Concealed ovulation

Human females have concealed ovulation or hidden estrus. Most female animals show distinctive signs when they are "in heat". These include swelling and redness of the genitalia in baboons and bonobos Pan paniscus, 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. It has been said that the extended estrus period of the bonobo (reproductive-age females are in heat for 75% of their menstrual cycle)^[1] has a similar effect to the lack of a "heat" in human females.^[2]

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.^[3][4] It has also been suggested that a woman's voice may become more attractive to males during this time.^[5] 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.^[6] One group of authors has theorized that concealed ovulation and menstruation were key factors in the development of symbolic culture in early human society.^[7]

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.^[8]

See also

• Female choice
• Menstrual cycle
• Mittelschmerz

References

1. ^ Lanting, Frans; Waal, F. B. M. de (1997). Bonobo: the forgotten ape. Berkeley: University of California Press. pp. 107. ISBN 0-520-20535-9. http://www.serpentfd.org/a/dewall1997.html. Retrieved 2007-09-05. 
2. ^ Stanford, Craig B. (March-April 2000). "The Brutal Ape vs. the Sexy Ape? The Make-Love-Not-War Ape". American Scientist 88 (2): 110. doi:10.1511/2000.2.110. http://www.americanscientist.org/template/AssetDetail/assetid/14721/page/2;jsessionid=baa9. Retrieved 2007-09-05. 
3. ^ S.C. Roberts, J. Havlicek, J. Flegr, M. Hruskova, A.C. Little, B.C. Jones, D.I. Perrett and M. Petrie (August 2004). "Female facial attractiveness increases during the fertile phase of the menstrual cycle". Proc.R.Soc.Lond.B (Suppl.) 271: S270–S272. doi:10.1098/rsbl.2004.0174. 
4. ^ Geoffrey Miller, Joshua M. Tybur and Brent D. Jordan (June 2007). "Ovulatory cycle effects on tip earnings by lap dancers: economic evidence for human estrus?" (PDF). Evolution and Human Behavior 28 (6): 375–381. doi:10.1016/j.evolhumbehav.2007.06.002. http://www.unm.edu/~gfmiller/cycle_effects_on_tips.pdf. Retrieved 2008-01-21. 
5. ^ Pipitone, R.; G . Gallup Jr (2008-05-18). "Women's voice attractiveness varies across the menstrual cycle". Evolution and Human Behavior 29 (4): 268–274. doi:10.1016/j.evolhumbehav.2008.02.001. 
6. ^ Susan B. Bullivant, Sarah A. Sellergren, Kathleen Stern, et al. (February 2004). "Women's sexual experience during the menstrual cycle: identification of the sexual phase by noninvasive measurement of luteinizing hormone". Journal of Sex Research 41 (1): 82–93. PMID 15216427. http://www.findarticles.com/p/articles/mi_m2372/is_1_41/ai_n6032944. 
7. ^ Chris Knight (1991). Blood relations: menstruation and the origins of culture. New Haven, Conn: Yale University Press. ISBN 0-300-04911-0. 
   Knight, Chris; Camilla Power & Ian Watts (1995). "The Human Symbolic Revolution: A Darwinian Account" (PDF). Cambridge Archaeological Journal 5 (1): 75–114. doi:10.1017/S0959774300001190. http://www.radicalanthropologygroup.org/pub_knight_power_watts_big.pdf. Retrieved 2006-12-13. 
8. ^ Motluk, Alison (2006-08-05). "The secret life of semen". New Scientist (2563). http://www.eurekalert.org/pub_releases/2006-08/ns-tsl080206.php. Retrieved 2008-06-28. 

Further reading

• Marlowe, F.W. (October 2004). "Is human ovulation concealed? Evidence from conception beliefs in a hunter-gatherer society" (PDF). Archives of Sexual Behavior 33 (5): 427–432. doi:10.1023/B:ASEB.0000037423.84026.1f. http://www.fas.harvard.edu/~hbe-lab/acrobatfiles/is%20ovulation%20concealed.pdf. Retrieved 2007-10-11. 
• Pawłowski, Bogusław (June 1999). "Loss of Oestrus and Concealed Ovulation in Human Evolution" (PDF). Current Anthropology 40 (3): 257–276. doi:10.1086/200017. http://www.zoologi.su.se/research/tullberg/papers/99-CA-40.pdf. Retrieved 2007-10-11. ^{[dead link]}
• Haselton, Martie G. (January 2007). "Ovulatory shifts in human female ornamentation: Near ovulation, women dress to impress" (PDF). Hormones and Behavior 51 (1): 40–45. doi:10.1016/j.yhbeh.2006.07.007. http://www.debralieberman.com/downloads/courses/650/haselton_et_al_2007.pdf. Retrieved 2008-01-21. ^{[dead link]}