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A Critical Review of Charles Darwin's The Descent of Man and Its Relevance for Modern Science

to put that evolution in context, i begin with the phrase sexual selection, which is used by darwin, as descent uses it, to address the two sides of the human condition, namely, the two processes that darwin understands to apply in the evolution of species. the first is the idea that in the course of evolution, species have become specialized for certain reproductive strategies, such as a male birds ability to woo a female with a dance or a male fish having a hard. in the absence of such criteria, natural selection would have a tough time sorting out the winners and losers. the second is what darwin called its component parts, or the modification of an organisms structure or behavior that allows it to perform some function. for example, the red beaks of the kingfisher are not a modification of the beak. rather, they are a modification of the redness of the beak. darwin or the kingfisher, as he writes in his description of how the kingfisher flies, has acquired a red bill to aid him in catching fish. however, as he makes clear, the or can refer to the redness of the beak or the kingfishers wings. this distinction between the kinds of variation, or the kinds of modifications that natural selection can act on, is central to darwin understanding of evolution.

Charles Darwin The Descent Of Man Essay

there are several reasons that darwin did not speak of sexual selection in the origin, and only began to do so in descent. for one thing, he had just published his brilliant study of barnacles, the vestiges of creation (1844), and was already making the case that natural selection, not sexual selection, was the critical principle of evolution. he had just begun work on the expression of the emotions in man and animals (1872-1876), and had begun to think of sexual selection as a significant force in the evolution of human beings. but darwin also recognized that sexual selection was not yet a significant source of variation and so, unlike in the vestiges where he had examined the physical structures of barnacles, he refrained from speaking of sexual selection until the later work. in the descent, darwin takes us on a tour of such structures, from the kingfishers beak to the peacocks tail, to show us that the similarity between the evolution of barnacles and fishes in terms of sexual selection is not accidental. but he also wants to prepare us for the future, as it were, by explaining how it is that sexual selection could be a source of variation. he writes:


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