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Sexual dimorphism and gender in humans
Essays on sexual dimorphism
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The Role of Estrogen in Sexual Differentiation
Most, if not all, species with two sexes exhibit sexually dimorphic behavior and physical characteristics. These dimorphisms can be attributed to differences in the brain, such as size or function of structure, and these brain structures can be affected by the hormones circulated throughout the organism. It has been held that the sexual dimorphisms rely only on the presence or absence of androgen, namely, testosterone, during the critical period of development for an organism; however, new research suggests that the presence of estrogen, specifically estradiol, has an active role in sexual differentiation.
Several sexual dimorphic structures in the brain have been observed in laboratory experiments. The corpus callosum in male rats is much larger than that in female rats, and this size difference is uncorrelated with total brain weight. These findings led many to investigate the relationship between human male and female corpus callosa. A paper published by de Lacoste-Utamsing and Holloway stated that the splenium of the callosum is larger in women than in men, but their finding has since been challenged by several reports stating that there exists no sexual dimorphism. Analysis done from 1982-1994 reveals a small difference of corpus callosum size in favor of males, but it is hypothesized that age, handedness, overall brain size and weight, and incorrect statistics were not taken into account. (3)
There has also been controversy in the research involving the brain region INAH-3 in humans. The heterosexual male INAH-3 is larger than that of heterosexual females; the INAH-3 in homosexual males is on the average smaller than that of heterosexual males and approximately the same size of heterosexual females. The general population has attempted to use this fact as an explanation of the biological basis of homosexuality, though the differences in structure may not be causally related to the sexual orientation of the man. Because we can only observe behaviors when doing experiments with lab animals, the data cannot firmly establish a basis for sexual orientation.
The traditional view on sexual differentiation is that organizational effects from hormones which occur during neonatal development are the master plan for the organisms sex and corresponding behaviors and characteristics. Exposure to androgen, namely, testosterone, would result in a male organism, while exposure to neither androgen nor estrogen would result in the default sex: female.
Characteristics resulting from organizational effects include formation of genitalia and traits such as aggression.
Psychologist, Richard A. Lippa, takes on the challenge of proving the concept that an individual’s idea of gender is derived from their brain, an issue otherwise recognized as “nature vs. nurture” in his book, Gender, Nature, and Nurture. Francis Galton, defines nature and nurture, as, “Nature is all that a man brings with himself into the world; nurture is every influence from without that affects him after birth.” Galton emphasizes the fact that nature produces the infant, with direct influences, determining both “growth of body and mind” (Galton) while nurture is an alteration of the environment for the comfort of the infant. Lippa establishes that each gender displays different levels of hormones, and physical capabilities, which will contribute to “nature.” An intriguing study conducted by Henry F. Harlow, whether the gender of a monkey can be determined, with or without the aid of parental influence. Regardless of whether the monkeys had a parent, the behaviors that they demonstrated in their natural environment were the same. The fundamental principle behind this is due to the fact that males were “influenced by the exposure to testosterone.” (122) As human beings, we vary in physical attributes, which subconsciously come into play when it comes to our preferences. This explains why the things that we do are gender
To begin with, gender must be examined at the basic level of science in regard to physical and biological development of humans. We all understand the physical differences between the male and female gender, but how is our sex actually determined. After conception,
The debate over Title IX is a complex one, with many sides relentlessly attacking each other’s approaches regarding the law. The Title IX advocates, largely comprised of women’s organizations such as the National Women’s Law Center (NWLC), take the approach that the law is the major reason women have achieved somewhat equal opportunities in athletics. The NWLC contends that abolishing Title IX would undo years of progress so far achieved. In sharp contrast with the Title IX advocates are the Title IX opponents, who are largely comprised of the National Wrestling Coaches Association (...
Frankl, Daniel. "Gender Bias in Sports: Separate and Not Equal"" Sports Media's Digest, Jan. 2005..
... athletes feel more secure than their female counterparts. Lopiano and Sommers create realistic, reliable and clear material that uncovers how female athletes struggle to gain media coverage. The article by Lopiano (2008) is broad and simple, while the article by Sommers (2010) is specific and precise. Overall, Lopiano and Sommers prove to be effective, straightforward, and unique sources that challenge the inconsistency of media coverage between female athletes and male athletes.
In Women’s Brains, Gould argues that the data used by scientist Paul Broca was misused only in order to confirm the inferiority of women and other discriminated groups. Through anthropometrics, the scientific study of the measurements and proportions of the human body, Broca and his colleagues “proved” that women were intellectually inferior, because on average the size of their brains were smaller than men’s. Even though Broca’s numbers were sound and accurate, Gould states, “. . .science is is an inferential exercise, not a catalog of facts. Numbers, by themselves, specify nothing” (Gould 1). This means that even though the data proves that women’s brains are smaller than men’s it did not take into account body stature, height, weight, etc., which all contribute to the size of the brain in a human body. As Gould describes, “. . .the true figure [of the difference of brain
I will conclude this paper by discussing some of the behavioral traits that have been thought to correlate with differing degrees of sexual dimorphism and their plausibility. Anatomical Structures Used to Study Human Sexual Dimorphism To discuss sexual dimorphism, one must first define the term. Webster’s Dictionary defines sexual dimorphism as “the condition in which differences i... ... middle of paper ... ...
Swaab, Df. "Sexual Differentiation Of The Human Brain: Relevance For Gender Identity, Transsexualism And Sexual Orientation." Gynecological Endocrinology 19.6 (2004): 301-312. Informa Healthcare . Web. 7 Apr. 2014.
What controls a human's sexual orientation? The long-standing debate of nature versus nurture can be extended to explaining human sexual orientation. Is it biological or environmental? The biological explanation has been gaining popularity amongst the scientific community although it is only based on speculations. It is argued that sexual orientation is linked to factors that occur during sexual differentiation. The prenatal exposure to androgens and their affect on the development of the human brain play a pivotal role in sexual orientation (2). Heredity is also part of the debate. Does biology merely provide the slate of neural circuitry upon which sexual orientation is inscribed? Do biological factors directly wire the brain so that it will support a particular orientation? Or do biological factors influence sexual orientation only indirectly?
Claussen, Cathryn L. "Female sport participation in America: the effectiveness of Title IX after 35 years." The International Sports Law Journal 3-4 (July-Oct 2007)
"Scans See 'Gay Brain Differences'" BBC News. N.p., 16 June 2008. Web. 25 Feb. 2014. .
Some studies suggest that a potential origin is the primary female sex hormone, estrogen. It has neuro-protective and inflammatory-modulating effects on the brain. In ischemic brain injuries, gender related variances have been linked to this protective influence of estrogen; it was shown to improve post ischemic cerebral reperfusion and prevent dysfunction of the vascular endothelium.2, 6 However, gender differences in brain injury are exhibited even with a decline of the female sex steroid at menopause. Depending on the chromosomal content (XX or XY), there is nonconformity in some molecular mechanisms of cell survival and death. This suggests that there are hormone-independent pathways underlying the sexual dimorphism.
In order to grasp the concept of social construction of gender, it is essential to understand the difference between sex and gender. Biologically, there are only two reproductive genital organs that are determinants of sex: the vagina and the penis. Sex is established solely through biological structures; in other words, genitalia are the basis of sex. Once a sex category is determined, gender, a human categorization socially attached to sex, is assigned based on anatomy. Gender typically references social or cultural differen...
In order to discuss the biology of gender identity and sexual orientation, it is necessary to first examine the differences between multiple definitions that are often mistakenly interchanged: sex, gender, sexual orientation, and gender identity. Sexual orientation is defined by LeVay (2011) as “the trait that predisposes us to experience sexual attraction to people of the same sex as ourselves, to persons of the other sex, or to both sexes” (p. 1). The typical categories of sexual orientation are homosexual, heterosexual and bisexual. Vrangalova and Savin-Williams (2012) found that most people identify as heterosexual, but there are also groups of people that identify as mostly heterosexual and mostly gay within the three traditional categories (p. 89). This is to say that there are not three concrete groups, but sexual orientation is a continuum and one can even fluctuate on it over time. LeVay (2011) also defines gender as “the ...
Sex and gender are terms that are mixed up from day to day and seen as similarities rather than differences. Sex is what distinguishes people from being either male or female. It is the natural or biological variations between males and females (Browne, 1998). Some of these variations are genitals, body hair and internal and external organs. It is the make-up of chromosomes, men have one X and one Y chromosome and women have two X chromosomes, these are responsible for primary characteristics (Fulcher and Scott, 2003). Gender on the other hand refers to the sociological differences between male and female. This is teaching males and females to behave in various ways due to socialisation (Browne, 1998). Example: masculinity and femininity. Girls are supposed to show their femininity by being non-competitive, sensitive, dependent, attractive and placid. If and when some girls don’t succeed in keeping this image they will be referred to as a tomboy. On the other hand, boys show their masculinity through aggression, physical strength...