Female hyenas don't have penises, but it sure looks like they do - and we still aren't quite sure why.

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To learn more, start your googling with these keywords: Pseudopenis: a structure that resembles a penis but is developmentally (and functionally) different Masculinization: the process by which female genitalia is made to appear more like male genitalia

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If you liked this week’s video, you might also like: Why It Sucks to Be a Male Hyena https://www.youtube.com/watch?v=PBCNWmU5apE

Hyena having a baby at the Buffalo Zoo https://www.youtube.com/watch?v=7rd7TvoPtWM

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Credits (and Twitter handles): Script Writer: Kate Yoshida (@KateYoshida) Script Editor: Alex Reich (@alexhreich) Video Illustrator: Ever Salazar (@eversalazar) Video Director: Kate Yoshida (@KateYoshida) Video Narrator: Kate Yoshida (@KateYoshida) With Contributions From: Henry Reich, Emily Elert, Peter Reich, David Goldenberg Music by: Nathaniel Schroeder: http://www.soundcloud.com/drschroeder

Video Credits: Spotted Hyenas Mating - Olivia Spagnuolo

Image Credits: Female Spotted Hyena - Kate Yoshida Spotted Hyena Pseudopenis - Kay Holekamp

Striped Hyena (Hyaena hyaena) - Flickr user Jean https://www.flickr.com/photos/7326810@N08/3091611374

Brown Hyena (Parahyaena brunnea) - Bernard DUPONT https://www.flickr.com/photos/berniedup/6472940707/

Proteles cristatus - Dominik Käuferle https://commons.wikimedia.org/wiki/File:Proteles_cristatus1.jpg

Squirrel monkey - Wikimedia user Megapixie https://commons.wikimedia.org/wiki/File:Squirrel_monkey-_fuji.jpg

Ring tailed lemur - Wikimedia user Sannse https://commons.wikimedia.org/wiki/File:Ring_tailed_lemur_and_twins.jpg

Fossa - Ran Kirlian https://commons.wikimedia.org/wiki/File:Cryptoprocta_Ferox.JPG

Binturong - Tassilo Rau https://commons.wikimedia.org/wiki/File:Binturong_in_Overloon.jpg

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References:

Cunha GR, Risbridger G, Wang H, Place NJ, Grumbach M, Cunha TJ, Weldele M, Conley AJ, Barcellos D, Agarwal S, Bhargava A, Drea C, Hammond GL, Siiteri P, Coscia EM, McPhaul MJ, Baskin LS, Glickman SE. (2014) Development of the external genitalia: perspectives from the spotted hyena (Crocuta crocuta). Differentiation. 87(1-2):4-22. http://www.sciencedirect.com/science/article/pii/S030146811300087X?via%3Dihub

Frank LG (1997) Evolution of genital masculinization: why do female hyenas have such a large 'penis'? Trends Ecol. Evol. 12:58-62. http://www.cell.com/trends/ecology-evolution/abstract/S0169-5347(96)10063-X

Frank LG and Glickman SE (1994) Giving birth through a penile clitoris: parturition and dystocia in the spotted hyaena (Crocuta crocuta). J. Zool. 234:659–665. http://onlinelibrary.wiley.com/doi/10.1111/j.1469-7998.1994.tb04871.x/abstract

Frank LG, Weldele ML, and Glickman SE (1995) Masculinization costs in hyaenas. Nature 377:584–585. http://www.nature.com/nature/journal/v377/n6550/abs/377584b0.html?foxtrotcallback=true

Glickman SE, Cunha GR, Drea CM, Conley AJ and Place NJ (2006) Mammalian sexual differentiation: lessons from the spotted hyena. rends in Endocrinology and Metabolism 17 (9): 349–356. http://www.sciencedirect.com/science/article/pii/S1043276006001767

Holekamp, KE, personal communication. August and September 2017.

Muller MN and Wrangham R (2002) Sexual Mimicry in Hyenas. The Quarterly Review of Biology 77 (1):3-16. http://www.journals.uchicago.edu/doi/abs/10.1086/339199?journalCode=qrb