Fisherian runaway: Difference between revisions

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'''Fisherian runaway''' is a hypothesized mechanism by which sexual selection can lead to exaggerated and sometimes even maladaptive ornamentation and may play a role in the evolution of [[beauty]]. There is evidence that entire species have become extinct due to runaway sexual selection. The name derives from the originator of the concept, Ronald Fisher, the 20th century British statistician, geneticist, eugenicist and racialist.
'''Fisherian runaway''' is a hypothesized mechanism by which sexual selection can lead to exaggerated and sometimes even maladaptive ornamentation and may play a role in the evolution of [[beauty]]. There is evidence that entire species have become extinct due to runaway sexual selection. The name derives from the originator of the concept, Ronald Fisher, the 20th century British statistician, geneticist, eugenicist and racialist.


=Mechanism=
== Mechanism ==
[[File:Peacock courting peahen.jpg|alt=|thumb|"The females may be dull looking, but they're very picky." A peacock courting a peahen]]
[[File:Peacock courting peahen.jpg|alt=|thumb|"The females may be dull looking, but they're very picky." A peacock courting a peahen]]
Fisherian runaway is a feedback loop occurring across many generations, in which the one sex becomes more choosy about a heritable trait for the simple reason that others find the trait attractive. Members of this sex are not necessarily consciously aware of other's preferences, rather mutations that lead to preferring traits preferred by others are favored by selection due to the offspring more likely exhibiting traits that are preferred by others. In response to the greater choosiness, the other sex enlarges, overcomplicates or beautifies that trait in efforts of becoming more attractive. The exponential nature of feedback loops exerts a strong selection pressure that can even overcome the selective pressure for survival itself and hence lead to extinction. Such feedback loops can be initiated by arbitrary aesthetic selection, but also when a trait is slightly correlated with fitness, or when a trait is similar in appearance to attractive or otherwise valuable objects or body parts.<ref>Fuller, R. C., Houle, D., & Travis, J. 2005. ''Sensory Bias as an Explanation for the Evolution of Mate Preferences.'' [[https://www.jstor.org/stable/10.1086/444443 Abstract]], p. 444</ref> For example, women's breasts may have evolved to mimic their buttocks because the latter was already a sexually attractive body part before humans developed upright posture, and then Fisherian runaway may have lead to breasts becoming increasingly larger and rounder.
Fisherian runaway is a feedback loop occurring across many generations, in which the one sex becomes more choosy about a heritable trait for the simple reason that others find the trait attractive. Members of this sex are not necessarily consciously aware of other's preferences, rather mutations that lead to preferring traits preferred by others are favored by selection due to the offspring more likely exhibiting traits that are preferred by others. In response to the greater choosiness, the other sex enlarges, overcomplicates or beautifies that trait in efforts of becoming more attractive. The exponential nature of feedback loops exerts a strong selection pressure that can even overcome the selective pressure for survival itself and hence lead to extinction. Such feedback loops can be initiated by arbitrary aesthetic selection, but also when a trait is slightly correlated with fitness, or when a trait is similar in appearance to attractive or otherwise valuable objects or body parts.<ref>Fuller, R. C., Houle, D., & Travis, J. 2005. ''Sensory Bias as an Explanation for the Evolution of Mate Preferences.'' [[https://www.jstor.org/stable/10.1086/444443 Abstract]], p. 444</ref> For example, women's breasts may have evolved to mimic their buttocks because the latter was already a sexually attractive body part before humans developed upright posture, and then Fisherian runaway may have lead to breasts becoming increasingly larger and rounder.
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Since females are [[Bateman's principle|more choosy]] in many species throughout the animal kingdom (including humans), the males tend to be more ornamented.
Since females are [[Bateman's principle|more choosy]] in many species throughout the animal kingdom (including humans), the males tend to be more ornamented.


=Peafowl=
== Peafowl ==
For example, in peafowls, the males evolved to have extremely large plumage, most likely due to persistent female preference for large plumage, strengthened by Fisherian runaway.  The preference the peahens have for large plumage caused the peacock's plumage to become absurdly large, hindering its mobility to evade predators, and also requiring a lot of energy to grow and maintain.
For example, in peafowls, the males evolved to have extremely large plumage, most likely due to persistent female preference for large plumage, strengthened by Fisherian runaway.  The preference the peahens have for large plumage caused the peacock's plumage to become absurdly large, hindering its mobility to evade predators, and also requiring a lot of energy to grow and maintain.


=Sabre Tooth Tigers=
== Sabre Tooth Tigers ==
It has been hypothesized that Fisherian runaway selection contributed to the demise of the Sabre-tooth Tiger, by which female Sabre-tooths preference for males with long fangs resulted in a Fisherian runaway occurring, which led to the tiger's teeth becoming so large they became a liability, hampering the beasts ability to feed itself, and most likely led to frequent infections from the brittle, comically large teeth breaking.
It has been hypothesized that Fisherian runaway selection contributed to the demise of the Sabre-tooth Tiger, by which female Sabre-tooths preference for males with long fangs resulted in a Fisherian runaway occurring, which led to the tiger's teeth becoming so large they became a liability, hampering the beasts ability to feed itself, and most likely led to frequent infections from the brittle, comically large teeth breaking.


=Irish Elk=
== Irish Elk ==
The Irish elk is known to have gone extinct from female selection giving way to Fisherian runaway.  The female Irish elk preferred male Irish elk with large horns.  Eventually this preference created a feedback loop that resulted in Irish elk eventually evolving to carry 3.6 meter wide horns, one meter longer than its height.  Energy requirements for Irish elk antler growth were 75% as large as the energy requirements for fat and protein deposition. The enormous amount of calcium required to grow the antlers resulted the calcium being depleted from most of the body causing a state like similar to osteoporosis.  The adaptive trait in Irish elk became [[maladaptive]] and the species died out.
The Irish elk is known to have gone extinct from female selection giving way to Fisherian runaway.  The female Irish elk preferred male Irish elk with large horns.  Eventually this preference created a feedback loop that resulted in Irish elk eventually evolving to carry 3.6 meter wide horns, one meter longer than its height.  Energy requirements for Irish elk antler growth were 75% as large as the energy requirements for fat and protein deposition. The enormous amount of calcium required to grow the antlers resulted the calcium being depleted from most of the body causing a state like similar to osteoporosis.  The adaptive trait in Irish elk became [[maladaptive]] and the species died out.


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</gallery>
</gallery>


=Humans=
== Humans ==
Even though human females are more choosy in accordance to [[Bateman's principle]], both sexes are ornamented, e.g. women have [[Boobs|permanently swollen breasts]] and an hour glass shaped body, men have a V-shaped upper body, more toned muscles, beards, very large penises compared to other great apes, and [[Category:Aesthetics|a host of other features]]. Both sexes have [[Hairline|clearly defined hair lines]] and very clear skin. None of these features serve a known biological purpose besides being good looking, so they're likely sexually selected, likely mostly by aesthetic selection common to most animals<ref>http://people.idsia.ch/~juergen/beauty.html</ref>, and possibly by feedback loops like Fisherian runaway, leading to exaggeration and strengthened sexual dimorphism.
Even though human females are more choosy in accordance to [[Bateman's principle]], both sexes are ornamented, e.g. women have [[Boobs|permanently swollen breasts]] and an hour glass shaped body, men have a V-shaped upper body, more toned muscles, beards, very large penises compared to other great apes, and [[Category:Aesthetics|a host of other features]]. Both sexes have [[Hairline|clearly defined hair lines]] and very clear skin. None of these features serve a known biological purpose besides being good looking, so they're likely sexually selected, likely mostly by aesthetic selection common to most animals<ref>http://people.idsia.ch/~juergen/beauty.html</ref>, and possibly by feedback loops like Fisherian runaway, leading to exaggeration and strengthened sexual dimorphism.


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Men's rights activist [[Warren Farrell]] warned of such a thing in 1993, in his book, [[The Myth of Male Power]], warning women that their preference for and [[cheerleaders|encouragement of]], "hunter-killer", "star quarterback", type men could cause the extinction of the human race with the arrival of nuclear technology.  He also claimed that since civilization and the industrial revolution [[dark triad]] traits have become [[maladaptive]], as the traits which foster a healthy society have switched from might-makes-right individual brutality, to [[nice guy|cooperation, intelligence, empathy]] etc.
Men's rights activist [[Warren Farrell]] warned of such a thing in 1993, in his book, [[The Myth of Male Power]], warning women that their preference for and [[cheerleaders|encouragement of]], "hunter-killer", "star quarterback", type men could cause the extinction of the human race with the arrival of nuclear technology.  He also claimed that since civilization and the industrial revolution [[dark triad]] traits have become [[maladaptive]], as the traits which foster a healthy society have switched from might-makes-right individual brutality, to [[nice guy|cooperation, intelligence, empathy]] etc.


=Sexy Son hypothesis=
== Sexy Son hypothesis ==


The sexy son hypotheses was also proposed by Fisher and is merely a [https://en.wikipedia.org/wiki/Corollary corollary] of Fisherian runaway regarding men's beauty. It simply states that the positive feedback loop makes men's beauty so attractive that women are willing to choose a beautiful male regardless of other considerations such as morality or ability to provide to provide, because the males' beauty—which is partly heritable—confers on their offspring a potential reproductive advantage. There is indeed [[Scientific_Blackpill#A_man.27s_physical_attractiveness_predicts_how_long_he_waits_before_a_woman_will_allow_sex|compelling evidence]] of this behavior. Of course men also more readily copulate with beautiful women, but men have less parental investment and hence do not need to care as much about such considerations. Further, women's ability to provide does not matter nearly as much as men's and women also largely lack this ability (at least they did before the invention of modern welfare states). Hence, women's behavior of disregarding the ability to provide merely at the benefit of better looking offspring has much more drastic implications.
The sexy son hypotheses was also proposed by Fisher and is merely a [https://en.wikipedia.org/wiki/Corollary corollary] of Fisherian runaway regarding men's beauty. It simply states that the positive feedback loop makes men's beauty so attractive that women are willing to choose a beautiful male regardless of other considerations such as morality or ability to provide to provide, because the males' beauty—which is partly heritable—confers on their offspring a potential reproductive advantage. There is indeed [[Scientific_Blackpill#A_man.27s_physical_attractiveness_predicts_how_long_he_waits_before_a_woman_will_allow_sex|compelling evidence]] of this behavior. Of course men also more readily copulate with beautiful women, but men have less parental investment and hence do not need to care as much about such considerations. Further, women's ability to provide does not matter nearly as much as men's and women also largely lack this ability (at least they did before the invention of modern welfare states). Hence, women's behavior of disregarding the ability to provide merely at the benefit of better looking offspring has much more drastic implications.


=See Also=
== See Also ==
*[[Chadification]]
*[[Chadification]]
*[[Zyzz]]
*[[Zyzz]]
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=References=
== References ==
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