Why Do We Have More Boys Than Girls?

2014-09-04 59,481 2,543 4,836,913 YouTube

Subscribe to MinuteEarth! - http://www.youtube.com/user/minuteearth?sub_confirmation=1 And support us on Patreon: https://goo.gl/ZVgLQZ ________________________ Created by Henry Reich Production and Writing Team: Alex Reich, Peter Reich, Emily Elert, Ever Salazar, Kate Yoshida, and Henry Reich Music by Nathaniel Schroeder: http://www.soundcloud.com/drschroeder Narrated by: Emily Elert ________________________ Free iTunes podcasts of MinuteEarth! - https://goo.gl/sfwS6n Facebook - http://facebook.com/minuteearth Twitter - http://twitter.com/MinuteEarth MinuteEarth provides an energetic and entertaining view of trends in earth's environment -- in just a few minutes! ________________________ References Cameron, E.Z. (2004). Facultative adjustment of mammalian sex ratios in support of the Trivers-Willard hypothesis: evidence for a mechanism. Proceedings of the Royal Society of London Series B 271:1723–1728. http://rspb.royalsocietypublishing.org/content/271/1549/1723 Chahnazarian, A. (1988). Determinants of the sex ratio at birth: Review of recent literature. Social Biology 35 (3–4): 214–235. http://www.tandfonline.com/doi/abs/10.1080/19485565.1988.9988703?journalCode=hsbi20#.U-5oSPldWRM Coale, A.J. (1991). Excess female mortality and the balance of the sexes in the population: An estimate of the number of "missing females." Population and Development Review 17(3): 517-523.http://www.jstor.org/discover/10.2307/1971953?uid=3739824&uid=2&uid=4&uid=3739256&sid=21104121507601 Clutton-Brock, T. H., Albon, S. D., and Guinness, F. E. (1986). Great expectations: dominance, breeding success and offspring sex ratios in red deer. Animal Behavior 34: 460-471. http://www.kora.ch/malme/05_library/5_1_publications/C/Clutton-Brock_et_al_1986_Dominance_breeding_success_and_offspring_sex_ratios_in_red_deer.pdf Kalben B. (2000). Why men die younger: causes of mortality differences by sex. North American Actuarial Journal 4(4): 83–111. https://www.soa.org/news-and-publications/publications/other-publications/monographs/m-li01-1-toc.aspx Schnettler, S. (2013). Revisiting a Sample of U.S. Billionaires: How Sample Selection and Timing of Maternal Condition Influence Findings on the Trivers-Willard Effect. PLoS ONE 8(2): e57446. http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0057446 Song, S. (2012). Does famine influence sex ratio at birth? Evidence from the 1959–1961 Great Leap Forward Famine in China. Proceedings of the Royal Society B 279(1739):2883-2890. http://rspb.royalsocietypublishing.org/content/early/2012/03/16/rspb.2012.0320.full Thogerson C.M., Brady, C.M., Howard, R.D., Mason, G.J., Pajor, E.A., Vicino, G.A., and Garner, J.P. (2013) Winning the genetic lottery: biasing birth sex ratio results in more grandchildren. PLoS One 8(7):e67867. http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0067867 Trivers, R.L., and Willard, D.E. (1973). Natural selection of parental ability to vary the sex ratio of offspring. Science 179: 90-92. http://www.sciencemag.org/content/179/4068/90.abstract Photo credits: Elephant Seal 1 Photo by: Roy Mangersnes http://roywildphoto.blogspot.com/2008/11/elephant-seals.html Elephant Seal 2 Photo by: Mike Baird https://www.flickr.com/photos/mikebaird/11830159673/ White tailed deer Photo by: Public Domain http://en.wikipedia.org/wiki/File:White-tailed_deer.jpg Key Deer Photo by: IanarÈ SÈvi http://commons.wikimedia.org/wiki/File:Odocoileus_virginianus_clavium_fawn.jpg Male Lion Photo by: Wikimedia user Robek http://commons.wikimedia.org/wiki/File:Pair_of_lions_v2.jpg Baby Lion Photo by: Flickr user fortherock https://www.flickr.com/photos/fortherock/3897872187/ Brad Pitt Photo by: Foreign and Commonwealth Office http://www.flickr.com/photos/foreignoffice/14217374639/ Kids Photo by: Barbara Hobbs http://commons.wikimedia.org/wiki/File:Upclose_of_kids_-_Alberti_Flea_Circus,_MerleFest_2013.jpg