Concealed ovulation 764891 222263013 2008-06-28T11:48:50Z Lyrl 408908 Specify human Human females have '''concealed ovulation''' or '''hidden estrus'''. Most [[female]] animals show distinctive signs when they are "[[estrous|in heat]]". These include swelling and redness of the genitalia in [[baboons]] and [[bonobos]], [[pheromone]] release in the feline family, etc. By comparison, [[human]] females have few external signs of [[fertility]]. It is difficult to tell, by means of external signs only, whether or not a woman is near [[ovulation]]. Humans are the only [[mammal]] to lack obvious, visible manifestations of fertility, although some argue that the extended [[estrus]] period of the [[bonobo]] (reproductive-age females are in heat for 75% of their menstrual cycle)<!-- --><ref>{{cite book |author=Lanting, Frans; Waal, F. B. M. de |title=Bonobo: the forgotten ape |publisher=University of California Press |location=Berkeley |year=1997 |pages=p.107 |isbn=0-520-20535-9 |url=http://www.serpentfd.org/a/dewall1997.html |accessdate=2007-09-05 }}</ref><!-- --> has a similar effect to the lack of a "heat" in human females.<!-- --><ref>{{cite journal | last = Stanford | first = Craig B. | title = The Brutal Ape vs. the Sexy Ape? The Make-Love-Not-War Ape | journal = American Scientist | volume = 88 | issue = 2 | pages = 110 | date = March-April 2000 | url = http://www.americanscientist.org/template/AssetDetail/assetid/14721/page/2;jsessionid=baa9 | doi = 10.1511/2000.2.110 | accessdate = 2007-09-05 }}</ref> While women can be taught to recognize their own level of fertility ([[fertility awareness]]), whether men can detect fertility in women is highly debated. On one hand, several small studies have found that fertile women (compared to women in infertile portions of the menstrual cycle or on hormonal contraception) appear more attractive.<!-- --><ref>{{cite journal | author=S.C. Roberts, J. Havlicek, J. Flegr, M. Hruskova, A.C. Little, B.C. Jones, D.I. Perrett and M. Petrie | title = Female facial attractiveness increases during the fertile phase of the menstrual cycle | journal = Proc.R.Soc.Lond.B (Suppl.) | volume = 271 | pages = S270–S272 | date = August 2004 | doi = 10.1098/rsbl.2004.0174}}</ref><!-- --><ref>{{cite journal | author = Geoffrey Miller, Joshua M. Tybur and Brent D. Jordan | title = Ovulatory cycle effects on tip earnings by lap dancers: economic evidence for human estrus? | journal = Evolution and Human Behavior | volume = 28 | issue = 6 | pages = pp. 375–381 | date = June 2007 | url = http://www.unm.edu/~gfmiller/cycle_effects_on_tips.pdf | accessdate = 2008-01-21 | doi = 10.1016/j.evolhumbehav.2007.06.002 }}</ref> <!-- -->On the other hand, two small studies of monogamous couples found that women initiated sex significantly more frequently when fertile, but male-initiated sex occurred at a constant rate in all phases of the menstrual cycle.<!-- --><ref>{{cite journal | author= Susan B. Bullivant, Sarah A. Sellergren, Kathleen Stern, et al | title= Women's sexual experience during the menstrual cycle: identification of the sexual phase by noninvasive measurement of luteinizing hormone | journal=Journal of Sex Research | year=February 2004 | volume=41 | issue=1 | pages=82–93 | url=http://www.findarticles.com/p/articles/mi_m2372/is_1_41/ai_n6032944 | pmid=15216427}}</ref> <!-- -->One group of authors has theorized that concealed ovulation and menstruation were key factors in the development of [[symbolic culture]] in early human society.<!-- --><ref>{{cite book | author = Chris Knight | title = Blood relations: menstruation and the origins of culture | publisher = Yale University Press | location = New Haven, Conn | year = 1991 | id = ISBN 0-300-04911-0}}<br><!-- -->{{cite journal | last = Knight | first = Chris | coauthors = Camilla Power & Ian Watts | title = The Human Symbolic Revolution: A Darwinian Account | journal = Cambridge Archaeological Journal | volume = 5 | issue = 1 | pages = 75–114 | date = 1995 | url = http://www.radicalanthropologygroup.org/pub_knight_power_watts_big.pdf | accessdate = 2006-12-13 }}</ref> In 2008, researchers announced the discovery of hormones related to ovulation in human semen. They theorized that [[follicle stimulating hormone]], [[luteinising hormone]], and [[estradiol]] may encourage ovulation in women exposed to semen. These hormones are not found in the semen of chimpanzees, suggesting that this phenomenon may be a male counter-strategy to concealed ovulation in human females. Other researchers are skeptical that the low levels of hormones found in semen could have any effect on ovulation.<!-- --><ref>{{cite journal | last = Motluk | first = Alison | title = The secret life of semen | journal = [http://www.newscientist.com New Scientist] | issue = 2563 | date = 2006-08-05 | url = http://www.eurekalert.org/pub_releases/2006-08/ns-tsl080206.php | accessdate = 2008-06-28}}</ref> ==See also== *[[Menstrual cycle]] *[[Mittelschmerz]] ==References== <references /> ==Further reading== * {{cite journal | last = Marlowe | first = F.W. | title = Is human ovulation concealed? Evidence from conception beliefs in a hunter-gatherer society: the Hadza of Tanzania | journal = Archives of Sexual Behavior | volume = 33 | issue = 5 | pages = pp. 427–432 | date = October 2004 | url = http://www.fas.harvard.edu/~hbe-lab/acrobatfiles/is%20ovulation%20concealed.pdf | accessdate = 2007-10-11 | doi = 10.1023/B:ASEB.0000037423.84026.1f }} * {{cite journal | last = Pawłowski | first = Bogusław | title = Loss of Oestrus and Concealed Ovulation in Human Evolution | journal = Current Anthropology | volume = 40 | issue = 3 | pages = pp. 257–276 | date = June 1999 | url = http://www.zoologi.su.se/research/tullberg/papers/99-CA-40.pdf | accessdate = 2007-10-11 | doi = 10.1086/200017 }} * {{cite journal | last = Haselton | first = Martie G. | title = Ovulatory shifts in human female ornamentation: Near ovulation, women dress to impress | journal = Hormones and Behavior | volume = 51 | issue = 1 | pages = pp. 40–45 | date = January 2007 | url = http://www.debralieberman.com/downloads/courses/650/haselton_et_al_2007.pdf | accessdate = 2008-01-21 | doi = 10.1016/j.yhbeh.2006.07.007 }} [[Category:Menstruation]] [[Category:Sexual conflict]] [[Category:Sexual selection]]