on some 'learned' characteristic directly to the next generation and the Darwinian idea that effectiveness in survival and reproduction governs the success or failure of some characteristic to turn up in future generations.Trying to decide exactly what Darwin did or did not think or what he meant by what he wrote is not part of the original brief. And who can tell, in any case?BTW, Is there any actual evidence to support the Lamarck view, these days?
And, as for Linnaeus, his classification system hangs almost entirely on visible structure. Nowadays there is a possibly 'better' way, based on DNA comparisons. A number of species now find themselves in a very different place in their family tree.
Darwin's Origin of Species proposed natural selection as the main mechanism for development of species, but did not rule out a variant of Lamarckism as a supplementary mechanism.
Quote from: sophiecentaur on 11/03/2008 23:05:48BTW, Is there any actual evidence to support the Lamarck view, these days?No
BTW, Is there any actual evidence to support the Lamarck view, these days?