#Chimpanzee penis update
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' Evolution of sexual size monomorphism: the influence of passive mate guarding.' Journal of evolutionary biology 22.7 (2009): 1376-1386. ' On the function of the multiple-intromission, multiple-ejaculation copulatory patterns of rodents.' Bulletin of the Psychonomic Society 18.4 (1981): 221-223. 'Observations on the evolution of the genitalia and copulatory behaviour in male primates'. ' Sexual selection and genital anatomy of male primates.' Proc.

^ Larry Vogelnest Rupert Woods (18 August 2008).

' Exposure to naturally circulating androgens during foetal life incurs direct reproductive costs in female spotted hyenas, but is prerequisite for male mating.' Proceedings of the Royal Society of London B: Biological Sciences 269.1504 (2002): 1981-1987. Current Therapy in Medicine of Australian Mammals.

#Chimpanzee penis update

' Wombat reproduction (Marsupialia Vombatidae): an update and future directions for the development of artificial breeding technology.' Reproduction 145.6 (2013): R157-R173.

^ Hogan, Lindsay A., Tina Janssen, and Stephen D.

A histological study of the development of the penis of wild-type and androgen-insensitive mice. Note on the male external genitalia of the chimpanzee. ' Reproductive status of endemic felid species in Latin American zoos and implications for ex situ conservation.' Zoo Biology 22.5 (2003): 421-441. 'Penile Spines of the Domestic Cat: Their Endocrine-behavior Relations' (PDF). Asdell's Patterns of Mammalian Reproduction: A Compendium of Species-specific Data.

^ Virginia Douglass Hayssen Ari Van Tienhoven (1993).

Archived at the Wayback Machine' Evolutionary Ecology 16.2 (2002): 123-137. ' Sperm competition risk and male genital anatomy: comparative evidence for reduced duration of female sexual receptivity in primates with penile spines. ' All Features Great and Small-the Potential Roles of the Baculum and Penile Spines in Mammals.' Integrative and Comparative Biology (2016): icw057.

^ Orr, Teri J., and Patricia LR Brennan.

Primate Sexuality: Comparative Studies of the Prosimians, Monkeys, Apes, and Humans. The penises of some bird species feature spines and brush-like filaments. An hCONDEL (highly conserved region of DNA that contains deletions in humans) located near the locus of the androgen receptor gene may be responsible for the loss of penile spines in humans.

#Chimpanzee penis full

In some species which retain full expression, penile spines contribute to increased sexual sensation and quicker orgasms. This simplification of penis anatomy may be associated with the sexual habits of humans. When the hominin lineage split into the genera Homo and Pan, a regulatory DNA sequence associated with the formation of small keratinized penile spines was lost in the Homo lineage. However, the relationship between the structures is still uncertain. These are sometimes described as vestigial remnants of penile spines. In contrast to chimpanzees, a common morphological variant found in humans called hirsuties coronae glandis, or pearly penile papules, are substantially larger, appear to be an outpocketing of both surface and underlying connective tissue layers, and lack the rich innervation seen in other animals. In galagos, penile spines may form a 'genital lock' during copulation. Penile spines are often found in primate species that form copulatory plugs after mating.

They occur in wombats, koalas, spotted hyenas, fossas, echidnas, primates, bats, and several rodent species.

#Chimpanzee penis skin

Penile spines in chimpanzees and mice are small surface projections made by the piling up of keratinized cell layers in the outermost skin surface. Many other felid species have penile spines, but they are relatively small in jaguars and pumas, and do not occur in margays.

Upon withdrawal of a cat's penis, the spines rake the walls of the female's vagina, which may serve as a trigger for ovulation. Further information: Spotted hyena § Female genitalia, Fossa (animal) § External genitalia, and Cat § Reproductionįelines, especially domestic cats, are well known for having penile spines.