Within human culture, the hymen has great significance for its perceived correlation to female sexual status. For many cultures, the presence of an intact hymen before marriage suggests purity and cleanliness. Outside of weddings and marriage, hymens have also had cultural relevance as the word âhysteriaâ is derived from womb-fury, which was associated with the hymen*. Over time, the role of the hymen within culture has changed from being a cause of madness to, in more scientifically-minded societies, being seen as a biological part of the human female body. And so, too, with these shifting perceptions, the human comprehension of the hymen has changed as well. Even though cultural perspectives on the presence and function of the hymen have changed, little is understood in which circumstances the hymen may have been sexually selected. Some scholars posit cultural practices as a method for selection, while others suggest a more morphologically related explanation based on evolutionary responses to the environment. It is thought that because the hymen offers a barrier of protection in the external vaginal opening, through evolving human cultural practices, it enhances a womanâs individual fitness. The sexual selection of the human hymen is related to hygienic purposes in order to reduce infertility and has been supported indirectly through cultural practices.
Hymen: the stigmatized tissue
Among the many tissues within the human body, few are more stigmatized than the hymen. This is largely in part due to the human cultural perceptions of the hymen as a measure of sexual status. And while the hymen is well known for the cultural perceptions, few are aware of the actual anatomical and physiological aspects. Commonly misconceived as a part of the internal vaginal canal, in reality, the hymen is not inside of the vagina at all. The hymen is a membrane-like tissue which is considered part of the external genitalia, whereas the internal vaginal orifice is partly covered by the labia majora. Although hymens are only present in the female sex, there are variations of the types that may naturally occur. Hymen morphological variation can range from crescent-shaped, ring-shaped, folded upon itself, banded across the opening, holed, or, without an opening within the hymen at all. Such cases are considered âimperforated hymensâ and only occur in 1 in 2,000 females (Kurman 2002). Variation exists in the types present within females and in the evolutionary morphology of its presence.
Although debated by scholars, it is thought some human females are not the only ones to be lacking a hymen. Throughout the Primate order, only two living species (other than humans) are known to have hymens: lemurs and chimpanzees (Cold & McGrath 1999). It is unclear what circumstances may have lead to the evolutionary reversion for the hymen to reappear because tissues tend to not preserve in the fossil record. In addition, we do not have clear physical evidence to distinguish whether the hymen is a retained ancestral trait, or it arose three times within lemurs, chimpanzees, and humans as a homoplasy. However, there are multiple theories which support the idea of the hymen as a retained ancestral trait in response to ecological conditions where it would have been beneficial to retain a tissue on the external genitalia.
The Evolutionary Theories
An aquatic ape? (Photo by: Barry Bland via DailyMail)
One of the methods scholars posit as a reason for the hymen to be selected for is in relation to our evolutionary history. In one of the more contested human evolutionary theories, the aquatic ape theory, it is thought the hymen was selected for as a response to the ecological conditions in which hominid ancestors were living. In this theory, hominids spent a substantial amount of time in waters due to competition for food resources (Hardy 1960). Over time, the hominid ancestors waded further into waters, as competition grew less fierce. In order to support this claim, Hardy draws on the loss of hair from hominoid ancestors to present modern human as evidence by paralleling them to numerous other aquatic mammals that tend to lack hair. In addition to the hair loss, the presence of the hymen was thought to be an adaptation to the new aquatic environment.
Within the new habitat, hominids were more at risk to microbes rarely encountered on land. Morgan hypothesizes that the hymen evolved as an independent adaptation to avoid vaginal infections caused by microbes within the aquatic environment (Morgan 1972). As hominids walked upright more frequently within the aquatic habitat, the likelihood of contracting vaginal infections increased. These vaginal infections were considered to cause infertility and as a result, reduce reproductive success (Hobday et al. 1997). Therefore, females that possessed these tissues to ward off infections were more likely to be reproductively successful and pass on the adaptation to offspring. After enough time passed, the tissue remained in hominids as an apomorphy.
While this is possible, many scholars refute the possibility of the aquatic ape theory. In direct reference to the hymen, the aquatic ape theory fails to take into account the fact the hymen only offers limited protection for the vagina due to the fact it does not cover the entirety of the genitals.  In defense of the aquatic ape theory, some scholars believe that even partial coverage is more beneficial than none at all (Morgan 1972). However, this does not take into account the likelihood in which these infections would persist in female populations. Furthermore, this theory also does not recognize the probability of the hymen tearing from sexual intercourse or other methods, thus, further reducing the chances in which the hymen would offer protection. Therefore, evidence seems to deviate from the role of the aquatic ape theoryâs ecological selection.
Another alternative suggests a different source for the hymenâs function. In a more recent hypothesis, Hobday et al. postulate that the hymen is an embryological structure (leftover from the conjunction of the sino-vaginal bulb and muellerian ducts) retained into juvenility but also serving as a barrier against infectious microbes (1997; Raveenthiran 2009). As humans tend to be more altricial and weaker at birth than other primate ancestors, the necessity for having further protection was naturally selected for into childhood and adolescence. Although it has yet to be determined, given the change to an upright posture and a reduction into the size of the birth canal, it is not likely the function of the human hymen is necessarily the same as the one in lemurs and chimpanzees (Hobday et al. 1997). Currently, it is unclear when this trait may have evolved, as it is unlikely to be a trait shared with chimpanzees given the morphological changes from chimpanzees to humans. In this context, this suggests the idea that the hymen evolved three times. The hymen in Hobdayâs exaptation theory serves as a homoplasy, and it is postulated this evolutionary adaptation may have benefitted humans for more hygienic reasons, which may not have been necessary in primate ancestors.
A pair of ring-tailed lemurs (Lemur catta) grooming. (Photo by: Mike Powles via ARKive.org)
Particularly because human infants are altricial at birth and unable to groom themselves, hygiene is an important factor when considering the health of an infant. Even though it is possible for the mother to groom, it is impossible for her to remove microscopic foreign infectious agents from the vaginal area. Having a membrane-like tissue to prevent foreign materials, such as fecal matter and other such substances, would provide protection to infants during this vulnerable time (Hobday et al. 1997). Furthermore, it is assumed that this would be naturally selected for, as variations of hymens exist. Thus, hymens that offer more protection would be more likely to pass on their genes to offspring, as fewer infections would occur in the very young, leading to fewer cases of infertility.
The phenotypic variation expressed in hymens can provide scholars greater insight into the legitimacy of claims in that the hymen might reduce infertility. One of the ways in which this hypothesis can be examined further is making the comparison between intact hymens and imperforated hymens. While imperforated hymens are rarer in the general population, they have subsisted nonetheless. Currently, scholars believe that the transmission of the imperforated hymen is a dominant trait (Sterling et al. 2000). As such, the phenotypic trait would be more likely to occur in the general population over time. The imperforated hymen can be reversed through surgical intervention, but without doing so, can lead to a significant delay in menarche and puberty, abdominal pain, urinary accumulations (which may lead to infections), smegma blockage, and prevent menstrual blood from escaping; all of which, over time, could lead to increased mortality risk (Posner & Spandorfer 2005). Given that the chance of mortality increases if build up of smegma and other accumulations increase over time without intervention, as imperforated hymens are a health risk, this lends credibility to hymens being a naturally selected trait. While having too thick of a hymen might lead to some infections, having a less thick and breakable hymen might function as a filter for infectious microbes.
This exaptation hypothesis, much like the aquatic ape theory, tends to receive criticism for its explanation of the hymenâs function. For instance, following the breaking of the hymen through loss of virginity or other physical methods, females would be likely to lose the protection from microbial agents (Maul 2007). While this may be the case, Maul fails to take into account that it is possible for a female to have offspring after the first sexual intercourse assuming she has reached menarche. If she is able to have viable offspring from her first sexual encounter, it is not as critical for her body to ward off against infections. Her female offspring would also be likely to carry the trait of having a hymen which would offer the same protections. Furthermore, Maul also does not recognize the fact that adolescents would be old enough to begin to clean the vagina on their own, thus, offering another source of defense against microbial infections.
The other substantial criticism of Hobday et al.âs hymen exaptation hypothesis is that the hymen is not necessarily a beneficial trait when considering sexual selection pressures. If the hymen is selected to be occlusive, it may cause difficulty for the first intercourse and subsequent coituses if the hymen is too obstructive to be penetrated (Cox 1995). In the case intercourse provides to be a difficult and painful experience for both individuals, intercourse might occur less frequently. Therefore, the chances of passing on the phenotype of an occlusive hymen are reduced in this situation.  This criticism is weak, at best, as it does not regard the fact it reduces reproductive fitness as females are less likely to have intercourse due to painful coitus; thus, limiting the number of offspring produced. In addition, it also fails to take into account the significance of human cultural values on virginity and the status of the hymen.
The Cultural Experience
           Across multiple human cultures and societies, the presence of the hymen is an important trait within women. For centuries, within various mythologies and religions, cultural practices, and human perceptions, the hymen has had a significant role in the female status. In one of the more notorious examples, the Islamic ideology of men receiving 72 virgins in the wake of suicide-killings is compelling enough to shift the incentive from living to the desire for death (Franck et al. 2005). As the 72 virgins symbolize indefinite personal gain, the loss of life becomes inconsequential as the future gain of these women with present hymens outweighs the current experience of life. On the contrary, while these men gain incentive to take their lives for the women with virginal status, women who have been found to lose their virginal status prior to marriage are sometimes forced into these suicide-killing situations as a way of restoring honor to their families (Franck et al. 2005). In this ideology, men, regardless of having virginal status or not, are rewarded with women who maintain virginity, whereas, females are punished with death for not retaining theirs. Although this example is extreme, highly rare within the modern world, and exists within an oppressive, patriarchic paradigm, it highlights the significance of the presence of the intact hymen within a human society as a form of sexual selection pressure.
Throughout human history, the intact hymen has been regarded with reverence and general positivity. Many scholars support the idea of the human hymen been sexually selected via cultural methods for its symbolic importance in patrilineal societies. By having a partner who has an intact hymen, it is thought males can be certain of a female partnerâs sexual history (Hobday et al. 1997). Therefore, in the case of females becoming pregnant after first coitus, males can be more certain of their paternity in offspring. Conversely, this may serve as an indirect form of mate guarding as tearing the hymen might serve as a method of making females less attractive to other males, due to the uncertainty of paternity in any potential offspring (Buss 2006). In situations such as these where the intact hymen and virginal status are preferred traits, it is likely the hymen is a sexually selected attribute.
In some cultures, cherry pie is a very big deal. It's like a cool drink of water, or a sweet surprise.
Indirectly within multiple human cultures, the hymen may have been sexually selected as a trait which contributes to a femaleâs hygiene, but also as a valuable feature in attracting a mate. Sexual selection is defined as differential mating success among individuals within a population (Panhuis et al. 2001). As such, it is possible the hymen can serve as a sexually selected characteristic among females. Typically, sexual selection is expressed in males, but the presence of an intact hymen can serve as an unintentional form of intrasexual competition between females. Given that it might be more likely for men to choose virgin women as mates due to potentially being able to ascertain paternity status in offspring, the intact hymen might make it more likely for a female to be chosen as a mate (Maul 2007). Women who are chosen as mates are also thought to be more likely to have better access to resources that may increase individual fitness as she would have to spend less energy on procuring resources for herself. It must be noted, however, these factors are dependent upon the male preference for the intact hymen and perceived associated virginal status.
Although it is commonly thought to be the case that the tearing of the hymen equates to a loss of virgin status, new evidence has come forth to suggest otherwise. In recent years, data has come forth to suggest the presence of an intact hymen is no longer an entirely accurate depiction of virginal status. Among one of the many claims, a recent study linked 52% of a group of adolescent girls having an intact, non-disrupted hymen after first sexual intercourse (Adams et al. 2004). This finding suggests not only is it necessarily true the intact hymen correlates with a lack of previous sexual history, but even possibly a beneficial aspect for an intact hymen to exist after sexual intercourse. For instance, in the Yungar society of Australia, some women were brutally tortured, starved, and killed regularly if they lacked an intact hymen previous to marriage (Hobday et al. 1997). Accordingly, in some social contexts, having a more elasticized hymen to withstand penetration and tearing might be beneficial.  The presence of an intact hymen to persist may serve as a signal to males that she retains her chastity; thus, being able to continue living without stigmatization or persecution. As the hymen is still revered and important within some societies around the world as a signal of paternity certainty, other societies place less importance as evidence comes to light to suggest otherwise.
In addition to the fact in which having an intact hymen is no longer necessarily indicative of virginal status, recent technology has made it even more difficult to distinguish sexually active status. Through technological advancements have been made in feminine hygiene products, the use of tampons may actually be likely to tear the hymen as well as speculum examinations by gynecologists (Rogers & Stark 1998). Occurrences such as these are frequent in the westernized world, as many menstruating females can afford hygiene products. However, in areas of the world where females have limited access to hygiene products and routine gynecological examinations, this phenomenon is rarer (Farage et al. 2011). Recent surgical advances have also made it possible for some women to reconstruct the intact hymen, further adding to the complications of discerning sexually active females.
Surgeries which restore the intact hymen are often referred to as hymenorrhaphy or a hymenoplasty. In a hymenoplasty, the remnants of a torn hymen are stretched and stitched to the vaginal orifice (Prakash 2009). Within the surgery, the hymen is stretched out and essentially recreated from pre-existing tissue. In many countries, women will go to great lengths to get their hymen repaired to former status for reasons from fear of being thought of as unchaste (which might result in any consequence ranging from divorce to death) to cosmetic reasons to maintain a sexual partnerâs happiness (Prakash 2009). But in the context of sexual selection, the hymenoplasty could be considered as a deceptive signal. Much like the elasticized hymen which fails to tear even after sexual intercourse, the hymenoplasty can also serve as an indication to others that the female retains her virginal status.   The signal sent from this procedure can be used to deceive males into choosing a female as a mate, thus, serving as a strategy to outcompete other females without the presence of a hymen.
Though the function of the hymen is still widely debated among scholars, its presence can serve as a sexually selected trait that increases fitness in females. Females that live in cultures where males give preference to females with an intact hymen and perceived virginal status often receive benefits of better access to resources. In addition, it is hypothesized that these females are more likely to be reproductively successful for reasons related to an evolutionary function in which the hymen served as a barrier, preventing infectious microbes from entering the vaginal orifice. Therefore, females with an intact hymen until first coitus were thought to avoid infections which may have lead to infertility. As such, it was beneficial to choose women as mates who retained an intact hymen.  Despite recent studies suggesting the hymen is less elastic than previously thought, the importance of the hymen still remains in certain cultures around the world and still continues to thrive as a sexually selected trait.
Note: * = Initially, I was under the impression the term hysteria was linked to the hymen as it was once believed the hymen was part of the uterus. Not entirely true, however, hymens are linked to hysteria through the perceived womb fury. (More information on this can be found here)
References
Adams, J.A., Botash, A.S., & Kellogg, N. (2004). Differences in hymenal morphology between adolescent girls with and without a history of consensual sexual intercourse. Arch Pediatr Adolesc Med, 158(3): 280-285.
Buss, D.M. (2006). Strategies of human mating. Psych Topics, 2: 239-260.
Cold, C.J. & McGrath, K.A. (1999). Anatomy and Histology of the Penile and Clitoral Prepuce in Primates. In Denniston, G.C., Hodges, F.M., & Milos M.F. (Eds.), Male and Female Circumcision, (pp. 1-8), New York: Plenum Publishers.
Cox, G. (1995). De Virginibus Puerisque: the function of the human foreskin considered from an evolutionary perspective. Med Hypoth, 45: 617-621.
Farage, M.A., Miller, K.W., & Davis, A. (2011). Cultural aspects of menstruation and menstrual hygiene in adolescents. Exp Rev Obst Gyn, 6(2): 127-139.
Franck, R., Hillman, A.L., & Krausz, M. (2005). Public safety and the moral dilemma in the defense against terror. Def and Peace Econ, 16(5): 347-364.
Hardy, A. (17 March 1960). Was Man more aquatic in the past? New Scientist, 642-645.
Hobday, A.J., Haury, L., & Dayton, P.K. (1997). Function of the human hymen. Medical Hypotheses, 49, 171-173
Kurman, R.J. (2002). Blausteinâs Pathology of the Female Genital Tract (5th edition). New York: Springer-Verlag, 160.
Maul, A. (2007). An evolutionary interpretation of the significance of physical pain experienced by human females: defloration and childbirth pains. Med Hypoth, 69(2): 403-409.
Morgan, E. (1972). The Descent of Woman. New York: Stein and Day.
Panhuis, T.M., Butlin, R., Zuk, M., & Tregenza, T. (2001). Sexual selection and speciation. Trends Ecol Evol, 16(7): 364-371.
Posner, J.C. & Spandorfer, P.R. (2005). Early detection of imperforate hymen prevents morbidity from delays in diagnosis. Pediatrics, 115(4): 1008-1012.
Prakash, V. (2009). Hymenoplastyâhow to do. Indian J Surg, 71: 221-223.
Raveenthiran, V. (2009). Surgery of the hymen: from myth to modernization. Indian J Surg, 71: 224-226.
Rogers, D.J. & Stark, M. (1998). The hymen is not necessarily torn after sexual intercourse. Brit Med J, 317(7155): 414.
Sterling, J.R., Gray, M.R., Davis, A.J., Cowan, J.M., & Reindollar, R.H. (2000). Dominant transmission of imperforate hymen. Fert Steril, 74(6): 1241-1244.
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This is serious monkey business. 