Baculum: Difference between revisions
Jump to navigation
Jump to search
imported>OAbot m Open access bot: url-access updated in citation with #oabot. |
imported>Kwamikagami |
||
| Line 6: | Line 6: | ||
The '''baculum''' ({{plural form}}: '''bacula'''), also known as the '''penis bone''', '''penile bone''', '''''os penis''''', '''''os genitale''''',<ref name="EvansLahunta2013"/> or '''''os priapi''''',<ref>{{cite journal | first1= P. | last1= Dollé | first2= J.-C.= | last2= Izpistia-Belmonte| first3= J.M. | last3=Brown| first4= C. | last4=Tickle| first5= D. | last5= Duboule | url= | The '''baculum''' ({{plural form}}: '''bacula'''), also known as the '''penis bone''', '''penile bone''', '''''os penis''''', '''''os genitale''''',<ref name="EvansLahunta2013"/> or '''''os priapi''''',<ref>{{cite journal | first1= P. | last1= Dollé | first2= J.-C.= | last2= Izpistia-Belmonte| first3= J.M. | last3=Brown| first4= C. | last4=Tickle| first5= D. | last5= Duboule | url= | ||
http://genesdev.cshlp.org/content/5/10/1767.full.pdf |title=HOX-4 genes and the morphogenesis of mammalian genitalia| | http://genesdev.cshlp.org/content/5/10/1767.full.pdf |title=HOX-4 genes and the morphogenesis of mammalian genitalia| archive-url= https://web.archive.org/web/20180720204753/http://genesdev.cshlp.org/content/5/10/1767.full.pdf |archive-date=20 July 2018 |journal= [[Genes & Development]]| volume= 5| number= 10 | year= 1991| pages=1767–1776| doi= 10.1101/gad.5.10.1767 | pmid= 1680771 | s2cid= 6307427 }}</ref> is a [[bone]] in the [[penis]] of many [[placental mammal]]s. It is not present in humans, but is present in the penises of some [[primate]]s, such as the [[gorilla]] and the [[chimpanzee]].<ref name= "Dixson2012">{{cite book| first=Alan F. | last= Dixson|title=Primate Sexuality: Comparative Studies of the Prosimians, Monkeys, Apes, and Humans| url= https://books.google.com/books?id=khzhd2nXWM0C|date=26 January 2012|publisher=OUP Oxford|isbn=978-0-19-150342-9|access-date=13 February 2018|archive-date=31 December 2013|archive-url= https://web.archive.org/web/20131231131810/http://books.google.com/books?id=khzhd2nXWM0C&printsec=frontcover|url-status=live}}</ref><ref name= "patterns" /> The baculum arises from primordial cells in soft tissues of the penis, and its formation is largely influenced by [[androgen]]s.<ref>{{cite journal |last1= Nasoori| first1= Alireza |date= 2020 |title= Formation, structure, and function of extra-skeletal bones in mammals| url= https://archive.org/details/formation-structure-and-function-of-extra-skeletal-bones-in-mammals| journal= [[Biological Reviews]] |volume= 95| issue=4|pages=986–1019| doi= 10.1111/brv.12597|pmid=32338826|s2cid=216556342}}</ref> The bone lies above the [[male urethra|urethra]],<ref name="PerrinWursig2009" /> and it aids [[sexual reproduction]] by maintaining stiffness during [[sexual penetration]]. The [[Homology (biology)|homologue]] to the baculum in [[female mammals]] is the [[baubellum]] (''os clitoridis''), a bone in the [[clitoris]].<ref>{{cite journal |last1=Best | first1= Troy L.|first2= Nancy J. | last2=Granai |date=2 December 1994 |title=Tamius merriami |journal= Mammalian Species |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 |s2cid=253909941 |access-date=15 January 2010 |archive-date=23 June 2010 |archive-url= https://web.archive.org/web/20100623032214/http://www.science.smith.edu/departments/Biology/VHAYSSEN/msi/pdf/i0076-3519-476-01-0001.pdf |url-status=live }}</ref><ref>{{cite book |url=https://books.google.com/books?id=MFw4AAAAIAAJ&pg=PA264 |title=Biological Actions of Sex Hormones |page=264 |first=Harold | last= Burrows |publisher=Cambridge University Press |year=1945 |access-date=4 August 2012 |isbn= 978-0-521-04394-6 |archive-date=21 October 2021 |archive-url= https://web.archive.org/web/20211021202329/https://books.google.com/books?id=MFw4AAAAIAAJ&pg=PA264 |url-status=live }}</ref><ref name= "Ewer1973-2">{{cite book| first=R. F. | last= Ewer|title=The Carnivores |url= https://books.google.com/books?id=IETMd3-lSlkC|access-date=16 December 2012| year=1973| publisher= Cornell University Press|isbn=978-0-8014-8493-3|archive-date=28 May 2013| archive-url= https://web.archive.org/web/20130528110801/http://books.google.com/books?id=IETMd3-lSlkC&printsec=frontcover| url-status= live}}</ref> | ||
== Etymology == | == Etymology == | ||
| Line 12: | Line 12: | ||
== Function == | == Function == | ||
The baculum is used for copulation and varies in size and shape by [[species]]. Its evolution may be influenced by [[sexual selection]], and its characteristics are sometimes used to differentiate between similar species.<ref>{{cite journal | last=Ramm | first=Steven A. | title=Sexual Selection and Genital Evolution in Mammals: A Phylogenetic Analysis of Baculum Length | journal=The American Naturalist | publisher=University of Chicago Press | volume=169 | issue=3 | year=2007 | issn=0003-0147 | doi=10.1086/510688 | pages=360–369| pmid=17238128 | bibcode=2007ANat..169..360R }}</ref> A bone in the penis allows a male to mate for a long time with a female,<ref>{{Cite book |last=Naguib |first=Marc |url=https://books.google.com/books?id=KgTeDwAAQBAJ&pg=PA95 |title=Advances in the Study of Behavior |date=2020-04-19 |publisher=Academic Press |isbn=978-0-12-820726-0 |language=en}}</ref><ref>{{cite journal | last=Dixson | first=A. F. | title=Baculum length and copulatory behaviour in carnivores and pinnipeds (Grand Order Ferae) | journal=Journal of Zoology | publisher=Wiley | volume=235 | issue=1 | year=1995 | issn=0952-8369 | doi=10.1111/j.1469-7998.1995.tb05128.x | pages=67–76}}</ref><ref>{{cite journal | last1=Dixson | first1=Alan | last2=Pissinatti | first2=Alcides | last3=Anderson | first3=Matt | title=A positive relationship between baculum length and prolonged intromission patterns in mammals | journal=Acta Zoologica Sinica | volume=50 | date=2004-01-01 | issn=0001-7302 | pages=490–503 | url=https://www.researchgate.net/publication/264790174 }}</ref> which can be a distinct advantage in some [[mating system|mating strategies]].<ref>{{cite journal | last1=H. Ferguson | first1=Steven | last2=Larivière | first2=Serge | title=Are long penis bones an adaption to high latitude snowy environments? | journal=Oikos | publisher=Wiley | volume=105 | issue=2 | date=2004-03-22 | issn=0030-1299 | doi=10.1111/j.0030-1299.2004.13173.x | pages=255–267| bibcode=2004Oikos.105..255F }}</ref><ref name="WWB" /> The length of the baculum may be related to the duration of [[copulation (zoology)|copulation]] in some species.<ref>{{cite journal|doi=10.1111/j.1469-7998.1987.tb03718.x|title=Observations on the evolution of the genitalia and copulatory behaviour in male primates|date=1987|last1=Dixson|first1=A. F.|journal=Journal of Zoology|volume=213|issue=3|pages=423–443}}</ref><ref>{{cite journal|doi=10.1016/j.cub.2012.11.001|pmid=23257184|title=The baculum|journal=Current Biology|volume=22|issue=24|pages=R1032–R1033|year=2012|last1=Stockley|first1=Paula|doi-access=free|bibcode=2012CBio...22R1032S }}</ref> In carnivorans<ref>{{cite journal | doi=10.1098/rspb.2020.1883 | title=Postcopulatory sexual selection and the evolution of shape complexity in the carnivoran baculum | year=2020 | last1=Brassey | first1=Charlotte A. | last2=Behnsen | first2=Julia | last3=Gardiner | first3=James D. | journal=Proceedings of the Royal Society B: Biological Sciences | volume=287 | issue=1936 | pmid=33049172 | pmc=7657853 }}</ref> and primates, the length of the baculum appears to be influenced by [[Sexual selection in mammals#Postcopulatory mechanisms|postcopulatory sexual selection]].<ref>{{cite journal | last1=Brindle | first1=Matilda | last2=Opie | first2=Christopher | title=Postcopulatory sexual selection influences baculum evolution in primates and carnivores | journal=Proceedings of the Royal Society B: Biological Sciences | volume=283 | issue=1844 | date=2016-12-14 | issn=0962-8452 | pmid=27974519 | pmc=5204150 | doi=10.1098/rspb.2016.1736 | doi-access=free | | The baculum is used for copulation and varies in size and shape by [[species]]. Its evolution may be influenced by [[sexual selection]], and its characteristics are sometimes used to differentiate between similar species.<ref>{{cite journal | last=Ramm | first=Steven A. | title=Sexual Selection and Genital Evolution in Mammals: A Phylogenetic Analysis of Baculum Length | journal=The American Naturalist | publisher=University of Chicago Press | volume=169 | issue=3 | year=2007 | issn=0003-0147 | doi=10.1086/510688 | pages=360–369| pmid=17238128 | bibcode=2007ANat..169..360R }}</ref> A bone in the penis allows a male to mate for a long time with a female,<ref>{{Cite book |last=Naguib |first=Marc |url=https://books.google.com/books?id=KgTeDwAAQBAJ&pg=PA95 |title=Advances in the Study of Behavior |date=2020-04-19 |publisher=Academic Press |isbn=978-0-12-820726-0 |language=en}}</ref><ref>{{cite journal | last=Dixson | first=A. F. | title=Baculum length and copulatory behaviour in carnivores and pinnipeds (Grand Order Ferae) | journal=Journal of Zoology | publisher=Wiley | volume=235 | issue=1 | year=1995 | issn=0952-8369 | doi=10.1111/j.1469-7998.1995.tb05128.x | pages=67–76}}</ref><ref>{{cite journal | last1=Dixson | first1=Alan | last2=Pissinatti | first2=Alcides | last3=Anderson | first3=Matt | title=A positive relationship between baculum length and prolonged intromission patterns in mammals | journal=Acta Zoologica Sinica | volume=50 | date=2004-01-01 | issn=0001-7302 | pages=490–503 | url=https://www.researchgate.net/publication/264790174 }}</ref> which can be a distinct advantage in some [[mating system|mating strategies]].<ref>{{cite journal | last1=H. Ferguson | first1=Steven | last2=Larivière | first2=Serge | title=Are long penis bones an adaption to high latitude snowy environments? | journal=Oikos | publisher=Wiley | volume=105 | issue=2 | date=2004-03-22 | issn=0030-1299 | doi=10.1111/j.0030-1299.2004.13173.x | pages=255–267| bibcode=2004Oikos.105..255F }}</ref><ref name="WWB" /> The length of the baculum may be related to the duration of [[copulation (zoology)|copulation]] in some species.<ref>{{cite journal|doi=10.1111/j.1469-7998.1987.tb03718.x|title=Observations on the evolution of the genitalia and copulatory behaviour in male primates|date=1987|last1=Dixson|first1=A. F.|journal=Journal of Zoology|volume=213|issue=3|pages=423–443}}</ref><ref>{{cite journal|doi=10.1016/j.cub.2012.11.001|pmid=23257184|title=The baculum|journal=Current Biology|volume=22|issue=24|pages=R1032–R1033|year=2012|last1=Stockley|first1=Paula|doi-access=free|bibcode=2012CBio...22R1032S }}</ref> In carnivorans<ref>{{cite journal | doi=10.1098/rspb.2020.1883 | title=Postcopulatory sexual selection and the evolution of shape complexity in the carnivoran baculum | year=2020 | last1=Brassey | first1=Charlotte A. | last2=Behnsen | first2=Julia | last3=Gardiner | first3=James D. | journal=Proceedings of the Royal Society B: Biological Sciences | volume=287 | issue=1936 | pmid=33049172 | pmc=7657853 }}</ref> and primates, the length of the baculum appears to be influenced by [[Sexual selection in mammals#Postcopulatory mechanisms|postcopulatory sexual selection]].<ref>{{cite journal | last1=Brindle | first1=Matilda | last2=Opie | first2=Christopher | title=Postcopulatory sexual selection influences baculum evolution in primates and carnivores | journal=Proceedings of the Royal Society B: Biological Sciences | volume=283 | issue=1844 | date=2016-12-14 | issn=0962-8452 | pmid=27974519 | pmc=5204150 | doi=10.1098/rspb.2016.1736 | doi-access=free | article-number=20161736 }}</ref> In some [[bat]] species, the baculum can also protect the [[urethra]] from compression.<ref>{{Cite journal | doi=10.1111/joa.12274| pmid=25655647| pmc=4337662|title = Testing hypotheses of bat baculum function with 3D models derived from microCT| journal=Journal of Anatomy| volume=226| issue=3| pages=229–235|year = 2015|last1 = Herdina|first1 = Anna Nele| last2=Kelly| first2=Diane A.| last3=Jahelková| first3=Helena| last4=Lina| first4=Peter H. C.| last5=Horáček| first5=Ivan| last6=Metscher| first6=Brian D.}}</ref> | ||
== Presence in mammals == | == Presence in mammals == | ||
| Line 33: | Line 33: | ||
== Absence in humans == | == Absence in humans == | ||
Unlike most primates, humans lack a baculum,<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.| s2cid=44416632| doi-access=free}}</ref><ref name="Ankel-Simons2010">{{cite book|author=Friderun Ankel-Simons|title=Primate Anatomy: An Introduction|url=https://books.google.com/books?id=Mwl3M6c5KzoC&q=pensi|date=27 July 2010|publisher=Elsevier|isbn=978-0-08-046911-9}}</ref> but the bone is present, although much reduced, among other [[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 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">{{cite book | last1=Ford | first1=Clellan Stearns | last2=Beach | first2=Frank Ambrose | title=Patterns of Sexual Behavior | publisher=Greenwood Publishing Group | publication-place=Westport, Conn | date=1980-01-01 | isbn=0-313-22355-6 |orig-date=1951}}</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>{{cite journal | last1=Carrion | first1=Hernan | last2=Martinez | first2=Daniel | last3=Parker | first3=Justin | last4=Hakky | first4=Tariq | last5=Bickell | first5=Michael | last6=Boyle | first6=Alexander | last7=Weigand | first7=Luke | last8=Carrion | first8=Rafael | title=A History of the Penile Implant to 1974 | journal=Sexual Medicine Reviews | volume=4 | issue=3 | date=2016 | doi=10.1016/j.sxmr.2016.05.003 | pages=285–293 | pmid=27871961 | url=https://linkinghub.elsevier.com/retrieve/pii/S2050052116300063 | url-access=subscription }}</ref> | Unlike most primates, humans lack a baculum,<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. |s2cid=44416632 |doi-access=free}}</ref><ref name="Ankel-Simons2010">{{cite book |author=Friderun Ankel-Simons |title=Primate Anatomy: An Introduction |url=https://books.google.com/books?id=Mwl3M6c5KzoC&q=pensi |date=27 July 2010 |publisher=Elsevier|isbn=978-0-08-046911-9}}</ref> but the bone is present, although much reduced, among other [[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 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">{{cite book |last1=Ford |first1=Clellan Stearns |last2=Beach |first2=Frank Ambrose |title=Patterns of Sexual Behavior |publisher=Greenwood Publishing Group |publication-place=Westport, Conn |date=1980-01-01 |isbn=0-313-22355-6 |orig-date=1951}}</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>{{cite journal |last1=Carrion |first1=Hernan |last2=Martinez |first2=Daniel |last3=Parker |first3=Justin |last4=Hakky |first4=Tariq |last5=Bickell |first5=Michael |last6=Boyle | first6=Alexander |last7=Weigand |first7=Luke |last8=Carrion |first8=Rafael |title=A History of the Penile Implant to 1974 |journal=Sexual Medicine Reviews |volume=4 |issue=3 |date=2016 |doi=10.1016/j.sxmr.2016.05.003 |pages=285–293 |pmid=27871961 |url=https://linkinghub.elsevier.com/retrieve/pii/S2050052116300063 |url-access=subscription }}</ref> | ||
In ''[[The Selfish Gene]]'', [[Richard Dawkins]]<ref>{{cite book |last=Dawkins |first=R |year=2006 |title=The Selfish Gene |publisher=Oxford University Press |location=Oxford, UK}}</ref> proposed honest advertising as the evolutionary explanation for the loss of the baculum. The hypothesis states that if erection failure is a sensitive early warning of ill health (physical or mental), females could have gauged the health of a potential mate based on his ability to achieve erection without the support of a baculum. | In ''[[The Selfish Gene]]'', [[Richard Dawkins]]<ref>{{cite book |last=Dawkins |first=R |year=2006 |title=The Selfish Gene |publisher=Oxford University Press |location=Oxford, UK}}</ref> proposed honest advertising as the evolutionary explanation for the loss of the baculum. The hypothesis states that if erection failure is a sensitive early warning of ill health (physical or mental), females could have gauged the health of a potential mate based on his ability to achieve erection without the support of a baculum. | ||
The tactile stimulation hypothesis proposes that the loss of the baculum in humans is linked to the female choice for tactile [[sexual stimulation|stimulation]]: a boneless penis would be more flexible, facilitating a larger range of copulatory positions and whole body movement, giving females greater general physical stimulation.<ref>{{cite book | last1=Cormier | first1=Loretta A. | last2=Jones | first2=Sharyn R. | title=The Domesticated Penis: How Womanhood Has Shaped Manhood | publisher=University of Alabama Press | date=2015-11-30 | isbn=978-0-8173-1874-1 |location=Tuscaloosa, USA}}</ref> | The tactile stimulation hypothesis proposes that the loss of the baculum in humans is linked to the female choice for tactile [[sexual stimulation|stimulation]]: a boneless penis would be more flexible, facilitating a larger range of copulatory positions and whole body movement, giving females greater general physical stimulation.<ref>{{cite book |last1=Cormier |first1=Loretta A. |last2=Jones |first2=Sharyn R. |title=The Domesticated Penis: How Womanhood Has Shaped Manhood |publisher=University of Alabama Press |date=2015-11-30 |isbn=978-0-8173-1874-1 |location=Tuscaloosa, USA}}</ref> | ||
The mating system shift hypothesis proposes that the shift towards monogamy as the dominant reproductive strategy may have reduced the intensity of copulatory and post-copulatory sexual selection, and made the baculum obsolete.<ref>{{cite encyclopedia |last=Brennan |first=PLR |year=2016 |title=The evolution of genitalia |editor-last1=Shackelford |editor-first1=TK |editor-last2=Weekes-Shackelford |editor-first2=VA |encyclopedia=Encyclopedia of Evolutionary Psychological Science |publisher= Springer International Publishing |location=Cham, Switzerland}}</ref><ref>{{Cite web |last=London |first=University College |title=Study sheds light on the function of the penis bone in male competition |url=https://phys.org/news/2016-12-function-penis-bone-male-competition.html |access-date=2023-07-15 |website=phys.org |language=en}}</ref> | The mating system shift hypothesis proposes that the shift towards monogamy as the dominant reproductive strategy may have reduced the intensity of copulatory and post-copulatory sexual selection, and made the baculum obsolete.<ref>{{cite encyclopedia |last=Brennan |first=PLR |year=2016 |title=The evolution of genitalia |editor-last1=Shackelford |editor-first1=TK |editor-last2=Weekes-Shackelford |editor-first2=VA |encyclopedia=Encyclopedia of Evolutionary Psychological Science |publisher= Springer International Publishing |location=Cham, Switzerland}}</ref><ref>{{Cite web |last=London |first=University College |title=Study sheds light on the function of the penis bone in male competition |url=https://phys.org/news/2016-12-function-penis-bone-male-competition.html |access-date=2023-07-15 |website=phys.org |language=en}}</ref> | ||
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? |access-date=7 July 2015 | 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? |access-date=7 July 2015 |archive-url=https://web.archive.org/web/20140429220805/http://www.abc.net.au/beasts/evidence/prog1/page4_2.htm |archive-date=29 April 2014 }}</ref>{{Better source 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 [[Copulation (zoology)|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 (unless the cervical mucus is examined),<ref>{{cite web |last1=Ilyich |first1=Iryna |title=Dr |url=https://flo.health/menstrual-cycle/health/vaginal-discharge/discharge-fluid-mucus |website=Flo.health |access-date=1 June 2023}}</ref> 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 |archive-date=19 August 2017 |archive-url=https://web.archive.org/web/20170819153010/http://www.independent.co.uk/life-style/health-and-families/health-news/penis-bone-humans-baculum-sex-doesnt-last-long-enough-ucl-why-a7473401.html |url-status=live}}</ref><ref>{{Cite web |date=2014-04-29 |title=ABC - Science - Beasts - Evidence - Programme 1 - Godinotia |website=[[Australian Broadcasting Corporation]] |url=http://www.abc.net.au/beasts/evidence/prog1/page4_2.htm |archive-url=https://web.archive.org/web/20140429220805/http://www.abc.net.au/beasts/evidence/prog1/page4_2.htm |archive-date=2014-04-29 |access-date=2020-11-23}}</ref> | ||
Strengths and weaknesses of these hypotheses were revised in a 2021 study, which also proposed an alternative hypothesis: that conspecific aggression, in combination with the development of self-awareness, may have played a role in the loss. If the presence of a baculum exacerbated the prevalence and severity of penile injuries resulting from blunt trauma to a flaccid penis, increasing ability to foresee the consequences of their actions would also enable hominins to realise that these injuries are a useful tool in male-male competition. This behavioural innovation, planned conspecific aggression with the goal of temporary exclusion of competitors from the breeding pool, would create an environment in which a genetic mutation for a penis without a baculum (or with an unossified baculum) would strongly increase the fitness of the mutant phenotype. Along with the hominin propensity for social learning and cultural transmission, this hypothetical scenario may explain why this phenotype became fixed in all human populations.<ref name="doi.org">{{cite journal | last=Jakovlić | first=Ivan | title=The missing human baculum: a victim of conspecific aggression and budding self-awareness? | journal=Mammal Review | volume=51 | issue=3 | date=2021 | issn=0305-1838 | doi=10.1111/mam.12237 | pages=454–464 | bibcode=2021MamRv..51..454J | url=https://onlinelibrary.wiley.com/doi/10.1111/mam.12237| url-access=subscription }}</ref> | Strengths and weaknesses of these hypotheses were revised in a 2021 study, which also proposed an alternative hypothesis: that conspecific aggression, in combination with the development of self-awareness, may have played a role in the loss. If the presence of a baculum exacerbated the prevalence and severity of penile injuries resulting from blunt trauma to a flaccid penis, increasing ability to foresee the consequences of their actions would also enable hominins to realise that these injuries are a useful tool in male-male competition. This behavioural innovation, planned conspecific aggression with the goal of temporary exclusion of competitors from the breeding pool, would create an environment in which a genetic mutation for a penis without a baculum (or with an unossified baculum) would strongly increase the fitness of the mutant phenotype. Along with the hominin propensity for social learning and cultural transmission, this hypothetical scenario may explain why this phenotype became fixed in all human populations.<ref name="doi.org">{{cite journal |last=Jakovlić |first=Ivan |title=The missing human baculum: a victim of conspecific aggression and budding self-awareness? |journal=Mammal Review |volume=51 |issue=3 |date=2021 |issn=0305-1838 |doi=10.1111/mam.12237 |pages=454–464 |bibcode=2021MamRv..51..454J |url=https://onlinelibrary.wiley.com/doi/10.1111/mam.12237 |url-access=subscription }}</ref> | ||
An alternative 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> | An alternative 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> | {{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> | "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> | ||
| Line 60: | Line 60: | ||
''Oosik'' ([[Iñupiaq language|Iñupiaq]]: ''usuk'' or ''uzuk'') is a term used in [[Alaska Natives|Alaska Native cultures]] to describe the bacula of [[walrus]]es, [[Phocidae|seals]], [[sea lion]]s and [[polar bear]]s. Sometimes as long as {{Convert|60|cm||abbr=on}}, fossilized bacula are often polished and used as a handle for knives and other tools. The ''oosik'' is a polished and sometimes carved baculum of these large northern carnivores. | ''Oosik'' ([[Iñupiaq language|Iñupiaq]]: ''usuk'' or ''uzuk'') is a term used in [[Alaska Natives|Alaska Native cultures]] to describe the bacula of [[walrus]]es, [[Phocidae|seals]], [[sea lion]]s and [[polar bear]]s. Sometimes as long as {{Convert|60|cm||abbr=on}}, fossilized bacula are often polished and used as a handle for knives and other tools. The ''oosik'' is a polished and sometimes carved baculum of these large northern carnivores. | ||
''Oosiks'' are also sold as tourist souvenirs. In 2007, a {{Convert|4.5|ft||-long|abbr=on|adj=mid|}} fossilized penis bone from an extinct species of walrus, believed by the seller to be the largest in existence, was sold for $8,000.<ref name="4.5foot">{{cite web|url=http://sfgate.com/cgi-bin/article.cgi?f=/n/a/2007/08/26/state/n154935D40.DTL |title=Walrus penis sells for $8,000 at Beverly Hills action |access-date=30 August 2007 |work=AP |archive-url=https://web.archive.org/web/20071106050910/http://www.sfgate.com/cgi-bin/article.cgi?f=%2Fn%2Fa%2F2007%2F08%2F26%2Fstate%2Fn154935D40.DTL |archive-date=6 November 2007 | ''Oosiks'' are also sold as tourist souvenirs. In 2007, a {{Convert|4.5|ft||-long|abbr=on|adj=mid|}} fossilized penis bone from an extinct species of walrus, believed by the seller to be the largest in existence, was sold for $8,000.<ref name="4.5foot">{{cite web|url=http://sfgate.com/cgi-bin/article.cgi?f=/n/a/2007/08/26/state/n154935D40.DTL |title=Walrus penis sells for $8,000 at Beverly Hills action |access-date=30 August 2007 |work=AP |archive-url=https://web.archive.org/web/20071106050910/http://www.sfgate.com/cgi-bin/article.cgi?f=%2Fn%2Fa%2F2007%2F08%2F26%2Fstate%2Fn154935D40.DTL |archive-date=6 November 2007 }}</ref> | ||
[[United States Congressman]] for [[Alaska]], [[Don Young]], was known for possessing an 18-inch walrus ''oosik'', and once brandished it like a sword during a congressional hearing.<ref name="Don Young Oosik">{{cite news |url=https://www.washingtonpost.com/news/the-fix/wp/2018/02/28/a-brief-history-of-alaska-rep-don-youngs-incendiary-remarks-okay-its-a-long-history/ |title=A brief history of Rep. Don Young's incendiary remarks. (All right, it's a long history.) |access-date=18 March 2021 |newspaper=Washington Post |archive-date=5 December 2020 |archive-url=https://web.archive.org/web/20201205032828/https://www.washingtonpost.com/news/the-fix/wp/2018/02/28/a-brief-history-of-alaska-rep-don-youngs-incendiary-remarks-okay-its-a-long-history/ |url-status=live }}</ref> | [[United States Congressman]] for [[Alaska]], [[Don Young]], was known for possessing an 18-inch walrus ''oosik'', and once brandished it like a sword during a congressional hearing.<ref name="Don Young Oosik">{{cite news |url=https://www.washingtonpost.com/news/the-fix/wp/2018/02/28/a-brief-history-of-alaska-rep-don-youngs-incendiary-remarks-okay-its-a-long-history/ |title=A brief history of Rep. Don Young's incendiary remarks. (All right, it's a long history.) |access-date=18 March 2021 |newspaper=Washington Post |archive-date=5 December 2020 |archive-url=https://web.archive.org/web/20201205032828/https://www.washingtonpost.com/news/the-fix/wp/2018/02/28/a-brief-history-of-alaska-rep-don-youngs-incendiary-remarks-okay-its-a-long-history/ |url-status=live }}</ref> | ||
Latest revision as of 21:18, 29 December 2025
Template:Short description Script error: No such module "Distinguish". Template:Use dmy dates
The baculum (Template:Plural form: bacula), also known as the penis bone, penile bone, os penis, os genitale,[1] or os priapi,[2] is a bone in the penis of many placental mammals. It is not present in humans, but is present in the penises of some primates, such as the gorilla and the chimpanzee.[3][4] The baculum arises from primordial cells in soft tissues of the penis, and its formation is largely influenced by androgens.[5] The bone lies above the urethra,[6] and it aids sexual reproduction by maintaining stiffness during sexual penetration. The homologue to the baculum in female mammals is the baubellum (os clitoridis), a bone in the clitoris.[7][8][9]
Etymology
The word baculum means "stick" or "staff" in Latin and originates from Template:Langx, baklon "stick".[10]
Function
The baculum is used for copulation and varies in size and shape by species. Its evolution may be influenced by sexual selection, and its characteristics are sometimes used to differentiate between similar species.[11] A bone in the penis allows a male to mate for a long time with a female,[12][13][14] which can be a distinct advantage in some mating strategies.[15][16] The length of the baculum may be related to the duration of copulation in some species.[17][18] In carnivorans[19] and primates, the length of the baculum appears to be influenced by postcopulatory sexual selection.[20] In some bat species, the baculum can also protect the urethra from compression.[21]
Presence in mammals
The baculum is absent in monotreme (egg-laying) and marsupial (pouch-bearing) mammals. Mammals having a penile bone include various eutherians (placental mammals):
- Order Primates, although not in humans, lorises,[22] spider monkeys, or woolly monkeys[23]
- Order Rodentia (rodents),[24] though not in the related order Lagomorpha (rabbits, hares, etc.)[25]
- Order Eulipotyphla[26] (insectivores, including shrews and hedgehogs)
- Order Carnivora[9] (including members of many well-known families, such as ursids (bears),[27] canids (dogs),[1] pinnipeds (walruses, seals, sea lions),[6] procyonids (raccoons etc.),[28] mustelids (otters, weasels, skunks and others).[29] The baculum is usually longer in the Canoidea than in the Feloidea, although fossas have long bacula and giant pandas have short bacula.[9] However, the baculum is notably absent in carnivorans such as hyenas and binturongs
- Order Chiroptera (bats).[30][31][32]
Within Eutheria, the penile bone is absent in ungulates (hoofed mammals, including cetaceans (whales, dolphins, and porpoises)),[33] elephants, lagomorphs,[25][34][26] and sirenians[6] among others.
Evidence suggests that the baculum was independently evolved 9 times and lost in 10 separate lineages.[26] The baculum is an exclusive characteristic of placentals and closely related eutherians, being absent in other mammal clades, and it has been speculated to be derived from the epipubic bones more widely spread across mammals, but notoriously absent in placentals.[35]
Among the primates, marmosets,Script error: No such module "Unsubst". weighing around Script error: No such module "convert"., have a baculum measuring around Script error: No such module "convert"., while the tiny Script error: No such module "convert". galago has one around Script error: No such module "convert". long. The great apes, despite their size, tend to have very small penis bones, and humans are the only ones to have lost them altogether.[16]
In some mammalian species, such as badgers[36][37] and raccoons (Procyon lotor), the baculum can be used to determine relative age. If a raccoon's baculum tip is made up of uncalcified cartilage, has a porous base, is less than Script error: No such module "convert". in mass, and measures less than Script error: No such module "convert". long, then the baculum belongs to a juvenile.[28]
Absence in humans
Unlike most primates, humans lack a baculum,[38][39] but the bone is present, although much reduced, among other great apes. In many ape species, it is a relatively insignificant Script error: No such module "convert". structure. Cases of human penis ossification following trauma have been reported,[40] 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 cleft scrotum.[41] 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."[4] In humans, the rigidity of the erection is provided entirely through blood pressure in the corpora cavernosa. An "artificial baculum" or penile implant is sometimes used to treat erectile dysfunction in humans.[42]
In The Selfish Gene, Richard Dawkins[43] proposed honest advertising as the evolutionary explanation for the loss of the baculum. The hypothesis states that if erection failure is a sensitive early warning of ill health (physical or mental), females could have gauged the health of a potential mate based on his ability to achieve erection without the support of a baculum.
The tactile stimulation hypothesis proposes that the loss of the baculum in humans is linked to the female choice for tactile stimulation: a boneless penis would be more flexible, facilitating a larger range of copulatory positions and whole body movement, giving females greater general physical stimulation.[44]
The mating system shift hypothesis proposes that the shift towards monogamy as the dominant reproductive strategy may have reduced the intensity of copulatory and post-copulatory sexual selection, and made the baculum obsolete.[45][46]
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"[16]Template:Better source needed 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 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 (unless the cervical mucus is examined),[47] so frequent matings would be necessary to ensure paternity.[16][48][49]
Strengths and weaknesses of these hypotheses were revised in a 2021 study, which also proposed an alternative hypothesis: that conspecific aggression, in combination with the development of self-awareness, may have played a role in the loss. If the presence of a baculum exacerbated the prevalence and severity of penile injuries resulting from blunt trauma to a flaccid penis, increasing ability to foresee the consequences of their actions would also enable hominins to realise that these injuries are a useful tool in male-male competition. This behavioural innovation, planned conspecific aggression with the goal of temporary exclusion of competitors from the breeding pool, would create an environment in which a genetic mutation for a penis without a baculum (or with an unossified baculum) would strongly increase the fitness of the mutant phenotype. Along with the hominin propensity for social learning and cultural transmission, this hypothetical scenario may explain why this phenotype became fixed in all human populations.[50]
An alternative view is that its loss in humans is an example of neoteny during human evolution; late-stage fetal chimpanzees lack a baculum.[51]
Cultural significance
_Bacalum_Morse.jpg){kind=link}
It has been argued that the "rib" (Hebrew צֵלׇע ṣēlāʿ, also translated "flank" or "side") in the story of Adam and Eve is actually a mistranslation of a Biblical Hebrew euphemism for baculum, and that its removal from Adam in the Book of Genesis is a creation story to explain this absence (as well as the presence of the perineal raphe – as a resultant "scar") in humans.[52]
In Hoodoo, the folk magic of the American South, the raccoon baculum is sometimes worn as an amulet for love or luck.[53]
Oosik
Oosik (Iñupiaq: usuk or uzuk) is a term used in Alaska Native cultures to describe the bacula of walruses, seals, sea lions and polar bears. Sometimes as long as Script error: No such module "convert"., fossilized bacula are often polished and used as a handle for knives and other tools. The oosik is a polished and sometimes carved baculum of these large northern carnivores.
Oosiks are also sold as tourist souvenirs. In 2007, a Script error: No such module "convert". fossilized penis bone from an extinct species of walrus, believed by the seller to be the largest in existence, was sold for $8,000.[54]
United States Congressman for Alaska, Don Young, was known for possessing an 18-inch walrus oosik, and once brandished it like a sword during a congressional hearing.[55]
See also
- Argumentum ad baculum – Latin expression describing an argument based on the use of force.
- Mammal penis
- Penile spines
References
<templatestyles src="Reflist/styles.css" />
- ↑ a b Script error: No such module "citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ a b Script error: No such module "citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ a b c Script error: No such module "citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ a b c Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ a b c d Script error: No such module "citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ a b Script error: No such module "citation/CS1".
- ↑ a b c Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ a b Script error: No such module "citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "citation/CS1". (page 134), cited by:
Script error: No such module "Citation/CS1".
"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'" - ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
Script error: No such module "Check for unknown parameters".
Further reading
- Script error: No such module "Citation/CS1".
- Script error: No such module "citation/CS1".
External links
Template:Sister project Template:Sister project
- Script error: No such module "Citation/CS1".
- The San Diego Zoo's Conservation and research for endangered species projects. 'What is the significance of the baculum in animals?'
- Script error: No such module "Citation/CS1".
- The structure of the penis with the associated baculum in the male greater cane rat (Thryonomys swinderianus)
- Script error: No such module "citation/CS1".