nature & behavior

7/26/2019 Nature & Behavior

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The Nature and Nurture ofBehavior

Even monkeys fall out of trees.

Japanese Proverb

The curious paradox is that when I acceptmyself just as I am, then I can change.

Carl Rogers



Let’s start with genetics . . .

Gene

A stretch of DNA that produces a specific protein, which in

turn forms building blocks of our bodies or drives theprocesses that allow us to live

DNA (deoxyribonucleic acid): molecule that containsgenes

Human instruction manual: genes affect physical features,such as eye color and height, and behavior

Dogs are bred for genetic disposition/behavior

One gene in fruit flies can be altered to produce courtshipbehavior between two males



Darwin’s Natural Selection

Key is genetic fit with environment

Mutation Depending on environment, genetic makeup or

organisms evolves throughout generations ofoffspring, producing changes in the dominant

physical features and behavior of a group oforganisms



Evolutionary Psychology

Using principles of natural selection, focuseson the evolution of behavior and the mind

Mating behaviors

One of the most studied areas in evolutionarypsychology

Why do we find certain characteristics attractivein a potential mate?



Evolutionary Psychology –

Gender Differences in Attraction Women prefer economic resources & older partners

Men prefer physical attractiveness & younger

partners

These differences may arise from the different social

roles the genders have historically held or because ofevolutionary factors

These differences are more typically seen in cultures withgender inequalities



Criticisms of Evolutionary

Explanations Evolutionary theories are circular and

sometimes untestable

Alternate explanation

Overall, women have fewer resources(Ganestead, 1993)



Behavioral Genetics

How much of the differences among peopleare due to their genes and how much are dueto the environment?

Genes cannot be described in isolation: they canonly be characterized in relation to the

environments in which they operate



Twin studies

Identical twins Zygote splits (monozygotic)

Fraternal twins Two separate zygotes (dizygotic)

Adoption studies Compared adopted kids with biological and

adopted parents



Temperament Studies

Examining how emotionally excitable an infant is

‘Easy’ babies are cheerful, relaxed & predictable

‘Difficult’ babies are more irritable, intense &unpredictable

Temperament is mostly stable and mostly based onheredity

Earlier temperament predicts later temperament and behavior

Identical twins have more similar temperaments than fraternaltwins



Nature vs. nurture?

The environment has very little effect onpersonality development

But that doesn’t mean that your parents don’teffect you at all

Their influence can be seen in your attitudes, values,

manners, religion, and politics Most behaviors/traits are an interaction of

your genes and the environment



Environmental Influence

Should we really blame the parents?

NO in the environmental sense and YES in the

genetic sense

Experience and brain development

Use it or lose it, especially early on

Peer influence Parents are necessary for early childhood survival –

peers are necessary for lifelong survival

Peers are who we play with, work with, and eventuallymate with



Cultural Influence

Culture

The behaviors, ideas, attitudes, and traditions

shared by a large group of people Norms: the rules for accepted and expected

behavior (based on group membership)

Regardless of the cultural norms of a group, most

are very successful at raising children

One important consideration is that while thereare significant cultural differences present, weare still more alike than we are different



Gender – Biologically Speaking

Until the 7th week of pregnancy, all babies arefemale

It’s the activation of testosterone in a fetus thathas the XY pair of chromosomes that triggersmale organ production

In the fourth & fifth months, different brainpatterns develop due to different levels oftestosterone and ovarian hormones



Gender – Socially Speaking

Gender roles

The expectations about how men and women

behave In nomadic cultures, there is minimal gender role

occurrence

Boys and girls experience the same upbringing

In agricultural societies (of which ours originated),there are strict gender role structures in place

Most of our gender identity is acquired throughsocial learning

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