The Science of Sexual Orientation - Essay Example

The Science of Sexual Orientation due: . Introduction Sexual orientation had widely been described and accommodated within biological and psychological realms. However, a number of historical and anthropological studies try to establish a linkage between social orientation and the underlying social and cultural structures that define human persons (Wilson and Rahman 2005). This paper will critically outline factors that determine the development of sexual orientation. To achieve this, we shall analyze various kinds of scientific evidence that exist. Much of the analysis in this paper and my understanding of the subject will be formed by literature reviewed from evolutionary psychologists’, biologists’ or socio-biologists’ accounts about the development of varying sexual orientation(s) among humans. Sexual Orientation Sexual orientation can be defined the development of romantic or sexual desires to people of the same, opposite or more than one gender or sexes. This orientation involves sexual desires, practices, feelings, and identification (DAugelli et al., 2001). There are people with sexual orientation towards different sex, but other have it towards same sex. Gender identity is a complex relationship between gender and sex addressing to people’s familiarity with their way of self-expression in social categories (Laumann et al., 1994). Comments from an article published by the American Psychiatric Association (2011), the most common names used to categorize these attractions are homosexual, heterosexual, and bisexual. Asexuality commonly explained as the lack of sexual attraction towards either sexes or gender is at times included as the fourth category (Melby, 2005; Prause and Cyntia 2004; Rust, 2000). These categories are suppressed deeply in the nature of sexual identities (Savin-Williams, 2000). As per an article published by the American Psychological Association (2013), sexual identity is related to people’s senses of identity based on sexual attractions and their position in the society with others who also share similar attractions. Often, individuals tend to confuse sexual preference with sexual orientation. Psychological research creates a distinction between the two by establishing the degree of voluntarism exhibited from sexual preference and the scientific consensus demonstrated by the inability to decide one’s sexual orientation (Heuer, 2011; Frankowski, 2004; Garcia-Falgueras & Swaab, 2010; Vare & Terry 1998). The Science of Sexual Orientation Over that last few decades, research on the origins and existence of different sexual orientations has received much public attention from specialists in different fields of study and especially biologists who try to establish its link with genes. Among them is Simon Levay whose research was widely accepted by media outlets and received little critique from other scientists. He used autopsied brain material to measure the volumes occupied by different cell groups within the hypothalamus (LeVay, S. 1991). Reports from his research indicated that the third group of cell, INAH3 was averagely two times larger in males than in homosexual males or their counterparts’ females. No differences existed between INAH 1, 2 and four groups of cell. Therefore, sexual orientation was based on biological substratum. Corresponding evidence interpreted in Levays’ findings has been used widely to explain the close similarities between the homosexual male behaviors and female behaviors as compared to that of male behaviors. A number of studies establish the lack of consensus among scientists on the nature of development of sexual orientation (Melby, 2005; Diamond 2010). However, studies conducted by Frankowski (2004) establish that scientists link nature and nurture by explaining sexual orientation as a combination of environmental, hormonal and genetic factors. It is important to note that biologically based theories pointing out genetic and social factors are commonly used to explain the nature of sexual orientation in the contemporary world (Garcia-Falgueras and Swaab, 2010). Research has also demonstrated the existence of orientation ranging from attraction to the opposite sex to attraction to the same sex. No substantive evidence suggests the connection of parenting and early childhood experiences to sexual orientation (Garcia-Falgueras and Swaab 2010; Långström et al., 2010). The existence of these kinds or research poses major questions relating to the causes of sexual orientation that have not yet been established regardless of efforts by scientists from different specializations. This section will critically link sexual orientation to biological and environmental factors. Biological and Environmental Factors As discussed earlier, a number of studies link sexual orientation to biological determinants. However, no conclusive research has yielded results revealing any single determinant linking the two (Bearman and Bruckner 2002). Scientific hypothesis establishes linkage between genetic, hormonal and social factors as the main determinants of sexual orientation (Långström et al., 2010; Frankowski, 2004). The popularity of linking biological factors that involve genetic factors and early uterine development has significantly grown. Empirical studies conducted by Bailey and Pillard (1991) on twins revealed that 52% of identical brothers and 22% of fraternal twins had regular developmental patterns. Similar studies conducted by Bailey, Dunne and Martin (2000) reported difference in sexual behaviors development patterns by less than half. A different study conducted on eight twin studies revealed that identical twins shared more sexual orientation similarities that their counterparts thus there was no existence of any important genetic component (Hershberger 2001). Similar results were shared by Bearman and Brückner (2002) who found little-supporting evidence linking any existing sexual developmental similarities between the set of twins and refuted any possible reliant genetic influence of social context. Other studies established existing links between same-sex behavior, heritable factors and environmental sources (individual-specific variables including sexual and prenatal experiences). On the other hand, variables that were shared in the environment such as society and family had a weak but significant developmental influence. It was also established that women statistics signified weak heredity influence trend as compared to their counterparts. On the contrary, men were not affected by shared environmental variables (Långström et al., 2010). These studies establish a link separating male and female sexual development. Chromosomal studies linked to sexual orientation reveal the existence of a number of genetic contributing factors linked to the genome. Findings published by Hamer et al. (1993) uncover the existence of more maternal gay uncles and cousins as compared to paternal ones. The results of this study were shared years later in a piece of research conducted by Sanders and colleagues. From their sample, 13 percent maternal gay uncles of brothers were homosexual compared to 6 percent on the paternal side (mentioned in Drabant et al. 2012). Similar studies yielded highly significant maternal connections that duplicate Sanders’ results (Hu et al. 1995; Mustanski et al. 2005). More research studies signify that a number of chromosomal variances are responsible for causing masculinity in women and feminism in men (Levay, 2011). Zietsch and her colleagues suggest that genes that cause men to appear more feminine in terms of looks, appearances and behaviors are similar to those that make women adopt masculine attributes. In addition, these genes exhibit reproductive advantages that may not necessarily push individuals possessing them to homosexuality (Zietsch et al. 1998). A number of sources link environmental factors to sexual orientation. No substantial evidence exists to suggest events such as sexual abuse, pre and post natal childhood experiences and sexual abuse among other environmental variables indeed affect sexual orientation (Garcia-Falgueras and Swaab 2010). Nevertheless, experimental studies confirm that parenting attitudes are more likely to affect the parent-child sexual orientation behaviors (Davidson & Moore, 2001; Golombok & Tasker, 1996). Animal Studies The practice of same-sex behaviors in animals has appealed both scientists and non-scientists. Contradictions have existed on the scientific selection of non-reproductive animals. However, very little has been established about the evolutionary consequences presented (Levan, K.E. et al. 2008; Santtila, P. et al. 2009). The nature of the relationships still remains a mystery as unproved information reflects such relationships as life-long pairing while others define them as mere sexual attractions. Nature has provided an impressive variety of same-sex behaviors in animals such as same-sex bonding and copulation among a wide range of mammals, amphibians, reptiles, birds, and insects. The existence of these behaviors is mostly undervalued due to the scientific observation that all monomorphic sexual pairs engaging in sexual contact are of opposite sexes (Bailey and Zuk, 2009). Empirical sexual orientation research has been conducted on numerous animal model systems. Contemporary studies conducted by Pavlov and Goodwin (2013) on Drosophila melanogaster, a common fruit fly revealed that sexual differentiation of the brain and behaviors are well established in both male and females. Therefore, the fruit fly had established a biologically controlled biological courtship model. Mammalian studies conducted by removing a single reproductive linked gene from a female rat revealed exhibition of masculine sexual behavior towards female urine. Kin selection of animal studies where non-reproductive sections of insects population work hard to ensure that the reproductive population has a comfortable life has also been used to explain the nature of evolutionary adaptive models of homosexual behaviors (Mayr, 1982). A representative sample of same-sex behavior across non-human taxa revealed that male African bat bugs traumatically inseminated both males and females. Additionally, they possessed genital structures that reduced negative traumatic effects of insemination (Reinhardt, K. et al., 2007). Female Bonobos spend most of their time engaging in same-sex behaviors such as rubbing of genitals till they reached orgasm while the males kissed other male counterparts. These behaviors eased social tension and facilitated reconciliation among members (Fruth and Hohmann, 2006). Whenever presented with an option and chance to engage in sexual behavior with an opposite sex, people with identical sex preferences mostly choose to engage in sexual behaviors. Same sexual behaviors are flexibly deployed in a number of circumstances among them, social bonding, mediation of internal conflicts, breeding and alternative reproduction tactics. After adapting to the social condition, established behaviors become selective forces capable of shaping a species’ social behaviors, physiology, morphology; as well as life history. Evolution Scientifically, it is established that heterosexual intercourse remains to be the main controlled mode of reproduction that supports reproductive health. Therefore, homosexual, asexual and other practices that reduce heterosexual intercourse significantly decrease successful reproduction and thus affect the evolution process. In line with the Darwinian model of survival for the fittest and natural selection, it is wise to assume that homosexuality would significantly reduce its frequency. Based on this, several scientists have developed theories to explain the major contradiction. A number of scholars suggest that homosexuality is an adaptive style of life that is not obvious (Maclntyre and Estep, 1993). These studies base their explanation to the gene that causes sickle cell anemia. Comparisons are made to the existence of a pair of these genes in a body that may present malaria resistance as a lesser anemia form. Thus it takes the heterozygous advantage (Mayr, 1982). Evolutionary theories contextualize the “maternal gay uncle and cousins” hypothesis as people without children increasing the prevalence of their future familial genes through the provision of material and psychological resources and support to the offspring’s of their close relatives. In so doing, they would be conforming to the theory of kin selection that explains human acts that appeared to be maladaptive, a concept that has been supported by several scholars (Mayr, 1982). A study conducted in 2008 reveals that no considerable evidence suggesting the genetic attachment of human sexual orientation. It was not established how the homosexuality trend that basically lowered reproductive accomplishment was maintained in a high-frequency population. Therefore, genetic variances affecting homosexual’s reproductive achievements could present advantages in carrier heterosexuals. It is possible that genetic variances in homosexuals could present the mating advantage among heterosexuals. This pathway could possibly explain an evolutionary theory and the maintenance of homosexuals in the population. Similarly, men exhibiting female traits become more attractive to fellow females and are thus likely to mate (Zietsch et al. 2008). The same study further outlined the impossibility of ruling out non-genetic variances among the hetero and homo-hetero twin pairs having more partners. It was established that most probably social factors affected the latter twin who most probably sought a more sexual partners (Gringas and Chen, 2001). This hypothesis was strongly supported by a study that sought to intensify birth rate in female matrilineal families of gay men (Camperio-Ciani, Corna, & Capiluppi, 2004). Conclusion Biological studies conducted on twins established that a number of environmental and individual-specific variables affected the male and female sexual orientation differently, and thus creating differences in their sexual development. However, even with the existence of a number of studies conducted to establish the major causes of sexual orientation, empirical research maintains that sexual orientation is reliant on a combination of environmental, genetic and hormonal influences as no single controlling cause has been identified. References Bailey, M., Dunne, P. & Martin, G. (2000). "Genetic and environmental influences on sexual orientation and its correlates in an Australian twin sample". J Pers Soc Psychol78 (3): 524–36. doi:10.1037/0022-3514.78.3.524 Bailey, M. & Pillard, C. (1991). "A Genetic Study of Male Sexual Orientation". Archives of General Psychiatry 48 (12): 1089–96. doi:10.1001/archpsyc.1991.01810360053008 Bailey, N. & Zuk, M. (2009).Same-sex sexual behavior and evolution. Journal of Evolution of Human Behavior, 30: 58–65, doi:10.1016/j.tree.2009.03.014. Bearman, S. & Bruckner, H. (2002) Opposite-sex twins and adolescent same-sex attraction. American Journal of Sociology 107, 1179–1205. Bearman, S. & Bruckner, H. (2002) Opposite-sex twins and adolescent same-sex attraction. American Journal of Sociology.107, 1179–1205. Camperio-Ciani, A., Corna, F. & Capiluppi, C. ( 2004). "Evidence for maternally inherited factors favouring male homosexuality and promoting female fecundity". Proc. Biol. Sci. 271 (1554): 2217–21. doi:10.1098/rspb.2004.2872  DAugelli, et al.(2001). "Suicidality patterns and sexual orientation-related factors among lesbian, gay, and bisexual youths". Suicide and Life-Threatening Behavior 31 (3): 250–264. doi:10.1521/suli.31.3.250.24246 Davidson, J., & Moore. N., (2001).Speaking of Sexuality: Interdisciplinary Readings, Los Angeles, Calif.: Roxbury Publishing. Diamond, M. (2010). Sexual orientation and gender identity. In Weiner IB, Craighead EW eds. The Corsini Encyclopedia of Psychology, Volume 4. p. 1578. John Wiley and Sons, Drabant, E., Kiefer, A., Eriksson, N., Mountain, J., Francke, U., Tung, J. & Hinds, D. (2012).Genome-Wide Association Study of Sexual Orientation in a Large, Web-based Cohort. 23 and Me Inc, Mountain View, CA Frankowski, B. (2004). American Academy of Pediatrics Committee on Adolescence. "Sexual orientation and adolescents". Pediatrics 113 (6): 1827–32. doi:10.1542/peds.113.6.1827 Fruth, B. & Hohmann, G. (2006) Social grease for females? Same-sex genital contacts in wild bonobos. Homosexual Behaviour in Animals. Sommer, V. & Vasey, L. (eds), pp. 294–315, Cambridge University Press Garcia-Falgueras, A. & Swaab, F. (2010). Sexual Hormones and the Brain: An Essential Alliance for Sexual Identity and Sexual Orientation, in Endocrine Development. Pediatric Neuroendocrinology vol. 17: 22–35  Gringas, P. & Chen, W. (2001). "Mechanisms for difference in monozygous twins". Early Human Development 64 (2): 105–117. doi:10.1016/S0378-3782(01)00171-2 Golombok, S. & Tasker, F. (1996). Do Parents Influence the Sexual Orientation of Their Children? Findings From a Longitudinal Study of Lesbian Families, in Developmental Psychology (American Psychological Association, 32: 3–11) Hamer, H., Hu, S., Magnuson, L., Hu N, & Pattatucci, M. (1993). "A linkage between DNA markers on the X chromosome and male sexual orientation". Science 261 (5119): 321–7. doi:10.1126/science.8332896 Hershberger, L. (2001). Biological Factors in the Development of Sexual Orientation. D’Augelli, A. and Charlotte, P. (Eds). Lesbian, Gay, and Bisexual Identities and Youth: Psychological Perspectives. Oxford, New York: Oxford University Press.  Heuer, G. (2011). Sexual revolutions: psychoanalysis, history and the father. Taylor & Francis. Hu, S. et al. (1995). "Linkage between sexual orientation and chromosome Xq28 in males but not in females". National Genetics. 11 (3): 248–56. doi:10.1038/ng1195-248 Långström, N., Rahman Q., Carlström, E., & Lichtenstein, P. (2010). "Genetic and Environmental Effects on Same-sex Sexual Behavior: A Population Study of Twins in Sweden". Archives of Sexual Behavior 39 (1): 75–80. doi:10.1007/s10508-008-9386-1 Laumann, et al. (1994). The Social Organization of Sexuality. The University of Chicago Press LeVay, S. (2011). Gay, Straight, and the reason why. The science of sexual orientation. Oxford University Press. pp. 45–71; 129–156 LeVay, S. (1991). "A difference in hypothalamic structure between heterosexual and homosexual men". Science 253 (5023): 1034–7.doi:10.1126/science.1887219 Levan, E. et al. (2008) Testing multiple hypotheses for the maintenance of male homosexual copulatory behaviour in flour beetles. Journal of Evolution Biology, 22: 60–70 MacIntyre F, Estep KW (1993). "Sperm competition and the persistence of genes for male homosexuality". BioSystems 31 (2–3): 223–33. doi:10.1016/0303-2647(93)90051-D Mayr, E. (1982). The Growth of Biological Thought: Diversity, Evolution, and Inheritance. Cambridge: Harvard University Press. Melby, T. (2005). "Asexuality gets more attention, but is it a sexual orientation?". Contemporary Sexuality 39 (11): 1, 4–5. Mustanski, S., Dupree, G., Nievergelt, M., Bocklandt, S., Schork, J., Hamer, H., (2005). "A genomewide scan of male sexual orientation" (PDF). Human Genetics. 116 (4): 272–8. doi:10.1007/s00439-004-1241-4 Park, D., Choi, D., Lee, J., Lim, S. & Park, C. (2010). "Male-like sexual behavior of female mouse lacking fucose mutarotase". BMC Genetics 11: 62. doi:10.1186/1471-2156-11-6 Pavlou, J. and Goodwin, F. (2013). "Courtship behavior in Drosophila melanogaster: towards a courtship connectome". Current Opinion in Neurobiology 23(1): 76–83. doi:10.1016/j.conb.2012.09.002 Prause, N., & Cynthia G. (2004). "Asexuality: Classification and Characterization". Archives of Sexual Behavior 36 (3): 341–356.doi:10.1007/s10508-006-9142-3. Reinhardt, K. et al., (2007) Female-limited polymorphism in the copulatory organ of a traumatically inseminating insect. American Nature, 170, 931–935 Rust, P., (2000). Bisexuality in the United States: A Social Science Reader. Columbia University Press. Santtila, P. et al. (2009) Testing Miller’s theory of alleles preventing androgenization as an evolutionary explanation for the genetic predisposition for male homosexuality. Savin-Williams, R. (2006). "Whos Gay? Does it Matter?". Current Directions in Psychological Sciences 15: 40–44. doi:10.1111/j.0963-7214.2006.00403.x "Sexual orientation, homosexuality and bisexuality". American Psychological Association. (2013). Retrieved December 5, 2014, from http://www.apa.org/helpcenter/sexual-orientation.aspx  "Sexual Orientation". American Psychiatric Association. (2011) Retrieved December 5, 2014, from http://www.psychiatry.org/mental-health/people/lgbt-sexual-orientation Vare, W. & Terry N (1998). "Understanding Gay and Lesbian Youth: Sticks, Stones and Silence." Cleaning House 71.6: 327-331: Wilson, G.D., & Rahman, Q. (2005). Born Gay: The Biology of Sex Orientation. London: Peter Owen Publishers. Zietsch, B., Morley, K., Shekar, S., Verweij, K., Keller, M., Macgregor, S., Wright, M., Bailey, J. & Martin, N. (2008). Genetic factors predisposing to homosexuality may increase mating success in heterosexuals, 29 (6): 424 – 433. doi: http://dx.doi.org/10.1016/j.evolhumbehav.2008.07.002 Read More