The Biological explanation of gender

Lesson Objectives By the end of this lesson you will understand: 1. Typical sex chromosome patterns 2. Atypical sex chromosome patterns 3. Dabbs et al (1995)

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

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

Atypical sex-chromosomes Any combination of sex chromosomes other than XX or XY is seen as atypical. Any combination of sex chromosomes other than XX or XY is seen as atypical. Klinefelter’s and Turner’s syndrome are examples of conditions which result from atypical sex chromosome conditions. Klinefelter’s and Turner’s syndrome are examples of conditions which result from atypical sex chromosome conditions.

Klinefelter Syndrome

Turner syndrome

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

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

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)

Chromosomes Q. Give the typical sex chromosome pattern for the following: a male a female (2 marks)

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

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. Q. Name the atypical sex chromosome syndrome described above. (1 mark) Q.Identify how Victoria’s sex chromosome pattern differs from that of most girls. (1 mark) Q. Explain how studying people like Victoria can contribute to our understanding Of gender. (2 marks)

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