- Sexual selection in human evolution
Charles Darwininitially proposed his theory on sexual selection, there was considerable scepticism on its application to human evolution. More recently, the role of sexual selection in human evolution has begun to gain wide acceptance.
Charles Darwin conjectured that the male beard, as well as the relative hairlessness of humans compared to nearly all other mammals, are results of sexual selection. He reasoned that since, compared to males, the bodies of females are more nearly hairless, hairlessness is one of the atypical cases due to its selection by males at a remote prehistoric time, when males had overwhelming selective power, and that it nonetheless affected males due to genetic correlation between the sexes. He also hypothesized that sexual selection could also be what had differentiated between different human races, as he did not believe that natural selection provided a satisfactory answer.
Geoffrey Miller, drawing on some of Darwin's largely neglected ideas about human behavior, has hypothesized that
human culturearose through a process of sexual selection. He argues that cultural traits such as art, music, dance, verbal creativity and humor are of no survival value. Miller is critical of theories that imply that human culture arose as accidents or byproducts of human evolution. He believes that human culture arose through sexual selection for creative traits. In that view, many human artefacts could be considered subject to sexual selection as part of the extended phenotype, for instance clothing that enhance sexually selected traits.
Richard Dawkinspointed out in 1989 that the loss of the penis bone in humans, when it is present in our nearest related species the chimpanzee, demands some form of evolutionary explanation. He speculates that its loss is probably a form of sexual selection by females looking for signs of good health in prospective mates. The reliance of the human penis solely on hydraulicmeans to achieve a rigid state makes it particularly vulnerable to blood pressure variation. Poor erectile function betrays, not only physical states such as diabetes and neurological disorders, but mental states such as stress and depression. [cite book |last=Dawkins |first=Richard |authorlink=Richard Dawkins |coauthors= |editor= |others= |title=The Selfish Gene |origdate= |origyear=1978 |origmonth= |url= |format= |accessdate= |accessyear=2006 |accessmonth= |edition=30th anniversary edition |series= |date=2006 |year= |month= |publisher= |location=Endnote to 30th anniversary edition |language= |isbn= |oclc= |doi= |id= |pages=p158 endnote |chapter= |chapterurl= |quote= “It is not implausible that , with natural selection refining their diagnostic skills, females could glean all sorts of clues about a male’s health, and robustness of his ability to cope with stress, from the tone and bearing of his penis.” ]
During human evolution, on at least two occasions, hominid brain size increased rapidly over a relatively short period of time followed by a period of stasis. The first period of brain expansion occurred 2.5 million years ago, when homo habilis first began using stone tools. The second period occurred 500,000 years ago, with the emergence of
archaic homo sapiens. Miller argues that the rapid increases in brain size would have occurred by a positive feedback loop resulting in runaway selection for larger brains.
The human brain is thought to be a sexually selected trait, because it does not confer enough fitness in itself relative to its high maintenance costs (a quarter to a fifth of the energy and oxygen consumed by a human). [ [http://www.plosone.org/article/fetchArticle.action?articleURI=info:doi/10.1371/journal.pone.0000062 PLoS ONE: Sexual Selection and the Evolution of Brain Size in Primates ] ] Though the human brain does not confer any fitness benefits in itself, it may however have been an indicator of fitness. This in the same way that peacocks tail itself is not has no fitness value, but the quality of the tail is an indicator of the overall health of the peacock.
Sex differences in humans
Runaway sexual selection
The Mating Mind By Geoffrey F. Miller Published by Anchor Books, 2001 ISBN 038549517X, 9780385495172
Wikimedia Foundation. 2010.
Look at other dictionaries:
Sexual selection — This article is about the evolutionary concept. For the selection of the sex of offspring, see sex selection. Goldie s Bird of paradise: Ornamented male above; female below. Paradesia decora by John Gerrard Keulemans (d.1912) Sexual selection, a… … Wikipedia
Human evolution — This article is about the divergence of Homo sapiens from other species. For a complete timeline of human evolution, see Timeline of human evolution. Reconstruction of Homo heidelbergensis which may be the direct ancestor of both Homo… … Wikipedia
human evolution — Evolution of modern human beings from nonhuman and extinct hominid forms. Genetic evidence points to an evolutionary divergence between the lineages of humans and the great apes (Pongidae) on the African continent 5–8 million years ago. The… … Universalium
Major Histocompatibility Complex and Sexual Selection — A pathogen is any agent that causes disease. The body has two defense mechanisms for dealing with pathogenic microorganisms and other harmful substances: the inflammatory reaction and the development of an acquired immunity. Acquired immunity… … Wikipedia
Human penis size — is the measured length and width of the human penis. The most accurate measurement of the human penis comes from several measurements at different times, as there is natural variability in size due to arousal level, time of day, room temperature … Wikipedia
evolution — evolutional, adj. evolutionally, adv. /ev euh looh sheuhn/ or, esp. Brit., /ee veuh /, n. 1. any process of formation or growth; development: the evolution of a language; the evolution of the airplane. 2. a product of such development; something… … Universalium
Sexual dimorphism in non-human primates — has long been observed in the primate family, with numerous studies performed to document and explain the phenomenon. Recent studies have mainly used the technique of comparative analysis to examine both the variation in the expression of the… … Wikipedia
Human genetic variation — is the natural variation in gene frequencies observed between the genomes of individuals or groups of humans. Variation can be measured at both the individual level (differences between individual people) and at the population level, i.e.… … Wikipedia
Selection sexuelle — Sélection sexuelle Les mécanismes de l évolution biologique Mécanismes non aléatoires: sélection naturelle sélection utilitaire sélection sexuelle sélection de parentèle sélection de groupe sé … Wikipédia en Français
Evolution — ist die Veränderung der vererbbaren Merkmale einer Population von Lebewesen von Generation zu Generation. Diese Merkmale sind in Form von Genen kodiert, die bei der Fortpflanzung kopiert und an den Nachwuchs weitergegeben werden. Durch Mutationen … Deutsch Wikipedia