Penis bones are a curious thing . Known as a baculum , alarge number of male mammals , from bear and tigers to ferret and elephant seals , have develop a rigid , mineralized , stick - like bone through the center of their member . It also happen to be one of the mostmorphologically diversebones in the man . However , many species of mammals do not feature any such penis bone – most notably us , humans – leaving some researchers to wonder what role it do .
allot to a newfangled subject , the penis bone in some coinage might have evolved for an act of “ post - copulatory intimate contender ” that involves scooping rivals ’ sperm cell out of the female . Whether or not a species indulges in this dirty trick can be visualize in the shape and size of it of the ivory , and also appear to reflect the animals ’ social anatomical structure .
As report in theProceedings of the Royal Society B , scientists from the Manchester Metropolitan University in the UK set out to understand the different configuration and sizes of penis off-white recover among carnivorous mammalian . Using picture obtained through 3D scanning and computer simulation techniques fromtheir previous work , they study the dissimilar baculums of 82 mintage of carnivores , including the red giant panda , Baron Snow of Leicester Panthera pardus , southern elephant seals , browned bear , honey badger , European otter , and tigers .
Their analysis uncover some interesting trend . more often than not speak , they find that animals with penis finger cymbals that were round-eyed , smooth , and square were more probable to be multiple - married person species or “ group living ” species , such as elephant seals , Charles Grey seals , and walruses . In this scenario , just a small telephone number of successful male are able to breed with a harem of females , meaning sperm cell competition is often pretty downcast .
On the other hand , beast with a gnarly and complex - shaped baculum with rum tips were more potential to be socially monogamous . While you might assume a strong and stable relationship signify sperm cell competition is low , it can also intend that males are more eager to assure their authorship and sperm competition can remain gamey . Equally , socially monogamy does n’t of necessity mean genetic monogamy ; extra - yoke copulation , a promiscuous mating behavior , is found in many monogamous species . As such , the researchers believe the complexly shaped bones of some species could be a tool for “ postcopulatory sexual selection ” involving the remotion of others ’ spermatozoon from the female .
" They ’re very surprising and counterintuitive results , we initially require the inverse , " Dr Charlotte Brassey , lead study author and lecturer in Zoology at Manchester Metropolitan University , told IFLScience .
" When we find that dogs in ’ socially monogamous ’ pairs actually have really complex bacula , I opine that ’s because their bacula has anatomical adaptations that are actually useful when the Male are trying to guard against another sneaky male person trying the first mate with the female . We know this can be quite coarse in canine , " explicate Dr Brassey .
" And likewise , when we bump that ‘ group living ’ species like the land - breeding pinniped have dewy-eyed bacula , I call up that ’s because their ‘ harem - like ’ mating organization in reality intend the prevalent males do a really good job of preventing any ’ sneaky ’ matings , so they require to worry less about another male person ’s spermatozoon , " they added .
There might be more to the write up , however . The investigator note that many member also boast a chunky piece of gristle that fence the bone , castrate the overall shape of the member . regrettably , this is missing from most museum specimens , which only consist of an ossified bone . Very little is also known about the other half of the narration : the three - dimensional soma of female genitalia see in mammal . This means some of the assumption about phallus shape acting as poking rods or scoop may not be strictly right .
Nevertheless , the long - standing mysteryof the penis bone is starting to be expose .
