Psychology
The Role of Chromosomes And Hormones In Gender
Chromosomes play a fundamental role in determining an individual's biological sex, with females typically having two X chromosomes and males having one X and one Y chromosome. Hormones, such as testosterone and estrogen, further influence the development of gender-specific traits and behaviors. While chromosomes provide the initial blueprint for sex differentiation, hormones contribute to the physical and behavioral characteristics associated with gender.
Written by Perlego with AI-assistance
Related key terms
1 of 5
12 Key excerpts on "The Role of Chromosomes And Hormones In Gender"
eBook - PDFChild Psychology
Development in a Changing Society
- Robin Harwood, Scott A. Miller, Ross Vasta(Authors)
- 2012(Publication Date)
- Wiley(Publisher)
Genes and Hormones As you read in Chapter 3, the sex chromosomes—the X and the Y chromosomes—determine whether individuals develop as boys or girls. The X chromo- some is similar in size to the autosomes and carries a good deal of genetic material, whereas the Y chromosome is much smaller and has many fewer genes. When the pair of sex chro- mosomes inherited from the parents consists of two X chromosomes (XX), the person is female; when it is made up of one of each type (XY ), the person is male. The sex chromosomes have no influence at all on the fertilized zygote for about 6 weeks. At that time, if the embryo is genetically male (XY ), the Y chromosome causes a portion of the embryo to become the male gonadal structure—the testes. Once this is accomplished, the Y chromosome does not appear to play any further role in the process of sex differentiation. If the embryo is genetically female (XX), the sex chromosomes pro- duce no change at 6 weeks. At 10 to 12 weeks, however, one X chromosome causes a por- tion of the embryo to become female gonads—the ovaries. From this point on, sex differentiation is guided primarily by the hormones produced by the testes and the ovaries. In addition to genes on the sex chromosomes, other genes can affect males and females differently. Usually, this occurs when the expression of a trait requires the presence of cer- tain levels of sex hormones. Such traits are called sex-limited traits. The gene for bald- ness, for example, may be carried by either men or women, but the characteristic appears primarily in men because high levels of male hormones are needed for it to be expressed. Sex differentiation The biological process through which physical differences between sexes emerge. Sex-limited traits Genes that affect males and females differently but that are not carried on the sex chromosomes.
eBook - PDFChild Psychology
A Canadian Perspective
- Alastair Younger, Scott A. Adler, Ross Vasta(Authors)
- 2014(Publication Date)
- Wiley(Publisher)
Understanding the origins of those differences has proven to be a greater challenge. In the following sections, we discuss how biological factors and socialization contribute to the development of these differences. We turn first to biological factors. These include the genetic, structural, and physiological processes that distin- guish males and females. Like most other species, humans exhibit sexual dimorphism; that is, the Learning Objective 16.3 Understand the role of biological influences in the development of sex differences. 633 Biological Influences on Gender-Role Development male and female are biologically different for the purpose of reproduction (Rhen & Crews, 2008). As noted earlier, the process through which these biological differences emerge is called sexual dif- ferentiation. Many of the biological influences on gender-role development appear to result from nature’s preparing the individual in this way to participate in the reproduction process. GENETIC INFLUENCES As we explained in Chapter 3, the sex chromosomes—referred to as the X and the Y chromo- somes—determine whether we develop as males or females. The X chromosome is of about average size as chromosomes go, and carries a good deal of genetic material; the Y chromosome is much smaller and has fewer genes. When the pair of sex chromosomes inherited from the parents consists of two X chromosomes (XX), the individual is female; when it is made up of one of each type (XY), the individual is male. The sex chromosomes have no influence on the fertilized zygote for about six weeks. At that point, if the embryo is genetically male (XY), the Y chromosome causes a portion of the embryo to become the male gonadal structure—the testes. Once this is accomplished, the Y chromosome does not appear to play any further role in the process of sexual differentiation. If the embryo is genetically female (XX), the sex chromosomes produce no change at 6 weeks.
eBook - PDF- Peggy T. Cohen-Kettenis, Friedemann Pfäfflin(Authors)
- 2003(Publication Date)
- SAGE Publications, Inc(Publisher)
(Loehlin & Martin, 2000), and held more masculine attitudes than females with a female twin (Miller & Martin, 1995). The data coming from both clinical and nonclinical groups are thus sug-gestive of a hormonal influence on a limited number of gender role behav-iors. Whether prenatal hormones directly influence gender identity is less clear. This does not mean that gender role behaviors, even those that are most likely influenced by hormones, are entirely determined by biological forces. Environmental forces exert their influence, despite the fact that for some behaviors limits are set. SUMMARY Sex, gender identity, and gender role usually develop in accordance with each other. The cornerstone of this development is the sex-dimorphic con-stitution established at the very beginning of human life when egg and sperm fuse. In addition to the 46 chromosomes, which are not sex-dimor-phic, an individual will have either two X chromosomes and thus be female or one X and one Y chromosome each and thus be male. In the first weeks after conception, the internal and external genitals are still undifferentiated and identical in female and male embryos. Under the influence of a gene located on the Y chromosome internal and external genitals transform into male structures or, when this gene is absent, follow the route to female structures. Gonadal hormones influence the development and programming of the central nervous system. The newborn does not yet have self-awareness of his or her sex and gen-der. Such self-awareness evolves gradually during infant life. A number of different theories have tried to explain this evolution, emphasizing the influ-ences of cognitive and affective learning in the interaction with parents, peers, and environment. Gender labeling, gender stability, and gender consistency develop gradually.
eBook - PDFPsychology
Modules for Active Learning
- Dennis Coon, John Mitterer, Tanya Martini, , Dennis Coon, John Mitterer, Tanya Martini, (Authors)
- 2021(Publication Date)
- Cengage Learning EMEA(Publisher)
Genetic Sex Becoming male or female may seem simple enough. Genetic sex is determined at the instant of conception: Two X chromosomes initiate female development; an X chro-mosome plus a Y chromosome produces a male. A woman’s ovum always provides an X chromosome because she has two X s in her own genetic makeup. In contrast, one-half of the male’s sperm carry X chromosomes and the other half carry Y s. Even at conception, however, variations may occur because some individuals begin life with too many or too few sex chromosomes (Crooks & Baur, 2017). For example, in Klinefelter’s syndrome , a boy is born XXY , with an extra X chromosome. As a result, when he matures, he may appear feminine, have undersized sexual organs, and be infertile. In Turner’s syndrome, a girl is born with only one X chromosome and no Y chromosome. As an adolescent, she may appear boyish and she also will be infertile. Hormonal and Gonadal Sex While genetic sex stays the same throughout life, it alone does not determine biological sex. In general, sexual characteristics are also related to the effects of sex hormones before birth. (Hormones are chemi-cal substances secreted by endocrine glands.) The gonads (or sex glands) affect sexual development and behavior by secreting estrogens (female hormones) and androgens (male hormones). The gonads in the male are the testes; female gonads are the ovaries. The adrenal glands (located above the kidneys) also supply sex hormones. Everyone usually produces estrogens and androgens. Sex differences are related to the proportion of these hor-mones found in the body. In fact, prenatal development of male or female anatomy is largely due to the presence or ab-sence of testosterone (tes-TOSS-teh-rone), one of the an-drogens, secreted mainly by the testes (LeVay & Baldwin, 2015). For the first six weeks of prenatal growth, geneti-cally female and male embryos look identical.
No longer available |Learn more- Philip Banyard, Christine Norman, Gayle Dillon, Belinda Winder, Philip Banyard, Christine Norman, Gayle Dillon, Belinda Winder(Authors)
- 2019(Publication Date)
- SAGE Publications Ltd(Publisher)
BRAIN AND BEHAVIOUR: SEX DIFFERENCES 285 of gender identity is incompatible with their biological sex. Gender role refers to the behaviours that society deems are appropriate or acceptable to be expressed by a particular sex, for example, mowing the lawn versus changing nappies (no prizes for guessing which role is attached to which gender). Some individuals, however, may challenge traditional conceptions of sex and gender as they identify as ‘non-binary’, also called ‘genderqueer’. This umbrella term relates to individuals who may identify different genders at different times, both gen- ders at the same time or no gender at all. In many political, legal, medical and occu- pational settings there is an inherent assumption that individuals fall into two discrete categories. If you were able to influence public policy, how might you suggest helping and supporting individuals who identify as non-binary? 12.2 THE PROCESS OF SEXUAL DIFFERENTIATION 12.2.1 Genetic sexual differentiation Human cells contain 46 chromosomes arranged into 23 pairs. Twenty-two of these pairs of chromosomes are autosomes (non-sex chromosomes), and do not differ between males and females. They are not significantly involved in the process of sexual differentiation, which is the process by which an individual begins to develop into either a male or a female. The final pair of chromosomes, known as sex chromosomes, differs between males and females. The sperm (male reproductive cell) and the egg (female reproductive cell) both only contain one copy of the 23 chromosome pairs common to humans. Once the sperm reaches the nucleus of the egg, they fuse together to form a complete set of 23 chro- mosomal pairs (fertilisation). In humans, eggs always contain an X sex chromosome while sperm can potentially carry either an X or a Y sex chromosome. If the sperm contains an X sex chromosome, the embryo will eventually develop into a female, as two X chromosomes (XX) are present.
eBook - PDF- Michele A. Paludi(Author)
- 2004(Publication Date)
- Praeger(Publisher)
The physiological level involves the systems of cells, tissues, and organs that develop in the individual (e.g., hormonal and neural) and how they function in reproduction. Reproduction is a physiological process. Indi- viduals carrying two Xs are labeled women ("females" in medical practice); those carrying an X and a Y chromosome are labeled men ("males" in med- ical practice). Mammals can reproduce by cloning offspring, a process in which intro- ducing appropriate cells from one organism into the nucleus of an appropri- ate cell in another organism leads to the formation of an embryo. However, this embryo must be incubated in an organism with XX chromosomes, whose hormonal functions will make development, growth, and birth possible. To 246 Praeger Guide to the Psychology of Gender date, it is not known that humans can be cloned in this fashion. The psy- chosocial/societal processes whereby this type of reproduction will take place are unknown. The process whereby the two gametes are usually mixed in humans is com- plicated and offers many opportunities for unusual combinations of gametes to occur. The psychosocial/societal gender development of individuals car- rying such unusual combinations is insufficiently studied and understood. How Gender Gets Defined Gender is the psychosocial/societal integration of the codes of activity, dress, social relations, and societal status prescribed for individuals on the basis of their presumed sex. How Many Sexes? How Many Genders? The suggestion that there may be more than two sexes (XX and XY) is based on the fact that individuals usually considered women or men as to their gender may have different combinations of X and Y chromosomes. Based on the chromosomes carried, individuals may be categorized variously as intersexes, or as demonstrating syndromes such as Turner's, Klinefelter's, and so on.
eBook - ePub- Judith E. Owen Blakemore, Sheri A. Berenbaum, Lynn S. Liben(Authors)
- 2013(Publication Date)
- Psychology Press(Publisher)
This process of genetic regulation (also called differential gene expression) is also responsible for sex differences in some traits. Many of the genes for baldness are on the autosomes, but they are expressed primarily in the presence of high levels of testosterone, so men are much more likely than women to become bald. It is also possible that some behavioral sex differences are influenced by autosomal genes that are differentially expressed in males and females because of other factors that differ between them. An obvious factor is hormones, but there are other genetic and environmental differences between males and females that might affect gene expression, such as diet and sun exposure. It is thus reasonable to hypothesize that sex differences in gene expression lead to behavioral sex differences, but we currently have no data that provide a good test of the hypothesis.Summary: Genetic Effects On Gender Development
Although there is good reason to think that genes on the sex chromosomes affect gender development, the issue is not easy to study because there are very few conditions in which effects of those genes can be studied in isolation. There is intriguing evidence from people with TS that the X chromosome plays a role in spatial ability and social skills. There is currently no evidence for human behavioral effects of genes on the Y chromosome, but studies in rodents suggest that such evidence may eventually be found. Genes on the autosomes might also influence behavior differently in males and females, through regulation by hormones or social experiences, but there is little direct evidence on this issue.Hormonal Perspectives On Gender Development: Sex Hormones Affect More Than the Genitalia
There is good reason to hypothesize that sex hormones play a role in gender development. Sex hormones are crucial for physical sexual differentiation, and one of the most important biological differences between the sexes is that high levels of androgens are primarily responsible for the establishment of the male physical phenotype. Given that the brain is a physical structure, it seems likely that the brain and the behavior it subserves are also affected by sex hormones. Studies in a variety of nonhuman species establish without question that this is true: sexual differentiation of brain structure and function (including behavior) is dependent on the presence or absence of sex hormones, especially androgen. Furthermore, studies in human beings increasingly show the importance of sex hormones for sexual differentiation of behavior. These studies generally test what are called hormonal theories of (or hormonal perspectives
eBook - PDF- Jon C. Horvitz, Barry L. Jacobs(Authors)
- 2022(Publication Date)
- Cambridge University Press(Publisher)
Sex hormones, particularly testosterone and other androgens, play first organizing and later activating roles in sexual behavior. These roles are analogous to the relation between constructing a musical instrument and later playing it. The way that an instrument is constructed limits or constrains the sounds that it can produce when played in the future. Similarly, the organizing effects of hormones on the early development of sexual anatomy and brain circuits can influence the sexual feelings and behaviors that are activated when sex hormones are released in later years. Figure 7.2 Testosterone and estradiol are closely related molecules. In the ovaries, cholesterol is converted to testosterone. Just a single enzyme, aromatase, is needed to convert testosterone to estradiol (top). Deficiencies in aromatase cause an abnormal build-up of testosterone and low levels of estradiol (bottom). Ovary (Several steps) Cholesterol Aromatase Testosterone CH 3 O CH 3 OH Estradiol HO CH 3 OH (Several steps) Cholesterol Aromatase Testosterone CH 3 O CH 3 OH Estradiol HO CH 3 OH 278 SEX Membrane Cytoplasm mRNA Protein mRNA DNA Nucleus Steroid hormone 1 2 3 4 1 The steroid hormone binds to a receptor inside the cell 2 The steroid-receptor complex moves to the nucleus of the cell 3 The steroid-receptor complex binds to DNA 4 Genes are expressed and new proteins are generated Figure 7.3 Steroid hormones. Steroid hormones are capable of binding to receptors within the cell cytoplasm, producing long-lasting effects on the cell. KEY CONCEPTS • The testes and ovaries are endocrine glands that release high levels of testosterone and estradiol, respectively. • Like all steroid hormones, testosterone and estradiol are small, fat- soluble molecules capable of crossing cell membranes and binding to receptors located within the cytoplasm of the receiving cell. • Steroid hormones can bind to DNA in the cell’s nucleus and alter gene expression, producing lasting changes in the cell’s functioning.
eBook - PDF- Colin Hamilton(Author)
- 2008(Publication Date)
- Bloomsbury Academic(Publisher)
I n d i v i d u a l D i f f e r e n c e s a n d G e n d e r 131 132 Aim and Overview The previous chapter concluded with a brief section on identifying within-sex variability associated with hormonal influences on the possession of gender-stereotype characteristics. This chapter will consider in more detail the nature of hormonal influences upon human behaviour and in particular upon human cognition. While the emphasis in this chapter will be upon within-sex variability associated with hormones, between-sex comparison will be noted where appropriate, as it was in the previous chapter. The chapter will begin with a discussion of the theoretical frameworks associated with hormones and cognition, the theoretical model or hypoth-eses of Geschwind and Galaburda (1985a, 1985b, 1987) and the principles of organizational and activational aspects of hormonal actions. Geschwind’s suggestions relate to the influence of prenatal hormonal influences and therefore would be regarded, in the main, as organizational influences upon the CNS, hormonal influences upon the early construction and organization of the CNS which tend to be long-lasting. However, hormonal influences in humans are also subject to daily, lunar and annual fluctuations and these temporary influences in adults form the basis of the activational influences upon the CNS. The first element of this section will consider the methodological tools employed by psychologists which have aimed to identify behavioural mark-ers of early organizational hormonal influences: the use of handedness, foot-edness and more recently finger characteristics, for example digit ratios (Manning and Taylor 2001; Manning et al. 1998, 2001). In addition the dis-cussion will consider clinical groups where early prenatal hormonal disrup-tion has occurred. The empirical research component of the chapter will consider initially the studies which have looked at proposed prenatal influences employing the behavioural markers identified above.
eBook - PDFDNA
Promise and Peril
- Linda L. McCabe, Edward R.B. McCabe(Authors)
- 2008(Publication Date)
- University of California Press(Publisher)
Gender reversal was com-pletely acceptable within the culture of this community. The authors con-cluded that the normal exposure of the central nervous system to testos-terone during development would appear to make a substantial contribution to male gender identity. The experiences of these individu-als demonstrated that the in X uence of testosterone could override the in X uence of the individuals’ sex of rearing as girls. The absence of socio-GENDER AS A SPECTRUM, NOT A DICHOTOMY 97 cultural barriers to gender identity change in this community clearly facil-itated the shift in gender identity and role. . . . Genotype is an individual’s genetic constitution. The genotypic sex is the entire genetic makeup of that individual as it in X uences sex determination and sexual differentiation. Sex determination is the biological decision-making process that takes the bipotential or multipotential early embryo capable of forming male or female gonads or genitalia and commits it toward a male or female phenotype. Genotypic sex can be subdivided into chromosomal sex and genetic sex. For most individuals, the chromosomal sex will re X ect the genotypic sex. The normal chromosomal complement, known as the karyotype, usually is 46,XX for a female and 46,XY for a male. The karyotype may be abnormal, such as: 45,X; 47,XXX; 47,XXY; or 47,XYY. A general but not inviolate rule is that the gonadal phenotype will be female in the absence of a Y chromosome and male if one or more Y chromosomes are present. This observation led physicians and investigators to speculate that a gene termed the testis-determining factor (TDF) resided on the Y chromosome. This proposal argued that the testis and maleness were con-ferred by the presence of this Y chromosomal gene. The ovary and femaleness were described as the “default” condition that would occur in the absence of TDF. Individuals with a 45,X karyotype have a collection of W ndings called Turner syndrome.
eBook - ePubGonadal Hormones and Sex Differences in Behavior
A Special Issue of developmental Neuropsychology
- Sheri A. Berenbaum(Author)
- 2014(Publication Date)
- Psychology Press(Publisher)
Consistency of findings across methods and species continues to provide support for two fundamental principles in psychoneuroendocrinology. First, sexual differentiation of the mammalian brain and behavior parallel sexual differentiation of the body: High levels of androgens (and metabolites) present during critical periods cause development to proceed in a masculine direction, whereas low levels produce feminine development. Second, hormones exert behavioral effects at various times in development through permanent changes in the wiring and sensitivity of the brain (organizational effects) and through ongoing changes to neural circuitry (activational effects). Although these two principles remain correct in broad form, recent work in both human and nonhuman species—much of it presented in articles in this special issue—reveals complexities and provides questions and answers about the ways in which hormones affect behavior.Several articles in this special issue expand our knowledge about the effects of early (organizational) hormones on a variety of behaviors and aspects of brain structure and function in a variety of species. These studies reflect the range of methodology available to study the behavioral effects of early hormones. Clark and Galef (this issue) show that, in rodents, a variety of behavioral, morphological, and reproductive characteristics are affected by intrauterine position, which reflects exposure to variable levels of testosterone. Their results encourage studies of human opposite-sex twins (as illustrated in the work of McFadden, this issue), and remind us of the value of examining both physical and behavioral traits, and the complexity of hormonal effects on behavior, including the importance of hormone sensitivity and environmental responses to the organism. Fitch, Cowell, and Denenberg (this issue) clearly demonstrate that sexual differentiation is not determined simply by the amount of androgens present in early development, but depends on an active feminizing process induced by ovarian hormones. Michael and Zumpe (this issue) describe how steroid hormones are taken up in the primate brain, and suggest that masculinization occurs at least in part through the conversion of testosterone to estradiol. McFadden (this issue) provides a comprehensive review of sex differences in the human auditory system and indicates how hormones present at several times in development are likely to be responsible for these sex differences. He also demonstrates the value of examining hormonal influences on basic sensory and perceptual processes.
eBook - PDF- Howard Moltz(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
Such a conclusion is not unreason-able in view of the well-known sex differences in chromosome char-acteristics. A somewhat more sophisticated hypothesis, however, might suggest that these sex-chromosome differences lead to the development of a testis in the male and an ovary in the female and that their respective hormonal secretions then underlie the behav-ioral differences observed. Current evidence indicates that neither of these hypotheses provides an adequate model for understanding the development of sex-typical mating behaviors. For example, in the rat administration of the ovarian hormones, estrogen and progesterone, to the male does not mimic the effects of administering these same hormones to the female. Similarly, injection of testosterone in the female does not mimic the effects of testosterone injection in the male, indicating that adult male and female rats possess different potentials for responding to testicular and ovarian hormones, respec-tively. 234 RICHARD E. WHALEN The modern study of the development of sex differences in hor-monal reactivity has had a profound impact upon our current ideas of the ontogeny of sexuality. The germinal study in the area was pub-lished in 1959 by Phoenix, Goy, Gerall, and Young. These workers treated pregnant guinea pigs with the androgen, testosterone propio-nate (TP). The female offspring of mothers treated with a low dose of TP during pregnancy were genitally unmodified at birth, while those females whose mothers had received a high TP dose were pseudohermaphroditic at birth, possessing external genitals indistin-guishable from those of normal males. When these androgenized animals matured, they were treated with estrogen and progesterone at dosage levels known to induce sexual receptivity in normal fe-males. They were found to be significantly less responsive to gon-adal hormones than control females.
Index pages curate the most relevant extracts from our library of academic textbooks. They’ve been created using an in-house natural language model (NLM), each adding context and meaning to key research topics.
