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Sexual selection modern humans

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In the Light of Evolution: Two Centuries of Darwin. National Academies Press US ; Charles Darwin laid the foundation for all modern work on sexual selection in his seminal book The Descent of Man, and Selection in Relation Sexual selection modern humans Sex.

In this work, Darwin fleshed out the mechanism of sexual selection, a hypothesis that he had proposed in The Origin of Species. He went well beyond a simple description of the phenomenon by providing extensive evidence and considering the far-reaching implications of the idea. Here we consider the contributions of Darwin to sexual selection with a particular eye on how far we have progressed in the last years.

We focus on 2 key questions in sexual selection. First, why does mate choice evolve at all?

Sexual selection in humans concerns...

And second, what factors determine the strength of mate choice or intensity of sexual selection in each sex? Darwin provided partial answers to these questions, and the progress that has been made on both of these topics since his time should be seen as one of the great triumphs of modern evolutionary biology.

However, a review of the literature shows that key aspects of sexual selection are still plagued by confusion and disagreement.

Many of these areas are complex and will require new theory and empirical Sexual selection modern humans for complete resolution.

Although we have made significant progress in some areas of sexual selection research, we still have much to accomplish.

C harles Darwin proposed the concept of sexual selection years ago in On the Origin of Species by Means of Natural Selection Darwin,but his definitive work Sexual selection modern humans sexual selection was undoubtedly The Descent of Man, and Selection in Relation to SexSexual selection modern humans was published in In typical Darwinian fashion, The Descent of Man, and Selection in Relation to Sex is a colossal tome with a tongue-tripping title that we will henceforth abbreviate as The Descent of Man that strolls through myriad topics relevant to evolutionary biology and ecology.

Consequently, it is futile to attempt to characterize the full spectrum of topics addressed in this book, which touched upon such sundry issues as species concepts, taxonomy, correlated evolution, sex-limited inheritance, and group selection, to name a few.

Rather, we focus on the contributions of Darwin in light of modern research in sexual selection, and in so doing we identify a few important topics for which a thread of reasoning can be traced from Darwin to the present.

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One of the great strengths of Darwin was that he often constructed his literary works with a clear argument in mind and marshaled vast amounts of Sexual selection modern humans to support his case.

Darwin believed that sexual selection played a major role in the evolution of humans and the divergence among distinct human populations, so he felt a lengthy description of sexual selection was necessary.

It is difficult to find a quote from Darwin that captures the full essence of his concept of sexual selection, but he provides the following definition:. We Sexual selection modern humans, however, here concerned only with that kind of selection, which I have called sexual selection. This depends on the advantage which certain individuals have over other individuals of the same sex and species, in exclusive relation to reproduction.

However, Darwin makes it clear that not all selection related to reproduction constitutes sexual selection, as primary sexual traits—like ovaries and testes—can evolve as a consequence of natural selection. Aside from the definition of sexual selection, what did Darwin accomplish in The Descent of Man? Here we try to focus on those parts of the book that are still relevant to modern research, and from our perspective Darwin identified 2 major themes that set the stage for work on sexual selection.

The first theme concerned the question of why sexual selection occurs in the first place. The second theme is related to the question of why sexual selection is strong in some lineages but not others. This question continues to be a major theme of modern research, but Darwin expressed Sexual selection modern humans amazingly modern, intuitive understanding of some of the explanations for the patterns of sexual selection among diverse evolutionary lineages Darwin, Rather than review all of the relevant literature, which for many of these topics has been done recently, we try to paint the current state of sexual selection with broad strokes.

Like Darwinwe focus on precopulatory sexual selection, leaving the treatment of postcopulatory processes for a different chapter in this volume Eberhard, Chapter Our sojourn through sexual selection literature leads to the identification of at least 2 major triumphs of precopulatory sexual selection research since Darwin. It also identifies numerous areas ripe for additional work. His original definition of sexual selection, which appeared in The Origin of Speciesappears to emphasize male-male combat [i.

Thus, Darwin identified the 2 main categories of sexual selection that persist to this day. Sexual selection would be relatively simple if there were nothing but what we call intrasexual selection.

In some species, males engage in fierce struggles among one another, and the victors in these contests tend to mate with the receptive females. Darwin provided numerous examples of species in which intrasexual combat for access to mates prevailed, some of the more interesting of which Sexual selection modern humans male narwhals fencing with their tusks [which remains to be studied, but see Gerson and Hickie ], male scarab beetles family Scarabaeidae battling with their elaborate horns Emlen et al.

However, intrasexual selection is not a sufficient mechanism by which to explain all of the diversity wrought by sexual selection.

Modern work shows that intersexual selection is a major aspect of sexual selection, a point that was deeply appreciated by Darwin. The female could in most cases escape, if wooed by a male that did not please or excite her; and when pursued, as so incessantly occurs, by several males, she would often have the opportunity, whilst they were Sexual selection modern humans together, of escaping with, or at least Sexual selection modern humans pairing with, some one male.

If the number of words devoted to each topic can serve as a guide, then Darwin felt that the Sexual selection modern humans of female choice required much more explanation than did male-male combat.

Here we will treat female choice, while keeping in mind that Darwin "Sexual selection modern humans" that in some systems mirror-image processes could occur through male choice. Sexual selection as a consequence of female choice is easy to understand, provided we are willing to accept that female preferences exist. If females show a preference, then males with the preferred trait will leave greater numbers of offspring, and their trait values will tend to increase in frequency in the population.

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