![]() ![]() Seasonal breeding patterns adds to the intensity because mating only happens during a restricted period of time. In promiscuous species, the risk that a female is inseminated by another male before the sperm of the first male have managed to fertilise the female's eggs is high. The third interesting fact is that the longer intromission (the time the penis spends in the vagina) lasts, the longer the penis bone tends to be. Species with clear mating seasons, as opposed to mating throughout the year, also have longer baculae. the more promiscuous the species, the longer the bacula. The study found that there was a clear relationship between the length of the penis bone and the level of promiscuity of the species, i.e. The key concept to understanding the above is "promiscuity". ![]() Some experts believe that a bacula might allow for easier penile manoeuvring during intercourse while others think that the bone may stimulate the female reproductive tract, causing the ovaries to release eggs.Īn article published by The Royal Society in December 2016 suggests that "the baculum plays an important role in facilitating reproductive strategies in populations with high levels of postcopulatory sexual selection" (consecutive acts of copulation). ![]() When the sexual stimulus disappears, the arteries in the penis become narrower again, which lets the blood drain from the corpora cavernosa, allowing it to become flaccid.Īs a penis bone doesn’t seem to be essential for successful penetration, intercourse and procreation, there are a number of theories why it is present in some species and not in others.Īs mentioned above, a penis bone may help with erections, but this isn’t the only theory. This “swelling” blocks the veins that would normally allow blood to flow out of the penis. Two cylindrical chambers (corpora cavernosa) that act like sponges become engorged with blood, causing the penis to swell up and stiffen. The way an an erection happens is as follows: Sexual arousal causes the brain to send chemical messages to the nerves in the penis, causing blood vessels to relax and allow blood to flow freely into the penis. Hypotheses about causation, however, require scrutiny with a more complete dataset from living subjects.The baculum certainly helps to keep the penis stiff, but human males (and many other species) manage to get and stay erect without it. Similarities and differences in penile structure between Pongo, which has a non-gregarious (dispersed) mating system, and Pan (with a multimale system) may be understood in relation to the form of the female genitalia this is consistent with the notion that sexual selection by female choice may be an ultimate cause of sexual characteristics of hominoids. Relative to size of males, however, Homo have pars libera that are twice as long as those of Pongo. ![]() Comparisons of the length of the pars libera relative to size of females across the great apes and humans (Homo) reveals that the pars libera of Pan is much longer than that of Homo which is longer than but similar to that of Pongo, which is much longer than that of Gorilla. The pars libera was much longer than previously represented in comparative analyses, and most were filiform (as in Pan), but form and color was variable: 1) a partially or completely demarcated glans-like structure (as in Gorilla) was present in a few subjects 2) epidermal specializations of the pars distalis had either a hinge-like or flap-like form and might be homologous to the keratinized spines seen in other species 3) the pars libera was not a uniform pink in all cases as the pars medialis often was black or purple. Size and form of the external penis, or pars libera, was documented for 17 living orang-utans (Pongo pygmaeus) of varying age. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |