Robert Brockway: Created page with "The '''baculum''' (also '''penis bone''', '''penile bone''', or '''''os penis''''', '''''os genitale''''' or '''''os priapi'''''MLA Dolle,..."

2020-06-13T15:05:14Z

Created page with "The '''baculum''' (also '''penis bone''', '''penile bone''', or '''''os penis''''', '''''os genitale'''''<ref name="EvansLahunta2013"/> or '''''os priapi'''''<ref>MLA Dolle,..."

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The '''baculum''' (also '''penis bone''', '''penile bone''', or '''''os penis''''', '''''os genitale'''''<ref name="EvansLahunta2013"/> or '''''os priapi'''''<ref>MLA
Dolle, P., et al. "[http://genesdev.cshlp.org/content/5/10/1767.full.pdf HOX-4 genes and the morphogenesis of mammalian genitalia]." Genes & Development 5.10 (1991): 1767–1776.</ref>) is a [[bone]] found in the [[penis]] of many [[placental mammal]]s. It is absent in the [[human penis]], but present in [[Penis#Primates|the penises of other primates]], such as the [[gorilla]] and [[chimpanzee]].<ref name="Dixson2012">{{cite book|author=Alan F. Dixson|title=Primate Sexuality: Comparative Studies of the Prosimians, Monkeys, Apes, and Humans|url=https://books.google.com/books?id=khzhd2nXWM0C&printsec=frontcover#v=onepage&q=baculum%20OR%20%22os%20penis%22&f=false|date=26 January 2012|publisher=OUP Oxford|isbn=978-0-19-150342-9}}</ref><ref name="patterns" /> The os penis arises from primordial cells within soft tissues of the penis, and its formation is largely under the influence of androgens.<ref>{{cite journal |last1=Nasoori |first1=Alireza |title=Formation, structure, and function of extra‐skeletal bones in mammals |journal=Biological Reviews |date=2020 |doi=10.1111/brv.12597 |url=https://onlinelibrary.wiley.com/doi/abs/10.1111/brv.12597}}</ref> The bone is located above the [[male urethra]],<ref name="PerrinWursig2009" /> and it aids [[sexual reproduction]] by maintaining sufficient stiffness during [[sexual penetration]]. The [[Homology (biology)|homologue]] to the baculum in [[female mammals]] is known as the baubellum or os clitoridis, a bone in the [[clitoris]].<ref>{{cite journal |last=Best |author2=Granai |date=2 December 1994 |title=Tamius merriami |journal=Mammalian Species |volume=476 |issue=476 |pages=1–9 |url=http://www.science.smith.edu/departments/Biology/VHAYSSEN/msi/pdf/i0076-3519-476-01-0001.pdf |doi=10.2307/3504203|jstor=3504203 }}</ref><ref>{{cite book |url= https://books.google.com/books?id=MFw4AAAAIAAJ&pg=PA264&lpg=PA264#v=onepage&q&f=false |title=Biological Actions of Sex Hormones |page=264 |author=Harold Burrows|publisher=Cambridge University Press|year=1945 |accessdate=4 August 2012|isbn=9780521043946 }}</ref><ref name="Ewer1973-2">{{cite book|author=R. F. Ewer|title=The Carnivores|url=https://books.google.com/books?id=IETMd3-lSlkC&printsec=frontcover#v=snippet&q=os+clitoridis&f=false|accessdate=16 December 2012|year=1973|publisher=Cornell University Press|isbn=978-0-8014-8493-3}}</ref>

Unlike most other primates, humans lack an os penis or os clitoris;<ref>{{Cite journal | doi=10.1002/ajpa.20734| pmid=18046752|title = The evolution of human reproduction: A primatological perspective| journal=American Journal of Physical Anthropology| volume=134| pages=59–84|year = 2007|last1 = Martin|first1 = Robert D.}}</ref><ref name="Ankel-Simons2010">{{cite book|author=Friderun Ankel-Simons|title=Primate Anatomy: An Introduction|url=https://books.google.com/books?id=Mwl3M6c5KzoC&printsec=frontcover&vq=pensi#v=onepage&q=baculum%20OR%20%22os%20penis%22&f=false|date=27 July 2010|publisher=Elsevier|isbn=978-0-08-046911-9}}</ref> however, this bone is present but much reduced among the [[great ape]]s. In many ape species, it is a relatively insignificant {{Convert|10|-|20|mm|abbr=on|adj=on}} structure. Cases of [[human penis]] ossification following trauma have been reported,<ref>{{cite journal |last=Sarma |first=Deba |author2=Thomas Weilbaecher |year=1990 |title=Human os penis |journal=Urology |volume=35 |issue= 4|pages=349–350 |doi=10.1016/0090-4295(90)80163-H |pmid=2108520 }}</ref> and one case was reported of a congenital os penis surgically removed from a 5-year-old boy, who also had other developmental abnormalities, including a [[Ambiguous genitalia|cleft scrotum]].<ref>{{cite journal |last=Champion |first=RH |author2=J Wegrzyn |year=1964 |title=Congenital os penis |journal=Journal of Urology |volume=91 |issue=6 |pages=663–4 |pmid=14172255 |doi=10.1016/S0022-5347(17)64197-1 }}</ref> [[Clellan S. Ford]] and [[Frank A. Beach]] in ''[[Patterns of Sexual Behavior]]'' (1951), p. 30 say, "Both gorillas and chimpanzees possess a penile bone. In the latter species, the os penis is located in the lower part of the organ and measures approximately three-quarters of an inch in length."<ref name="patterns">''Patterns of Sexual Behavior'' Clellan S. Ford and Frank A. Beach, published by Harper & Row, New York in 1951. {{ISBN|0-313-22355-6}}</ref> In humans, the rigidity of the [[erection]] is provided entirely through blood pressure in the [[corpus cavernosum penis|corpora cavernosa]]. An "artificial baculum" or [[penile implant]] is sometimes used to treat erectile dysfunction in humans.<ref>Carrion, Hernan, et al. "[http://www.jsm.jsexmed.org/article/S2050-0521(16)30006-3/fulltext A history of the penile implant to 1974]." Sexual medicine reviews 4.3 (2016): 285–293.</ref>

The loss of the bone in humans, when it is present in our nearest related species the chimpanzee, is thought to be because humans "evolved a [[mating system]] in which the male tended to accompany a particular female all the time to try to ensure paternity of her children"<ref name="WWB">{{cite web|url=http://www.abc.net.au/beasts/evidence/prog1/page4_2.htm |title=Godinotia |year=2002 |work=Walking With Beasts |publisher=ABC – BBC |pages=Question: How do we know how Godinotia (the primate in program 1) mated? |accessdate=7 July 2015 |url-status=dead |archiveurl=https://web.archive.org/web/20140429220805/http://www.abc.net.au/beasts/evidence/prog1/page4_2.htm |archivedate=29 April 2014 }}</ref>{{Citation needed|reason=An Australian Broadcasting Company is not a legitimate source; frankly, these entire two paragraphs are unsubstantiated anecdotes|date=April 2020}} which allows for frequent matings of short duration. Observation suggests that primates with a baculum only infrequently encounter females, but engage in longer periods of [[animal sexual behavior|copulation]] that the baculum makes possible, thereby maximizing their chances of fathering the female's offspring. Human females exhibit [[concealed ovulation]] also known as hidden estrus, meaning it is almost impossible to tell when the female is fertile, so frequent matings would be necessary to ensure paternity.<ref name="WWB" /><ref>{{Cite news|url=https://www.independent.co.uk/life-style/health-and-families/health-news/penis-bone-humans-baculum-sex-doesnt-last-long-enough-ucl-why-a7473401.html|title=Scientists have answered one of the biggest questions people have about their penis|date=2016-12-14|newspaper=The Independent|language=en-GB|access-date=2016-12-15}}</ref>{{clarify|reason=what evolutionaty advantage does "ensuring paternity" [of individual males] bring to the species as a whole??|date=December 2019}}

It has been speculated that the loss of the bone in humans, when it is present in our nearest related species the [[chimpanzee]], is a result of [[sexual selection]] by females looking for [[Signalling theory|honest signals]] of good health in prospective mates{{Citation needed|reason=if there is going to be speculation, then at least a source is needed so it's not just some person's opinion, man|date=April 2020}}. The reliance of the human penis solely on [[hydraulic]] means to achieve a rigid state makes it particularly vulnerable to blood pressure variation{{Citation needed|date=April 2020}}. Poor erectile function portrays not only physical states such as age, [[diabetes]], and [[neurological disorders]], but also mental states such as [[stress (biological)|stress]] and [[depression (mood)|depression]].<ref>{{cite book |last=Dawkins |first=Richard |authorlink=Richard Dawkins |title=The Selfish Gene |edition=30th anniversary |year=2006 |publisher= Oxford University Press|location=Endnote to 30th anniversary edition |isbn=978-0-19-929114-4 |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.|page=158 endnote |origyear= 1978|title-link=The Selfish Gene }}</ref>{{Citation needed|reason=Dawkins is not an anatomist or anthropologist and the quote starts off as spectulatory|date=April 2020}}

A third view is that its loss in humans is an example of [[neoteny]] during human evolution; late-stage fetal chimpanzees lack a baculum.<ref name="Bednarik">{{Cite book | doi = 10.1007/978-1-4419-9353-3| title = The Human Condition| year = 2011| last1 = Bednarik | first1 = R. G. | isbn = 978-1-4419-9352-6}} (page 134), cited by:<br />
{{cite journal |last=Achrati |first=Ahmed |date=November 2014 |title=Neoteny, female hominin and cognitive evolution |journal= [[Rock Art Research]] |volume=31 |issue=1 |pages=232–238 }}<br />
"In humans, neoteny is manifested in the resemblance of many physiological features of a human to a late-stage foetal chimpanzee. These foetal characteristics include hair on the head, a globular skull, ear shape, vertical plane face, absence of penal bone (baculum) in foetal male chimpanzees, the vagina pointing forward in foetal ape, the presence of hymen in neonate ape, and the structure of the foot. 'These and many other features', Bednarik says, 'define the anatomical relationship between ape and man as the latter's neoteny'"</ref>

Baculum - Revision history

Robert Brockway: Created page with "The '''baculum''' (also '''penis bone''', '''penile bone''', or '''''os penis''''', '''''os genitale''''' or '''''os priapi'''''MLA Dolle,..."