Difficulty: Introductory | Prerequisites: Chapters 1–2
This chapter explores how biology, culture, and gender interact to shape behaviour. It covers natural selection, evolutionary psychology, sex vs. gender, gender roles, cultural norms, and the nature-nurture interplay. The material is shorter than earlier chapters but conceptually important for understanding group differences.
Biology and culture are not opposing forces; they interact. Universal behaviours arise from shared biology, but cultural norms, gender roles, and peer influence shape how those behaviours are expressed. The sex/gender distinction matters: sex refers to reproductive categories, gender to the social meanings societies attach to them. Gender roles are not fixed by evolution; they vary across time and culture.
Natural selection
The evolutionary process by which heritable traits that best enable organisms to survive and reproduce in particular environments are passed to subsequent generations.
Evolutionary psychology
The study of the evolution of cognition and behaviour using principles of natural selection.
Sex
Categories into which humans are divided on the basis of reproductive functions. Sex differences refer to biological differences between females and males in the reproductive sense.
Gender
Meanings that individuals and societies ascribe to males, females, and non-binary categories. Gender differences refer to differences between women and men in the social sense.
Gender role
A set of behavioural expectations (norms) for males and females. Gender roles vary across time and culture.
Culture
The enduring behaviours, ideas, attitudes, and traditions shared by a large group of people and transmitted from one generation to the next.
Norms
Standards for accepted and expected behaviour. Prescribe "proper" behaviour and proscribe "improper" behaviour.
Epigenetics
The study of environmental influences on gene expression that occur without changes to the DNA sequence itself.
In simple terms, your environment can switch genes on or off without altering the underlying code.
Universal behaviours arise from our shared biological similarities.
Natural selection and evolutionary psychology provide frameworks for understanding why certain behaviours are widespread.
Biology and culture interact; they are not independent forces. Epigenetics illustrates this interaction: environmental factors can alter gene expression without changing DNA.
Sex is a biological category (reproductive function). Gender is a social category (meanings attached to being male, female, or non-binary).
The original sex/gender separation reflects a nature/nurture conceptual framework.
Gender roles are sets of behavioural norms for males and females.
They have changed dramatically over the past half century.
Behavioural changes have accompanied attitude changes.
Role models may be a crucial catalyst for shifts in gender roles.
Gender roles differ across cultures, but trends toward greater gender equality appear across many cultures.
These changes signal that evolution and biology do not render gender roles unchangeable.
Culture enables a high degree of behavioural diversity thanks to our highly adaptive brain.
All cultures have norms: standards for accepted and expected behaviour.
Norms can seem arbitrary and confining to those who do not accept them.
Peer-transmitted culture may matter more than parental nurture for personality development.
Genetic influences explain roughly 40% of individual variation in personality traits.
Shared environmental influences (home, parenting) account for only 0 to 1%.
Cultural norms powerfully affect attitudes and behaviour, but they do not operate independently of biology.
Students sometimes treat biology and culture as an either/or. The course emphasises that they interact. Behaviour is almost always a product of both.
Students may assume gender roles are biologically fixed. The evidence that gender roles have changed substantially over time and vary across cultures counters this.
The small contribution of shared family environment (0 to 1%) surprises many students. This does not mean parents do not matter at all; it means that the home environment shared by siblings explains very little of the variance in personality traits, compared with genetics and non-shared environment (including peers).
⚠️ Know the distinction between sex (biological) and gender (social). Expect a definition question.
⚠️ Be able to explain how biology and culture interact, using epigenetics as an example.
⚠️ Understand that gender roles vary over time and across cultures, and what this implies about biological determinism.
⚠️ The peer-transmitted culture finding (genetic influences ~40%, shared home environment ~0 to 1%) is a common exam point.
Fill in the blank: ______ refers to reproductive categories; ______ refers to social meanings attached to those categories. (Sex; gender)
True or False: Gender roles are entirely determined by biology and cannot change. (False.)
Fill in the blank: The study of how environmental factors influence gene expression without altering DNA is called ______. (Epigenetics)
True or False: Shared family environment explains most of the variance in personality traits. (False. It accounts for roughly 0 to 1%.)
Q: What is the difference between sex differences and gender differences?
A: Sex differences are biological differences between males and females in the reproductive sense. Gender differences are differences between women and men in the social sense, shaped by cultural norms and expectations.
Q: Give an example of how biology and culture interact to produce behaviour.
A: Epigenetics shows that environmental factors (stress, diet, social experience) can switch genes on or off without changing the DNA sequence. A person's genetic predisposition toward anxiety, for example, may be amplified or dampened by the cultural and social environment they grow up in.
Q: Why does the evidence that gender roles have changed over time matter for the nature-nurture debate?
A: If gender roles were entirely determined by biology and evolution, they would be stable across time and cultures. The fact that they have shifted substantially (more women in the workforce, changing attitudes toward gender equality across many cultures) demonstrates that social and cultural forces play a significant role and that biology does not make gender roles unchangeable.
The individualism/collectivism distinction introduced in Chapter 2 returns here in the context of how culture shapes norms and gender roles. The concept of norms connects directly to Chapter 6 (Conformity and Obedience), where social norms drive conformity. Evolutionary psychology provides a framework that recurs throughout the course when discussing attraction, aggression, and prosocial behaviour.
Natural selection, evolutionary psychology, sex, gender, sex differences, gender differences, gender role, culture, norms, prescriptive norms, epigenetics, peer-transmitted culture, individualism, collectivism, nature-nurture, biology and culture, gender equality, NYU social psychology, Chapter 5