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Sexual swelling

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This is an old revision of this page, as edited by Nd2242 (talk | contribs) at 19:23, 10 February 2016 (Added 2 sentences explaining group size, and the reasons for the swellings (i.e. encourages males who can protect future offspring and provide resources).). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Sexual swellings are enlarged areas of the perineal skin occurring in some female primates that vary in size over the course of the menstrual cycle.[1] In ovariectomized chimpanzees, estrogen stimulation can induce such tumescence and progesterone can inhibit it.[2] Studies of chimpanzees[1] and Barbary macaques[3] suggest that sexual swellings serve as honest advertising of female fertility and thereby encourage males to copulate when the probability of conception is highest. A study into wild white-handed gibbons showed that maximum swelling size and ovulation overlapped closely in 80% of menstrual cycles [4] Larger sexual swellings in female baboons, for example, signal greater reproductive value. Male baboons, as a result, are seen to prefer females with these larger sexual swellings, as Domb and Leah (2001) found that sexual swelling size was related to an earlier age of sexual maturation and was also associated with both increased numbers of offspring and improved survival rates therefore it is likely that mating with these females will increase their chances of producing surviving offspring.[5] Exaggerated female sexual swellings are most commonly found in primate species that live in large groups with multiple males. Through advertising their quality, females can mate with high quality males who are capable of defending their offspring from other males, and those who can offer greater material benefits.[6]

References

  1. ^ a b Deschner, T.; Heistermann, M.; Hodges, K.; Boesch, C. (2004). "Female sexual swelling size, timing of ovulation, and male behavior in wild West African chimpanzees". Hormones and Behavior. 46 (2): 204–215. doi:10.1016/j.yhbeh.2004.03.013. PMID 15256310.
  2. ^ Graham, C. E.; Collins, D. C.; Robinson, H.; Preedy, J. R. K. (1972). "Urinary Levels of Estrogens and Pregnanediol and Plasma Levels of Progesterone during the Menstrual Cycle of the Chimpanzee: Relationship to the Sexual Swelling". Endocrinology. 91 (1): 13–24. doi:10.1210/endo-91-1-13. PMID 4112628.
  3. ^ Brauch, K.; Pfefferle, D.; Hodges, K.; Möhle, U.; Fischer, J.; Heistermann, M. (2007). "Female sexual behavior and sexual swelling size as potential cues for males to discern the female fertile phase in free-ranging Barbary macaques (Macaca sylvanus) of Gibraltar". Hormones and Behavior. 52 (3): 375–383. doi:10.1016/j.yhbeh.2007.06.001. PMID 17644098.
  4. ^ Barelli, C., Heistermann, M., Boesch, C., & Reichard, U. H. (2007). Sexual swellings in wild white-handed gibbon females (Hylobates lar) indicate the probability of ovulation. Hormones and behavior, 51(2), 221-230.
  5. ^ Domb, Leah G.; Pagel, Mark. "Sexual swellings advertise female quality in wild baboons". Nature. 410 (6825): 204–206. doi:10.1038/35065597.
  6. ^ Thornhill, Randy; Gangestad, Steven W. (2008). The Evolutionary Biology of Human Female Sexuality. New York: Oxford University Press. pp. 103–105. ISBN 978-0-19-534098-3.
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