Penis bones

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Penis bones of a dog ; the arrow points to the groove for the urethra on the underside . The front end is on the right.

The penis bone ( Latin os penis, os priapi, baculum , for stick / stick ) is a bone in the male reproductive organ ( penis ) of many mammals , which is not articulated with other bones and takes on a variety of functions during copulation. Penile bones are widespread among mammals and primates as well, so the absence of such a structure in humans is an exception. In some female mammals, a clitoral bone ( Os clitoridis , also Baubellum) occurs as an equivalent to the penis bone .

Occurrence

Penis bones can be found in the following groups of animals:

Ungulates , whales , elephants and manatees , monotremes and marsupials do not have a penis bone.

The walrus has the largest penis bone , the smallest the pipistrellus pipistrelle. Fossil , the structure is particularly known from the cave bear ( Ursus spelaeus ).

Structure and location

Fossil penis bones of a bear from the Miocene .

The penis bone is part of the male genitalia and represents an ossification of the penis cavernous body ( corpus cavernosum penis ). It extends backwards from the glans along the penis shaft. The part directed furthest towards the tail is called the base , and the front end is called the apex or simply tip . The middle piece is called the body . Because the penis bone is tightly attached to the urethra, the bone has an indentation pointing towards the abdomen, the sulcus urethrae . In cross-section, a penis bone therefore appears to be inverted U-shaped in some animals (e.g. in domestic dogs).

For wolves it has been shown that the penis bone scales positively allometrically to body size within the species . That is, the larger the individual, the larger the penis bone is relative to the rest of the body. The size of penis bones in relation to the rest of the body can vary greatly between different species: while the marmoset, weighing 500 g, has a penis bone around 2 mm in length, the ten times lighter Galagos have penis bones up to 13 mm in length.

Although it is usually bony, it may only be cartilaginous in some mammals . Since the morphology of the penis bone is very species-specific, it is occasionally used to distinguish closely related species ( systematics ). It can also be used in some animal species to determine the age at the time of death, as its tip only ossifies in adult animals and only then reached its full length.

function

The exact function of the penis bone is still being debated. However, several studies suggest that the penis bone supports the rigidity of the penis during copulation. This allows the males a relatively long act of mating. A work from 2015, which deals with the penis bone function in bats, confirms this hypothesis, but also suggests a possible second function: the protection of the urethra and the urinary opening from obstruction during copulation.

Furthermore, the penis bone could play an important role in the transport of the sperm, as in some species it protrudes beyond the end of the glans and may even be in contact with the clitoris bone of the female during copulation. In species with induced ovulation, stimulation of the female genitals with the penis bone could be a possible trigger.

Evolutionary causes for the formation or reduction of the penile bone

A raccoon's penis bones made into jewelry

Since both the absence and presence of penile bones are common among mammals, both conditions appear to have an evolutionary advantage. The species-specific reproductive behavior could play a decisive role in whether species have a penis bone or whether it is reduced. For example, it has been speculated for humans that penile bones may have been reduced with the establishment of monogamous reproductive strategies. The permanent accompaniment of the female by the male allows numerous sexual contacts, which can sometimes be very short, as well as full control over the resulting paternity.

Primates, which only rarely meet their peers, would therefore have penis bones in order to maximize the chance of their own fatherhood through long sexual acts. Also, penises equipped with penis bones are more quickly ready for copulation due to their permanent rigidity, when the rare opportunity for mating presents itself, than penises that are based solely on a hydraulic principle.

Cultural meaning

The penis bones of different animals acquired a certain importance in different cultures, which is closely linked to the function of the bones in the act of mating. The penis bone of the raccoon, for example, is worn as an amulet in the hoodoo tradition in the southern states of the USA , which is supposed to help the wearer to love and happiness .

Walrus penis bones, approximate length: 60 cm.

The penis bones of male walruses , referred to as oosik by native Alaska cultures , are often polished and used as handles for knives and other tools, or sold to tourists as souvenirs. Penis bones may even have played a role in the constitution and transmission of biblical scriptures. It was suggested that the rib of Adam, from which God created Eve in the creation story , actually meant the penis bone. The rib would be a mistranslation of a Hebrew euphemism for penis bones . Following this view, this would explain the lack of a penis bone in men and the existence of the raphe penis as a supposed "scar" of this operation.

literature

Web links

Commons : Penis bones  - collection of pictures, videos and audio files

Individual evidence

  1. ↑ Clellan S. Ford, Frank A. Beach: Patterns of Sexual Behavior Harper & Row, New York 1951, ISBN 0-313-22355-6 .
  2. ↑ Reproduction: Why Men Don't Have a Penis Bone In: Spiegel Online from December 14, 2016
  3. ↑ Postcopulatory sexual selection influences baculum evolution in primates and carnivores In: Proceedings of the Royal Society of December 14, 2016
  4. ^ RH Champion, J. Wegrzyn: Congenital os penis . In: Journal of Urology . 91, 1964, pp. 663-4.
  5. ^ RF Ewer: The Carnivores. Cornell University Press, 1973, ISBN 0-8014-8493-6 , ( books.google.com )
  6. ^ Markus G. Dyck, Jackie M. Bourgeois, Edward H. Miller: Growth and variation in the bacula of polar bears ( Ursus maritimus ) in the Canadian Arctic . In: Journal of Zoology . 264, No. 1, 2004, pp. 105-110. doi : 10.1017 / S0952836904005606 .
  7. ^ Howard E. Evans, Alexander de Lahunta: Miller's Anatomy of the Dog. Elsevier Health Sciences, August 7, 2013, ISBN 978-0-323-26623-9 . ( books.google.com )
  8. ^ A b c William F. Perrin, Bernd Wursig, JGM Thewissen: Encyclopedia of Marine Mammals. 2009, ( books.google.de )
  9. ^ Richard Estes: The Behavior Guide to African Mammals. Including Hoofed Mammals, Carnivores, Primates. University of California Press 1991, ISBN 0-520-08085-8 , p. 323 ff. ( Books.google.com )
  10. ↑ John E. Harkness, Patricia V. Turner, Susan VandeWoude, Colette L. Wheler: Harkness and Wagner's Biology and Medicine of Rabbits and Rodents. John Wiley & Sons, 2013, ISBN 978-1-118-70907-8 . ( books.google.com )
  11. ↑ Ronald M. Nowak: Walker's Mammals of the World. JHU Press, 1999, ISBN 0-8018-5789-9 , p. 1007 ff. ( Books.google.com )
  12. ^ Frederick S. Szalay: Evolutionary History of the Marsupials and an Analysis of Osteological Characters. Cambridge University Press, 2006, ISBN 0-511-56557-7 , pp. 293 ff. ( Books.google.com ).
  13. ↑ TO Herdina, H. Plenk Jr, P. Benda, PHC Lina, B. Herzig-Straschil, H. Hilgers, BD Metscher: Correlative 3D-imaging of Pipistrellus penis micromorphology. Validating quantitative microCT images with undecalcified serial ground section histomorphology. In: Journal of Morphology.
  14. ^ ME Miller, GC Christensen, HE Evans: Anatomy of the Dog. In: Academic Medicine. 40 (4), 1965, p. 400.
  15. ↑ A. Canady, Ľ. Čomor: Allometry of the baculum in the wolf (Canis lupus, Canidae) as an indicator of viability and quality in males. In: Zoology and Ecology. 25 (3), 2015, pp. 192-198.
  16. ↑ AN Herdina, P. Hulva, I. Horácek, P. Benda, C. Mayer, H. Hilgers, BD Metscher: MicroCT imaging reveals morphometric baculum differences for discriminating the cryptic species Pipistrellus pipistrellus and P. pygmaeus. In: Acta Chiropterologica, 16 (1), 2014. pp. 157-168.
  17. ^ Nova J. Silvy: The Wildlife Techniques Manual. Volume 1: Research. Volume 2: Management. JHU Press, 2012, ISBN 978-1-4214-0159-1 . ( books.google.com ).
  18. ^ A. Sharir, D. Israeli, J. Milgram, JD Currey, E. Monsonego-Ornan, R. Shahar: The canine baculum: The structure and mechanical properties of an unusual bone. In: Journal of structural biology. 175 (3), 2011. pp. 451-456.
  19. ↑ a b A. F. Dixson: Baculum length and copulatory behavior in carnivores and pinnipeds (Grand Order Ferae). In: Journal of Zoology. 235.1, 1995, pp. 67-76.
  20. ↑ TO Herdina, DA Kelly, H. Jahelková, PH Lina, I. Horáček, BD Metscher: Testing hypotheses of bat baculum function with 3D models derived from microCT. In: Journal of Anatomy. 226.3, 2015, pp. 229–235.
  21. ↑ Godinotia . In: Walking With Beasts . ABC - BBC. S. Question: How do we know how Godinotia (the primate in program 1) mated ?. 2002. Archived from the original on April 29, 2014. Retrieved on July 7, 2015.
  22. ↑ Joanne O'Sullivan: Book of Superstitious Stuff. Weird Happenings, Wacky Rites, Frightening Fears, Mysterious Myths & Other Bizarre Beliefs. Charlesbridge Publishing, 2010, ISBN 978-1-60734-367-7 , p. 87. ( books.google.com ).
  23. ↑ Walrus penis sells for $ 8,000 at Beverly Hills action . In: AP . Archived from the original on November 6, 2007. Retrieved August 30, 2007.
  24. ↑ SF Gilbert, Z. Zevit: Congenital human baculum deficiency: The generative bone of Genesis 2: 21-23 . In: American Journal of Medical Genetics . 101, No. 3, 2001, pp. 284-5. doi : 10.1002 / ajmg.1387 . PMID 11424148 .