The Biological explanation of gender

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The Biological explanation of gender
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Lesson Objectives

• By the end of this lesson you will
• understand
• Typical sex chromosome patterns
• Atypical sex chromosome patterns
• Dabbs et al (1995)

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Biological explanations

• Biopsychologists assume that all gender
  differences are totally attributed to chromosomal
  differences, differences in brain structure
  function and differences in hormonal activity.

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Biological explanations

• The normal human
• body contains 23 pairs
• of chromosomes.
• Each pair of
• chromosomes
• carries genes that
• control different
• characteristics.
• Biological sex is
• determined by the
• 23rd pair. So females
• have the genotype XX
• and males the
• genotype XY.

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Atypical sex-chromosomes

• Any combination of sex chromosomes other than XX
  or XY is seen as atypical.
• Klinefelters and Turners syndrome are examples
  of conditions which result from atypical sex
  chromosome conditions.

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Klinefelter Syndrome
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Turner syndrome
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Atypcial Chromosomes
Klinefelter Syndrome (XXY) Caused by the presence of an extra X chromosome Biological male with a physical appearance of male Affects between 1 in 500 and 1 in 1000 males Psychological effects poor language skills which affects reading ability, passive temperament Physical effects less body hair than normal male, underdeveloped genitals, long legs in relation to torso, infertile Turner Syndrome (XO) Caused by the absence of an X chromosome Biological female with the female external appearance Affects 1 in 2500 Psychological effects higher than average reading ability lower than average spatial ability, visual memory and mathematical skills difficulty is social adjustment Physical effects ovaries fail to develop, short squat body with webbed neck
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Atypical Chromosomes

• What does studying people with atypical sex
  chromosome patterns allow us to conclude what
  about gender?

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Atypical Chromosomes

• It provides evidence that our biological makeup
  is responsible for gender-related behaviour.
• For example, by comparing someone with typical
  chromosomes to someone with atypical chromosomes
  you can make clear comparisons what aspects of
  their behaviour have a genetic cause.
• Studies to support
• Imperato mc Ginley et al (1979)
• Money and Erhardt (1972)

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Chromosomes

• Give the typical sex chromosome pattern for the
  following
• a male
• a female
• (2 marks)

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Exam questions

• Q. Identify one atypical sex chromosome pattern
  and outline how it might affect an individual.
• (3 marks)

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Past papers

• Victoria is five years old and she is different
  from other girls of her age.
• She is smaller in height and has a webbed neck.
  At school, her
• teachers have commented that she has good verbal
  skills but her
• mathematical skills are poor. Medical tests have
  revealed that Victoria
• has a sex chromosome pattern XO.
• Name the atypical sex chromosome syndrome
  described above.
• (1 mark)
• Q. Identify how Victorias sex chromosome pattern
  differs from that of most girls. (1 mark)
• Explain how studying people like Victoria can
  contribute to our understanding Of gender.
• (2 marks)

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Summary

• What three things have you learned today.
• Q Name one sex hormone and give an example of how
  this hormone might affect a persons behaviour.
  (2 marks)
• Discuss biological explanations of gender
  development. Refer to at least one study in your
  answer. (10 marks)