Chapter 4: Nature, Nurture, Human Diversity (Part 1)

Eliza Kronenberger, Kayla Russell, Abby Lagunov

A biological aspect of taste that humans prefer is the taste of sweets.

We start to fear strangers at around 8 months old.

3 universal behaviors of humans:

-dancing/feasting

-singing/worshipping

-playing sports/games

Behavior Behavior Genetics/EnvironmentGenetics/Environment

Study differences and weigh effects in the interplay of heredity and the environment.

Cell NucleusCell Nucleus Every cell nucleus in the body contains a

genetic master code for the entire body.

Definitions:Definitions: DNA: Complex molecule containing genetic

information that makes up chromosomes.

Chromosome: Threadlike structures made of DNA molecules, contain genes.

Genome: Complex instructions for making an organism, consisting of all genetic material in an organism’s chromosomes.

““We shared half our We shared half our genes with the genes with the

banana.”banana.” Proves that slight variation change in

genetics causes vast differences.

Types of TwinsTypes of Twins Identical Twins: Twins who develop from a

single fertilized egg, splits in 2 creating 2 genetically identical organisms.

Fraternal Twins: Develop from separate fertilized eggs- genetically no closer than ordinary brothers/sisters, but share fetal environment.

Fraternal TwinsFraternal Twins Fraternal twins are not any more similar

than an ordinary brother/sister.

Alzheimer’s DiseaseAlzheimer’s Disease If a person has Alzheimer’s disease, an

identical twin has a 60% chance of getting this disease. A fraternal twin has a 30% chance.

Matt McGue and David Matt McGue and David Lykken Study (1992)Lykken Study (1992)

Followed divorce rates of 1,500 same-sex, middle-aged twin pairs.

Results: Fraternal twin who is divorced- odds of divorce go up 1.6x (compared to not divorced twin)

Identical twin who is divorced- odds of divorce of other twin go up 5.5x

Importance of GenesImportance of Genes Genes do not matter in explaining individual

differences.

Quote: BouchardQuote: Bouchard “In some domains it looks as though our

identical twins reared apart are… just as similar as identical twins reared together. Now that’s an amazing finding and I can assure you none of us would have expected that degree of similarity.”

Even if twins are separated, biologically (with genes) interests are similar.

Bouchard’s Critics Bouchard’s Critics TheoryTheory

Separated fraternal twins do not exhibit similarities comparable to those of separated identical twins.

Twin StudiesTwin Studies Twin study results give us a greater

appreciation for genetic influences.

Genetic/Environmental Genetic/Environmental RelativesRelatives

Genetic- Biological parents/siblings

Environmental- adoptive parents/siblings

Does environment Does environment impact personality?impact personality?

Adoptees more similar to biological parents than to adoptive parents.

Quote:Quote: “Mom may be holding a full house while Dad

has a straight flush, yet when Junior gets a random half of each of their cards his poker hand may be a loser.”

Child is not guaranteed the best traits of each parent, but gets a random selection… No genetic legacy!

Adopted ChildrenAdopted ChildrenMost adopted children thrive because…

-Attatched to adoptive parents

Many score higher than biological parents on an intelligence test

Benefits of AdoptionBenefits of Adoption Children grow up happier

More self-giving than average

TemperamentTemperament A person’s characteristic emotional reactivity and intensity.

TemperamentTemperament Temperament persists over time.

TemperamentTemperament Biologically rooted temperament helps form

our enduring personality: one form of a gene that regulates the neurotransmitter serotonin predisposes fearful temperament and inhibited child.

HeritabilityHeritability Proportion of variation among individuals

that we can attribute to genes. The heritability traits may vary.

Environment Environment SimilaritiesSimilarities

As environments become more similar, heredity (as a source of differences) become more important.

Self Regulating GenesSelf Regulating Genes Genes react, rather than acting.

Eating DisordersEating Disorders Human differences result from both genetic

and environmental influences.

For example, eating disorders are genetically influenced- some people are at more of a risk than others.

Gene-Environment Gene-Environment InteractionInteraction

Genes and experiences are both important, but they interact.

Interaction: Interplay that occurs when the effect of one factor (such as the environment) depends on another factor (heredity).

““Heredity deals the Heredity deals the cards; environment plays cards; environment plays

the hand.”the hand.” Biology starts off a person’s life- personality

develops and changes them from the society around them.

Nature/NurtureNature/Nurture Think “Nature VIA Nurture” instead of

“Nature Vs. Nurture”.

Molecular GeneticsMolecular Genetics Subfield of biology that studies molecular

the molecular structures and functions of genes.

Molecular Behavior Molecular Behavior GeneticsGenetics

Goal: to find some of the many genes that influence normal humane traits, such as baby weight, sexual orientation, extraversion, and also explore mechanisms that control gene expression.

““Missing Women”Missing Women” Men/boys are favored in India and China...

Girl children are often killed or given away. This is a problem now because there are too many boys in this area and a shortage of girls.

Evolutionary Evolutionary PsychologistsPsychologists

The study of the evolution of behavior and the mind, using principles of natural selection.

Natural-SelectionsNatural-Selections The principle of the survival of the fittest

Belyeav & Trut: Fox Belyeav & Trut: Fox StudyStudy

In this study, wild foxes were collected and the most tame of these were mated with one another. Over a few decades, these animals became completely domesticated.

MutationsMutations A random error in gene replication that leads to a change

Universal ActionsUniversal Actions Example: A loved one of any culture in the

world is greeted in the same way.

Predisposition to Predisposition to TastesTastes

Humans are predisposed to love sweet and fatty tastes.

Outcome? Outcome? This love of sweet/fatty foods has led to obesity in Western cultures.

Harms of Industrial Harms of Industrial RevolutionRevolution

Our bodies are not wired for this type of world- with such mass productions.

It has also adjusted us to live by a clock schedule.

DarwinDarwin All current scientists agree with Darwin’s

ideas.

Two Questions of Two Questions of Evolutionary Evolutionary

Psychologists?Psychologists? What are the mental differences between men and women?

How do genes shape our current environment? (Nature VIA Nurture)

Gender difference in Gender difference in SexualitySexuality

Men have a much stronger sex drive than women.

Pryor’s study on Pryor’s study on attitudes towards attitudes towards

casual sex:casual sex: Discovered that about 58% of men favored casual sex,

while only 34% of women did.

Fischstein’s study on Fischstein’s study on sexual thoughts:sexual thoughts:

About 46% of men think about sex throughout the whole day.

This is about the same for both Canadians and Americans.

3 Differences between 3 Differences between gay men and lesbian gay men and lesbian

women:women: Gay men report more interest in un-committed sex

compared to women

More responsive to sexual stimuli

More concerned with physical attractiveness

Clark and Hatfield’s Clark and Hatfield’s Study:Study:

Had university students wander around the campus and say that other random students were attractive.

¾ of men agreed: 50% to a cup of coffee, 75% to sex

No women agreed.

Approaches to sex:Approaches to sex: Men: Approach is more recreational

Women: Approach is more relational

4 characteristics that 4 characteristics that men find attractive:men find attractive:

Healthy women

Fertile (young)

Smooth skin

Youthful shape

Women preferences of Women preferences of men: men:

13 year old boy 17/18 year old girl

25 year old boy Same age girl

50 year old boy Younger women

2 Characteristics that 2 Characteristics that women find attractive:women find attractive:

Being affluent/wealthy

Dominant

Long-Term MatesLong-Term Mates Evolutionary psychologists believe that women prefer long term

mates because of their investments in joint offspring.

Roney’s Study on Roney’s Study on Women and Baby Women and Baby

Pictures:Pictures: In this experiment, women skillfully discerned which men

most liked looking at baby pictures, and they rated those men higher as potential long-term mates.