Evolution of the foreskin: Difference between revisions

 
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[[Image:Charles-Darwin.jpg|right|thumb|Charles Darwin.]]
[[Image:Charles-Darwin.jpg|right|thumb|Charles Darwin.]]


Millions of years of evolution have fashioned the human body into a model of refinement, elegance, and efficiency, with every part having a function and purpose. Evolution has determined that mammals' genitals should be sheathed in a protective, responsive, multipurpose [[foreskin]]. Every normal human being is born with a [[foreskin]]. In females, it protects the glans of the [[clitoris]]; in males, it protects the [[glans]] of the [[penis]]. Thus, the foreskin is an essential part of human sexual anatomy.<ref>{{REFjournal
Millions of years of evolution have fashioned the human body into a model of refinement, elegance, and efficiency, with every part having a function and purpose. Evolution has determined that mammals' genitals should be sheathed in a [[Immunological and protective function of the foreskin| protective]], responsive, multipurpose [[foreskin]]. Every normal human being is born with a [[foreskin]]. In females, it protects the glans of the [[clitoris]]; in males, it protects the [[glans]] of the [[penis]]. Thus, the foreskin is an essential part of human sexual anatomy.<ref>{{REFjournal
  |last=Fleiss
  |last=Fleiss
  |first=Paul M.
  |first=Paul M.
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  |title=The Case Against Circumcision
  |title=The Case Against Circumcision
  |journal=Mothering: The Magazine of Natural Family Living
  |journal=Mothering: The Magazine of Natural Family Living
|season=Winter
  |volume=
  |volume=
  |issue=
  |issue=
  |pages=36-45
  |pages=36-45
  |url=http://www.mothersagainstcirc.org/fleiss.html
  |url=https://www.cirp.org/news/1997/1997-12-01_Mothering.php
  |quote=
  |quote=
|pubmedID=
 
|pubmedCID=
|DOI=
  |date=1997
  |date=1997
  |accessdate=
  |accessdate=2024-12-22
}}</ref>
}}</ref>


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== Evolution ==
== Evolution ==
===Natural selection===
===Natural selection===
Charles Darwin (1859) has done an admirable work in introducing the principle of ''natural selection'' to explain evolution.<ref>{{REFbook
[[Charles Darwin]] (1859) has done an admirable work in introducing the principle of ''natural selection'' to explain evolution.<ref>{{REFbook
  |last=Darwin
  |last=Darwin
  |first=Charles
  |first=Charles
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  |year=1859
  |year=1859
  |title=The Origin of Species
  |title=The Origin of Species
  |chapter=Four: Natural Selection
  |chapter=[https://www.gutenberg.org/files/1228/1228-h/1228-h.htm#chap04 Chapter Four: Natural Selection]
  |url=
  |url=
  |scope=
  |scope=
  |location=
  |location=London
  |publisher=
  |publisher=John Murray
  |ISBN=
  |ISBN=
  |accessdate=2024-12-18
  |accessdate=2024-12-18
  }}</ref>
  }}</ref>
=== Morphology ===
=== Morphology ===
The [[prepuce]] has been well conserved by evolution.<ref name="cold-mcgrath"/> In primates, the [[foreskin]] has been present in the genitalia of both sexes of mammals for at least 65 million years and likely has been present for over 100 millions years of evolution, based on its commonality as an anatomical feature in mammals.<ref>{{REFbook
The [[prepuce]] has been well conserved by evolution.<ref name="cold-mcgrath"/> In primates, the [[foreskin]] has been present in the genitalia of both sexes of mammals for at least 65 million years and likely has been present for over 100 million years of evolution, based on its commonality as an anatomical feature in mammals.<ref>{{REFbook
  |last=Martin
  |last=Martin
  |first=Robert D.
  |first=Robert D.
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  |year=1871
  |year=1871
  |title=The Descent of Man and Selection in Relation to Sex
  |title=The Descent of Man and Selection in Relation to Sex
  |url=
  |url=https://darwin-online.org.uk/converted/published/1874_Descent_F944/1874_Descent_F944.html
  |editor=
  |editor=
  |edition=
  |edition=
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  |isbn=1148750932
  |isbn=1148750932
  |quote=
  |quote=
  |accessdate=
  |accessdate=2024-12-22
  |note=
  |note=
}}</ref><ref>{{REFbook
}}</ref><ref name="short1981">{{REFbook
  |last=Short
  |last=Short
  |init=RV
  |init=RV
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  |accessdate=
  |accessdate=
  |note=
  |note=
}}</ref> It has been proposed that the foreskin evolved to facilitate [[masturbation]].<ref>{{REFjournal
}}</ref> It has been proposed that the [[foreskin]] evolved to facilitate [[masturbation]],<ref name="cox1995">{{REFjournal
  |last=Cox
  |last=Cox
  |first=Guy
  |first=Guy
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  |issue=6
  |issue=6
  |pages=617-621
  |pages=617-621
  |url=
  |url=https://www.sciencedirect.com/science/article/abs/pii/0306987795902481
  |quote=
  |quote=
  |pubmedID=8771059
  |pubmedID=8771059
  |pubmedCID=
  |pubmedCID=
  |DOI=
  |DOI=10.1016/0306-9877(95)90248-1
  |date=1995
  |date=1995
  |accessdate=
  |accessdate=2024-12-22
}}</ref> The human prepuce has an increase in corpuscular innervation and concomitant decrease in corpuscular receptors in the human [[glans]] compared to the prepuce and glans of lower primates, demonstrating an evolutionary advancement.<ref>{{REFjournal
}}</ref> but, in accordance with Darwin's principles of survival, it is more likely that the [[gliding action]] of the male prepuce facilitates penetration and fertilization of the female.<ref>{{REFjournal
|last=Taves
|first=
|init=DR
|author-link=
|etal=no
|title=The intromission function of the foreskin
|trans-title=
|journal=Medical Hypotheses
|location=
|date=2002-08
|volume=59
|issue=2
|pages=180-2
|url=https://www.cirp.org/library/anatomy/taves1/10
|archived=
|quote=
|pubmedID=12208206
|pubmedCID=
|DOI=10.1016/s0306-9877(02)00250-5
|accessdate=2024-12-22
}}</ref> The human prepuce has an increase in corpuscular innervation and concomitant decrease in corpuscular receptors in the human [[glans]] compared to the prepuce and glans of lower primates, demonstrating an evolutionary advancement.<ref name="nadler1995">{{REFjournal
  |last=Nadler
  |last=Nadler
  |first=Ronald D.
  |first=Ronald D.
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  |issue=2
  |issue=2
  |pages=93-102
  |pages=93-102
  |url=
  |url=https://onlinelibrary.wiley.com/doi/10.1002/ajp.1350370204
  |quote=
  |quote=
  |pubmedID=
  |pubmedID=31936943
  |pubmedCID=
  |pubmedCID=
  |DOI=10.1002/ajp.1350370204
  |DOI=10.1002/ajp.1350370204
  |date=1995
  |date=1995
  |accessdate=
  |accessdate=2024-12-22
}}</ref><ref>{{REFjournal
}}</ref><ref>{{REFjournal
  |last=Williams-Ashman
  |last=Williams-Ashman
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  |issue=
  |issue=
  |pages=335-374
  |pages=335-374
  |url=
  |url=https://muse.jhu.edu/article/402394
  |quote=
  |quote=
  |pubmedID=2188210
  |pubmedID=2188210
  |pubmedCID=
  |pubmedCID=
  |DOI=
  |DOI=10.1353/pbm.1990.0008
  |date=1990
  |date=1990
  |accessdate=
  |accessdate=2024-12-22
}}</ref> The human penis has retained and modified its prepuce over a period of extraordinarily evolution.<ref>{{REFjournal
}}</ref> The human [[penis]] has retained and modified its prepuce over an extraordinary period of evolution.<ref>{{REFjournal
  |last=Dixson
  |last=Dixson
  |init=AF
  |init=AF
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  |issue=1
  |issue=1
  |pages=51-60
  |pages=51-60
  |url=
  |url=https://onlinelibrary.wiley.com/doi/10.1002/ajp.1350130107
  |quote=
  |quote=
  |pubmedID=
  |pubmedID=2188210
  |pubmedCID=
  |pubmedCID=
  |DOI=10.1002/ajp.1350130107
  |DOI=10.1002/ajp.1350130107
  |date=1987
  |date=1987
  |accessdate=2010-06-22
  |accessdate=2024-12-22
}}</ref> The rapid divergence in external genital anatomy between humans and ancestral apes is thought to have occurred in the last seven million years.<ref name="cold-mcgrath"/>
}}</ref> The rapid divergence in external genital anatomy between humans and ancestral apes is thought to have occurred in the last seven million years.<ref name="cold-mcgrath"/>


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[[Image:Rhesus-Monkey-&-Human-Penis.gif]]
[[Image:Rhesus-Monkey-&-Human-Penis.gif]]


The rhesus monkey has fewer corpuscular receptors in the prepuce (foreskin) and more corpuscular receptors in the glans (head). In humans, however, the [[glans penis]] has few corpuscular receptors and predominant free nerve endings,<ref>Halata, Z, & Spaethe, A. (1997). Sensory innervation of the human penis. Plenum Press.</ref><ref name="halta86">Halata, Z, & Munger, B. (1986). The neuroanatomical basis for the protopathic sensibility of the human glans penis. Brain Res, 34(506)</ref> consistent with protopathic sensibility. Protopathic simply refers to a low order of sensibility (consciousness of sensation), such as to deep pressure and pain, that is poorly localised. The human glans penis has virtually no fine touch sensation and can only sense deep pressure and pain at a high threshold.<ref>Von, F.M. (1894). Beiträge zur Physiologie des Schmerzsinns. Akad Wiss Leipzig Math.-Naturwiss Kl Ber.</ref><ref name="macaca"/> While the human [[glans penis]] is protopathic, the [[prepuce]] contains a high concentration of touch receptors in the [[Ridged band|ridged band]].<ref name="cold-mcgrath"/>
The rhesus monkey has fewer corpuscular receptors in the prepuce (foreskin) and more corpuscular receptors in the glans (head). In humans, however, the [[glans penis]] has few corpuscular receptors and predominant free nerve endings,<ref name="halata1997">{{REFjournal
|last=Halata
|first=
|init=Z
|author-link=
|last2=Spaethe
|first2=
|init2=A
|author2-link=
|etal=no
|title=Sensory Innervation of the Human Penis
|trans-title=
|language=
|journal=Adv Exp Med Biol
|location=
|date=1997
|season=
|volume=424
|issue=
|article=
|page=
|pages=
|url=https://cirp.org/library/anatomy/halata2/
|archived=
|quote=
|pubmedID=9361804
|pubmedCID=
|DOI=10.1007/978-1-4615-5913-9_48
|accessdate=2024-12-22
}}</ref>


In the human [[penis]], the [[prepuce]] is known to have ten times more corpuscular sensory receptors than the [[glans penis]].<ref name="halta86"/>
In the human [[penis]], the [[prepuce]] is known to have ten times more corpuscular sensory receptors than the [[glans penis]].<ref name="halata1986">{{REFjournal
|last=Halata
|first=
|init=Z
|author-link=
|last2=Munger
|first2=
|init2=BL
|author2-link=
|etal=no
|title=The neuroanatomical basis for the protopathic sensibility of the human glans penis
|trans-title=
|language=
|journal=Brain Res
|date=1986-04-23
|volume=371
|issue=2
|pages=205-30
|url=
|archived=
|quote=
|pubmedID=3697758
|pubmedCID=
|DOI=10.1016/0006-8993(86)90357-4
|accessdate=2024-12-22
}}</ref>


The male and female prepuce has persisted in all primates, which strongly supports the contention that the [[prepuce]] is valuable genital sensory tissue. The corpora cavernosa and the prepuce are the only two universally common characteristics of the primate penis.<ref name="cold-mcgrath"/>
The male and female prepuce has persisted in all primates, which strongly supports the contention that the [[prepuce]] is valuable genital sensory tissue. The corpora cavernosa and the prepuce are the only two universally common characteristics of the primate penis.<ref name="cold-mcgrath"/><ref name="macaca"/> While the human [[glans penis]] is protopathic, the [[prepuce]] contains a high concentration of touch receptors in the [[Ridged band|ridged band]].<ref name="cold-mcgrath"/>


=== Further reading ===
== Further reading ==
* {{REFbook
* {{REFbook
  |last=Denniston
  |last=Denniston
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}}
}}


[[Image:The-Descent-of-Man-and-Selection-in-Relation-to-sex.gif|100x130px]]
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[[Image:Primate_Origins_and_Evolution.gif‎|100x130px]]
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[[Image:Perspectives_in_biology_and_medicine.gif‎|100x130px]]
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[[Image:America_Journal_of_Primatology.gif‎|100x130px]]
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[[Image:Why_Sex_Is_Fun.gif‎|100x130px]]
[[Image:Why_Sex_Is_Fun.gif‎|200x260px]]
[[Image:Mothering.gif‎|100x130px]]
[[Image:Mothering.gif‎|200x260px]]


=== Videos ===
== Videos ==
==== Functions of The Foreskin - Part 1 ====
=== Functions of The Foreskin - Part 1 ===
<youtube>http://www.youtube.com/watch?v=r9DoCn3gATE</youtube>
<youtube>http://www.youtube.com/watch?v=r9DoCn3gATE</youtube>


==== Functions of The Foreskin - Part 2 ====
=== Functions of The Foreskin - Part 2 ===
<youtube>http://www.youtube.com/watch?v=Ps1dkbcOKfA</youtube>
<youtube>http://www.youtube.com/watch?v=Ps1dkbcOKfA</youtube>
{{SEEALSO}}
{{SEEALSO}}
* [[Foreskin sensitivity]]
* [[Foreskin sensitivity]]
* [[Penis]]
* [[Penis]]
{{LINKS}}
{{LINKS}}
* * {{REFweb
* {{REFweb
  |url=http://www.intactaus.org/information/functionsoftheforeskin/
  |url=https://intactaus.org/information/functions-of-the-foreskin/
  |title=Functions of the Foreskin
  |title=Functions of the Foreskin
  |last=Helard
  |last=Helard
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  |quote=
  |quote=
}}
}}
{{REF}}
{{REF}}