{"page":"\u003clink rel=\"stylesheet\" href=\"https://lessonplanet.com/assets/packs/css/resources-572d6a42.css\" /\u003e\n\u003clink rel=\"stylesheet\" href=\"https://lessonplanet.com/assets/packs/css/lp_boclips_stylesheets-f4d0de30.css\" media=\"all\" /\u003e\n\u003cdiv data-title='Why Bird Penises Are So Weird' data-url='/boclips/videos/625f61f9ba74a438580d6d01' data-video-url='/boclips/videos/625f61f9ba74a438580d6d01' id='bo_player_modal'\u003e\n\u003cdiv class='boclips-resource-page modal-dialog panel-container'\u003e\n\u003cdiv class='react-notifications-root'\u003e\u003c/div\u003e\n\u003cdiv class='rp-header'\u003e\n\u003cdiv class='rp-type'\u003e\n\u003ci aria-hidden='true' class='fai fa-regular fa-circle-play'\u003e\u003c/i\u003e\nVideo\n\u003c/div\u003e\n\u003ch1 class='rp-title' id='video-title'\u003e\nWhy Bird Penises Are So Weird\n\u003c/h1\u003e\n\u003cdiv class='rp-actions'\u003e\n\u003cdiv class='mr-1'\u003e\n\u003ca class=\"btn btn-success\" data-posthog-event=\"Signup: LP Signup Activity\" data-posthog-location=\"body_link_boclips\" data-remote=\"true\" href=\"/subscription/new\"\u003e\u003cspan\u003e\u003cspan\u003eGet Free Access\u003c/span\u003e\u003cspan class=\"\"\u003e for 10 Days\u003c/span\u003e\u003cspan\u003e!\u003c/span\u003e\u003c/span\u003e\u003c/a\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv class='rp-body'\u003e\n\u003cdiv class='rp-info'\u003e\n\u003cdiv aria-label='Hide resource details' class='rp-hide-info' role='button' tabindex='0'\u003e\u0026times;\u003c/div\u003e\n\u003ci aria-label='Expand resource details' class='rp-expand-info fai fa-solid fa-up-right-and-down-left-from-center' role='button' tabindex='0'\u003e\u003c/i\u003e\n\u003ci aria-label='Compress resource details' class='rp-compress-info fai fa-solid fa-down-left-and-up-right-to-center' role='button' tabindex='0'\u003e\u003c/i\u003e\n\u003cdiv class='rp-rating'\u003e\n\u003cspan class='resource-pool'\u003e\n\u003cspan class='pool-label'\u003ePublisher:\u003c/span\u003e\n\u003cspan class='pool-name'\u003e\n\u003cspan class='text'\u003e\u003ca data-publisher-id=\"30358007\" href=\"/search?publisher_ids%5B%5D=30358007\"\u003eMinuteEarth\u003c/a\u003e\u003c/span\u003e\n\u003c/span\u003e\n\u003c/span\u003e\n\u003c/div\u003e\n\u003cdiv class='rp-description'\u003e\n\u003cspan class='short-description'\u003eThanks to 23andMe for sponsoring this video! Male birds have the largest genital diversity of any class of animals because their sex chromosomes make it easy to pass male-helping mutations down the line. Thanks also to our supporters on...\u003c/span\u003e\n\u003cspan class='full-description hide'\u003eThanks to 23andMe for sponsoring this \u003ca href='https://www.23andme.com/minuteearth' target='_blank' rel='nofollow'\u003evideo!\u003c/a\u003e Male birds have the largest genital diversity of any class of animals because their sex chromosomes make it easy to pass male-helping mutations down the line. Thanks also to our supporters \u003ca href='https://www.patreon.com/MinuteEarth' target='_blank' rel='nofollow'\u003eon\u003c/a\u003e ___________________________________________ To learn more, start your googling with these keywords: Sex chromosome: A chromosome involved in determining the sex of an individual. Cloaca: A posterior orifice that serves as the only exit for the gastrointestinal, urinary and genital tracts. Mutation: An alteration in the DNA sequence that makes up a gene. Sexually-selected Trait: A trait based on a mutation that confers a reproductive advantage. BMP4: A protein whose presence halts the growth of bird penises in the egg. ___________________________________________ If you liked this week’s video, you might also like: An article from The Week about some of the strangest penises in the animal \u003ca href='http://theweek.com/articles/474417/12-weirdest-animal-penises-earth-updated' target='_blank' rel='nofollow'\u003ekingdom\u003c/a\u003e _________________________________________ Subscribe to MinuteEarth on \u003ca href='http://goo.gl/EpIDGd' target='_blank' rel='nofollow'\u003eYouTube\u003c/a\u003e Support us on \u003ca href='https://goo.gl/ZVgLQZ' target='_blank' rel='nofollow'\u003ePatreon\u003c/a\u003e And visit our \u003ca href='https://www.minuteearth.com/' target='_blank' rel='nofollow'\u003ewebsite\u003c/a\u003e Say hello on \u003ca href='http://goo.gl/FpAvo6' target='_blank' rel='nofollow'\u003eFacebook\u003c/a\u003e And \u003ca href='http://goo.gl/Y1aWVC' target='_blank' rel='nofollow'\u003eTwitter\u003c/a\u003e And download our videos on \u003ca href='https://goo.gl/sfwS6n' target='_blank' rel='nofollow'\u003eitunes\u003c/a\u003e ___________________________________________ Credits (and Twitter handles): Script Writer: David Goldenberg (@dgoldenberg) Script Editor: Kate Yoshida (@KateYoshida) Video Illustrator: Ever Salazar (@eversalazar) Video Director: Emily Elert (@eelert) Video Narrator: Emily Elert (@eelert) With Contributions From: Henry Reich, Alex Reich, Peter Reich Music by: Nathaniel \u003ca href='http://www.soundcloud.com/drschroeder' target='_blank' rel='nofollow'\u003eSchroeder\u003c/a\u003e ___________________________________________ References: Brennan, P. and Prum, R. (2015). Mechanisms and Evidence of Genital Coevolution: The Roles of Natural Selection,Mate Choice, and Sexual Conflict. 1-21. Cold Spring Harbor Perspectives in Biology. Retrieved \u003ca href='http://cshperspectives.cshlp.org/content/7/7/a017749.abstract' target='_blank' rel='nofollow'\u003efrom\u003c/a\u003e Brennan, P. (2013). Genital Evolution: Cock-a-Doodle-Don’t. Current Biology. R523-R525. Retrieved \u003ca href='http://www.sciencedirect.com/science/article/pii/S0960982213004430' target='_blank' rel='nofollow'\u003efrom\u003c/a\u003e Brennan, P., Birkhead, T., Zyskowski, K., van der Waagand, J., and Prum, R. (2008). Independent evolutionary reductions of the phallus in basal birds. Journal of Avian Biology, 39: 487-492. Retrieved \u003ca href='http://onlinelibrary.wiley.com/doi/10.1111/j.0908-8857.2008.04610.x/abstract.' target='_blank' rel='nofollow'\u003efrom\u003c/a\u003e Briskie, J. and Montgomerie, R. (1997). Sexual selection and the intromittent organ of birds. Journal of Avian Biology. 28: 73-86. Retrieved \u003ca href='https://www.jstor.org/stable/3677097?seq=1#page_scan_tab_contents' target='_blank' rel='nofollow'\u003efrom\u003c/a\u003e Herrera, A., Brennan, P., and Cohn, M. (2014). Development of Avian External Genitalia: Interspecific Differences and Sexual Differentiation of the Male and Female Phallus. Sexual Development. 9: 43-52. Retrieved \u003ca href='https://www.ncbi.nlm.nih.gov/pubmed/25011524.' target='_blank' rel='nofollow'\u003efrom\u003c/a\u003e Reinhold, K. (1998). Sex linkage among genes controlling sexually selected traits. Sexual Selection. 44:1-7. 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