Gender Issues In Psychology (PSY - 512)
BIOLOGICAL DIFFERENCES BETWEEN GENDERS:
Biological differences between males and females are found in three ways:
· In chromosomes
· In hormones
· In structure of the nervous system
Hormones and chromosomes are the:
· Bases of masculinity and femininity
· Structural units and carriers of heredity
· Play important role in various human behaviors
Endocrine system is a network of glands that produce and secrete chemical messengers (hormones), directly
into the blood stream. This activity is controlled by hypothalamus: the important relay station and significant
Hormones and Chromosomes:
Hormones and chromosomes are not only bases of masculinity and femininity and structural units of heredity,
they play important role in various human behaviors. Endocrine System is a network of glands that produce
and secrete chemical messengers that are called hormones, directly into the blood stream. Theses glands are
controlled by hypothalamus that is important relay station and significant brain structure. Pituitary glands
(also called master glands) stimulate or inhibit secretion of hormones from other glands. Sex and reproduction
hormones are called, Steroid hormones. Reproductive organs ovaries (in females) and testes (in males) are
Sexual Differentiation and role of Chromosomes:
Sexual dimorphism is existence of two sexes (male & female) in a species, including differences in genetics,
gonads, hormones, internal genitalia and external genitalia. The process of sexual differentiation starts when
conception takes place. Chromosomes are threadlike structures that are structural carriers of heredity, play very
important role in sex differentiation. In human beings there are 23 pairs of chromosomes. At the time of
conception half amount of chromosomes is received from mother side and half from father side. 23rd pair of
chromosome is called sex chromosome in females it is XX and in males it is XY. Genes contain genetic
information carried on chromosomes. Researchers claim that XY chromosomal makeup may not be as stable
as XX and therefore play a role in higher mortality rates for men. XX chromosomal makeup and the hormone
estrogen seem to make women less vulnerable to physical problems so women live longer lives.
Sex Chromosomal Abnormalities:
Sudden structural changes in the genes are called mutations. These mutations lead to negative consequences in
individual's development. Some times deleted or duplicated number of chromosomes also causes abnormalities
in an individual. Researches have found that disorders in sex chromosomes lead to problems in gender role
development, intelligence, growth and hormone production.
Female Sex Chromosome Abnormalities:
This syndrome occurs when individual inherit only one X chromosome and their sex chromosomal structure is
Such cases are females in sex with abnormal growth patterns. They are short in stature, averaging 4 foot 7
inches as adults, and often have distinctive webbed necks (i.e., extra folds of skin), small jaws, and high arched
palates. They generally lack prominent female reproduction ability. They have exceptionally small, widely
spaced breasts, broad shield-shaped chests, and turned-out elbows. Their ovaries do not develop normally and
they do not ovulate.
Gender Issues In Psychology (PSY - 512)
They also have a higher than average incidence of thyroid disease. In some individuals, there is slight mental
retardation. Turner's syndrome is rare. Current estimates of its frequency range from 1 in 3,000 female infants
to 1 in 5,000.
If diagnosed in early childhood, regular injections of human growth hormones can increase their stature by a
few inches. Beginning around the normal age of puberty, estrogen replacement therapy can result in some
breast development and menstruation. These treatments allow Turner's syndrome women to appear relatively
Metafemales or triple-X females:
Such females inherit three X chromosomes. Their chromosomal structure is XXX. As adults, these "super-
females" are usually an inch or so taller than average with unusually long body structure. They have normal
development of sexual characteristics and are fertile. They may have slight learning difficulties and are usually
in the low range of normal intelligence. They tend to be emotionally immature for their size during childhood.
This type of chromosomal abnormality is less rare than Turner syndrome.
Male Sex Chromosome Abnormalities:
Individual with this syndrome inherit on extra X chromosome and their chromosomal structure is XXY. They
characteristically have relatively high-pitched voices, feminine body contours as well as breast enlargement, and
comparatively little facial and body hair.
They are sterile or nearly so, and their testes and prostate glands are small. As a result, they produce relatively
small amounts of testosterone The feminizing effects of this hormonal imbalance can be significantly
diminished if Klinefelter syndrome boys are regularly given testosterone from the age of puberty on.
Klinefelter syndrome men are an inch or so above average height. They also are likely to be overweight. They
usually have learning difficulties as children, especially with language and short-term memory.
If not given extra help in early childhood, this often leads to poor school grades and a subsequent low self
esteem. Klinefelter syndrome is not diagnosed until they are tested for infertility. Klinefelter syndrome males
with more than two X chromosomes usually have extreme symptoms and are often mentally retarded.
The individual with this abnormality receive extra Y chromosome and their chromosomal structure is XYY. As
adults, these "super-males" are usually tall (above 6 feet) and generally appear and act normal. However, they
produce high levels of testosterone. During adolescence, they often are slim, have severe facial acne, and are
poorly coordinated. They are usually fertile and lead ordinary lives as adults. Majority remain unaware that they
have a chromosomal abnormality.
Early studies of XYY syndrome done in European prisons initially led to the erroneous conclusion that these
men were genetically predisposed to antisocial, aggressive behavior, below average intelligence, and
homosexuality. Contributing to the early view that XYY syndrome men have serious personality disorders.
However, some researchers suggest that the high testosterone levels of XYY men can make them somewhat
more prone to violence and that this may cause higher rates of wife beating.
Sex Differentiation in Reproductive System
X and Y chromosomes determine the sex of child being male of female. Both sexes have two sex-related
Wolffian system: The system with a capacity to develop into the male internal reproductive system .
Mullerian system: The system with a capacity to develop into the female internal reproductive system.
Sex development is almost the same for both sexes during the first six weeks of prenatal development & both
systems exist in both sexes.
External sex organ development starts after sex weeks of conception. But these organs are not differentiated at
this stage and further external sex development depends upon the amount of androgen and estrogen
Gender Issues In Psychology (PSY - 512)
hormones. Androgen & estrogen hormones are gonadal hormones. Both sexes produce these two hormones.
But in males' androgens and in females estrogens are in greater proportions. Testosterone is androgen and
estradiol is common estrogen. Progesterone is another gonadal hormone that play important role in females
The production of androgen hormone is determined by Y chromosome in males that stimulates sexual
Production of Testosterone (androgen) stimulates Wolffian system and degenerates the Mullerian system
that results in development of internal reproductive organs.
In female fetus X chromosome stimulate estrogen hormone that further leads to Mullerian system
development and degeneration of Wolffian system, which results in the development of female internal
reproductive organs. During prenatal development androgen & estrogen are very important for the
development of sex characteristics in both sexes.
During infancy and childhood gonadal hormones are produce in low quantities but during puberty these
hormones secretions increased and develop sexual maturity. Growth hormones are released from Pituitary in
adolescence play important role in muscular and bones development. Pituitary glands also release follicle
stimulating hormone (FSH) and luteninizing hormone (LH) that is involve in production of androgen and
estrogen hormones. In males testosterone is released by testes that are endocrine glands. It stimulates the
maturation of sex organs, production of sperms and prepare for reproduction. In females estrogen hormones
play important role in menarche; beginning of menstruation and ovulation. Progesterone hormone secreted
in females; controls menstrual cycle and significant during pregnancy.
Hormonal influences in both sexes:
Endocrine glands are the vital glands that release chemical substances, called hormones, into the bloodstream.
Hormones thus circulate throughout the body. Different organs are sensitive to different hormones. The
impact of hormones produces different actions at different locations.
Hormones directly related to sex differences and reproduction, are known as steroid hormones.
Gonads: The reproductive organs, glands , testes in males and ovaries in females, related to the steroid
hormones. The hypothalamus and the pituitary gland are the main brain structures that regulate the production
of sex hormones.
Hypothalamus causes the production of Releasing hormones. Gonadotropin- releasing hormone is one of
Gonadotropin- releasing hormone has active influence on the pituitary; as a result of this action, the pituitary
releases a number of other hormone.
The release of Tropic hormones results from this action.
Gonadotropins are one of these. Circulating through the bloodstream these hormones impact the testes and
ovaries, which are subsequently stimulated to produce their respective hormones. In males' androgens, and in
females' estrogens, are in greater proportions.
Testosterone is an androgen and estradiol is a common estrogen.
Progesterone is another gonadal hormone that plays an important role in females during pregnancy
A number of hormones other than steroid hormones are also involved, directly or indirectly, in reproduction
and related processes. Smaller and larger quantities of hormones affect several behaviors. For example
testosterone levels can affect performance on some tests. Women with high levels of testosterone perform
better on spatial tasks than women with low levels do, but men with low levels outperform men with high
levels. Females exposed to more quantities of androgen are tending to have behavioral characteristic like
males. University of California at Los Angeles observed the play behavior of such females with other female
siblings. Given a choice of transportation and construction toys, dolls and kitchen supplies, or books and board
games, these females preferred the more typically masculine toys--for example, they played with cars for the
same amount of time that boys did.
Study (Dabbs, 2000) revealed that individuals with high testosterone levels are associated with lower status
professions as high testosterone levels are related to impulsiveness and antisocial behavior. Comparative study
of college students and young men delinquents revealed that they have higher levels of testosterone.
Gender Issues In Psychology (PSY - 512)
Another study of male prisoners also revealed that high testosterone levels are associated with deferent types of
violence including sex and rule violations. As female also produce testosterones so, various studies have
conducted to find out relationship between testosterone and female behaviors. Results support hypothesis that
high testosterone is related to aggressive behaviors.
The Hormonal Cycle
ovaries and testes
Incl. tropic hormones;
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