Behavioral Genetics and Gender - PowerPoint Presentation

Slide1

Behavioral Genetics and Gender

AP PsychologyMyers, Ch. 3Slide2

What Makes You You

?Nature

- Genetics

Genes

Heredity

Nurture

– Environmental circumstances

Culture

Parents

PeersSlide3

Behavioral Genetics

The study of relative power and limits of genetic and environmental influences on behaviorStudies the interplay of nature and nurtureSlide4

Nature

Biological InfluencesSlide5

Biological Influences

Genes

– units of DNA that carry hereditary information

DNA (deoxyribonucleic acid)

–contains the genetic info to make chromosomes

Chromosomes

– threadlike structures made of DNA that contain the genes (46, 23 pairs)Slide6

Biological Influences

Genome – the complete genetic instructions for making an organism (shared genetic profile)

As humans we share 99.9% of the same DNA, but the 0.01% difference is what makes us all different.

Humans and chimpanzees share about 95% of the same DNA – close cousins, but clearly very different.Slide7

Identical

twins

Fraternal

twins

Same

sex only

Same or

opposite sex

Twin Studies – Nature’s Perfect Experiment

Allows scientists to separate nature and nurture influences

Identical twins

–

one egg split in two

 genetically identical

Differences are due to environment

Fraternal twins

–

2 eggs at the same time



genetically similar like any other sibling relationship

Differences due to genetics and environment

Identical twins are MUCH MORE SIMILAR in ALL AREAS than fraternal twins.

Intelligence

Predisposition to behaviors

Temperament

– emotional reactivity, influences personality (constant from infancy to adulthood)Slide8

Twin Studies – Separating Nature and Nurture

Identical twins separated at birth share overwhelming similarities later in life.

Fraternal twins share some similarities but not close to those of identical pairs.

Critics – place two strangers in a room and study them



you will find dozens of similarities and coincidences as wellSlide9

Twin Studies – Separating Nature and NurtureSlide10

Heritability

The extent to which genetic individual differences contribute to individual differences in observed behavior

“How much is this trait influenced by nature, rather than nurture?”

Example - Mark Twain’s Idea…

10 unrelated boys are raised until age 12 in barrels, thus experiencing exactly the same environment.When given an IQ test at age 12, their results will be lower than most 12 year old boys but relatively similar.

100% of any differences would be attributed to genetic influences and heredity

 Therefore, the heritability of intelligence would be 100% in this situation.

Heritability percentages change as environmental and genetic factors interact.

As environments become more similar, heritability increases.

As environments become more diverse, heritability decreases.Slide11

Nurture VIA

Nature

Diathesis-stress model

Behaviors are a result of both biological (nature) factors and life experiences (nurture).

Interaction

the effect of one factor (eg: environment) depends on another factor (eg: heredity)Some people are genetically predisposed/vulnerable to certain conditions, which are then triggered by external circumstances.

EX: Schizophrenia

Nature

– family studies show that schizophrenia is in part heritable (family studies, 1/10 if parent has disease; 1/100 if not)

Nurture

– stressful or traumatic events can trigger the onset of schizophrenia

Other examples: obesity, heart disease, alcoholism, eating disordersSlide12
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Evolutionary Psychology

Study of evolution of behavior and the mindHow are we all alike?

Focuses on natural selection

Natural selection

–

traits that enable survival and reproduction will be passed to succeeding generationsCertain fears may be innate – humans who stayed away from dangerous animals and plants survived (those who did not were killed – no reproductionChanges in traits over time are due to genetic mutations

While the theory of evolution is religiously contested, virtually every scientist will agree with Darwin’s general theory evolution through natural selection – basis of biologySlide14

Evolutionary Theories on Sexuality

Ever wonder why women may tend to view sexual activity in terms of relationships while men may tend view sexual activity in terms of recreation…

Historically, men and women worked together to ensure the survival of the most offspring.

Women chose wisely to mate with one or a few strong healthy men.

Men chose to mate with many women to increase the possibility of healthy children.Slide15

Evolutionary Theories on Sexuality

What do men and women consider “attractive?”Men – youthfulness and an hourglass figure (waist 1/3 narrower than hips.

Eludes to past generations of men looking for healthy women to increase the chance of the offspring survival) – a woman appears more fertile if their waist is 1/3 narrower than their hips

Women – youthful/healthy looking, mature, dominant, bold, affluent, and commitment-oriented

Eludes to past generations of women needing strong healthy men to support and protect mother/childSlide16

Critics of the Evolutionary Perspective

Critics of evolutionary psychology –

“Mental processes and behaviors are also influenced by culture and society.”

Culture dictates our choices, not just evolution.

Too much emphasis on nature, while ignoring nurture.

Going back to sexuality as an example…

What men and women desire in each other changes with culture and society

eg: Marilyn Monroe of the 1950s was considered the quintessential sexy woman, however she weighed much more than what is considered beauty in the 2000s

Culture dictates our mating choices, not just evolution

Culturally accepted in Western societies that humans pair off monogamously, unlike thousands of years ago when men had sex with various women to ensure the survival of their offspring. Slide17

Nurture

Environmental InfluencesSlide18

Prenatal Development

Mother's placenta gives fetus nourishment, as well as can transfer toxic agents.Why is this a nurture influence and not a nature influence?Slide19

Impoverished

environment

Rat brain

cell

Rat brain

cell

Enriched

environment

Experience and Brain Development

Experience reflects on brain size and complexity (

Rosenzweig

rat experiment)

Babies who are handled (especially premature babies) develop faster than nonhandled babies. Evidence is found in prenatal units - mothers hold premature babies to speed development and growth.

Use it or lose it – stimulation is essential for brain development and maintenance.

"Our genes dictate overall brain architecture, but experience directs the details."Slide20

Parental and Peer Influence

Parents

Peers

LONG TERM INFLUENCE

abused more likely to abuse, political attitudes, religious beliefs, personal manners, habits

education, discipline, responsibility, orderliness, charitableness, and ways of interacting with authority figures.

Other environmental factors are at play as well, so parents can’t get 100% credit or blame.

SHORT TERM INFLUENCE

Conformity, desire to “fit in” in the short-term

learning cooperation, desire for popularity, inventing styles of interaction among people of the same age.

Parents and family have more long term influenceSlide21

GENDER DEVELOPMENT

A Study into Nature and Nurture InfluencesSlide22

Sex vs

GenderNature

Nurture

Sex

– biological category for males and females

Gender

– social category influenced by culturally assumed characteristics for males and femalesSlide23

Sex (Nature)

XX – chromosome pair for biological femaleXY

– chromosome pair for biological maleSlide24

Sex (Nature)

Testosterone

Sex hormone, larger amounts in males and stimulates…

growth of male sex organs in the fetus

development of male sex characteristics during puberty

Biology affects our assumption of gender

Ex: botched circumcision + female upbringing (estrogen supplements,

extreme female genderfication) = gender identity confusionSlide25

Gender (Nurture)

Role - a set of expectations/norms about a

social

position

Gender roles – expectations about males and females should behave

Culturally boundTime/context specificSlide26

Gender (Nurture)

Gender Identity - one's sense of being male or femaleDevelops early in life (before puberty)Slide27

Theories on Gender

SOCIAL LEARNING THEORY (of Gender) - children learn social behavior by observing, imitating, and then by being

rewarded or punished

children learn gender roles from parents and peers by observing and imitating behaviors and then experiencing a reward or punishment

eg: "Big boys don't cry." - a young boy is socially punished for crying because expressing emotion (crying) is not associated with male gender roles

 diminished behavior - no more cryingSlide28

Theories on Gender

GENDER SCHEMA THEORY

-

Children form a

concept

about gender

and adjust behavior/thoughts accordingly

 view world with gender lens

Female schema – cooking, long hair, pink, teacher, skirt

Male schema – rough, blue, airplane pilot, pants, short hair

Constant modification

Assimilation

- interpreting new experiences in terms of existing schemas

Accommodation

- adapting current understandings/schemas to incorporate new informationSlide29

Observation then experience

Based on reward/punishment

Observation

Based on observation then schema creation/modification

Slide30

Gender and Social Connectedness

Females tend to be more interdependent and social - spend less time alone than malesBoys typically play together in large groups, while girls prefer smaller groups with intimate discussion

Men emphasize freedom and self-reliance

Women are more open to spirituality

Women are more intimate than men with friends

Men like doing activities that are side-by-side, while women prefer face-to-faceWomen are more likely to turn to others for support/help