Psych (Conclusion of Bio Approach Slides)

7/30/2019 Psych (Conclusion of Bio Approach Slides)

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Genes, Evolutionary

Psych, Twin andAdoption StudiesChap 3 Myers


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Genes: Our Codes for LifeChromosomes containing DNA (deoxyribonucleic

acid) are situated in the nucleus of a cell.


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Genes: Our Codes for Life

Segments within DNA consist of genes that makeproteins to determine our development.


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Genome

Genome is the set of complete instructions formaking an organism, containing all the genes inthat organism. Thus, the human genome makes

us human. We share 99.9 percent of our DNAwith every other human on earth.

Slight differences in DNA can determine whogets diseases, who is short or tall, or who is

depressed or happy.


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Evolutionary Psychology: UnderstandingHuman Nature

Evolutionary psychology studies why we as humansare alike. In particular, it studies the evolution of

behavior and mind using principles of natural selection.

Natural selection is an evolutionary process throughwhich adaptive traits are passed on to ongoing

generations because these traits help animals surviveand reproduce. Some mutations occur that give an

organism a competitive edge. This is then passed on.Ex. Sharks with keener than normal smell, Bull Moose

with large antlers, etc.


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Artificial SelectionBiologists like Belyaev and Trut (1999) were able to

artificially rear and domesticate wild foxes, selectingthem for friendly traits. These domesticated foxes arenow sold as pets.

Any trait that isfavored naturally or

artificially

spreads to futuregenerations.


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Human TraitsA number of human traits have been identified as a result

of pressures afforded by natural selection. EvolutionaryPsychology attempts to answer some of these questions:

Why do infants fear strangers when they become

mobile?

Why do people fear spiders and snakes and not

electricity and guns?

How are men and women alike? How and why domens and womens sexuality differ?


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Human Sexuality

Question (summarized) Male Female

Casual sex 58% 34%

Sex for affection 25% 48%

Think about sex everyday 54% 19%

Males and females, to a large extent, behave and thinksimilarly. Differences in sexes arise in regards to reproductivebehaviors. Men have a more recreational approach while

women more relational. Men also tend to misinterpret warmresponses from women as sexual interest

Gender Differences in Sexuality


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Natural Selection & Mating Preferences-Evolutionary Explanation

Natural selection has caused males to send theirgenes into the future by mating with multiplefemales since males have lower costs involved.

Men look for women whose waists are 1/3narrower than their hips.

However, females select one mature andcaring male because of the higher costsinvolved with pregnancy and nursing.

Looking for potential in long-term

relationship.


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Mating PreferencesMales look for youthful appearing females in

order to pass their genes into the future. Is thiswhy women spend their time and money on

their appearance? Females, on the other hand,look for maturity, dominance, affluence andboldness in males. Is this why men try to

establish their status and dominance?

Data based on 37 cultures.


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Behavior Genetics: Predicting IndividualDifferences

Behavior Geneticists study our differences

and weigh the relative effects of heredity andenvironment. Ask, how much are ourdifferences shaped by our genetic blueprints?And how much by our environment? Often

use twin studies and adoption studies.


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Twin Studies

Studying the effects of heredity and environment on two sets of

twins, identical and fraternal, has come in handy.

Identical- develop from a singlefertilized egg that splits in two.Genetically identical. Naturesown human clones.

Fraternal- develop fromseparate eggs. Genetically nomore similar than brothers orsisters.

Identical twins are much more

behaviorally similar thanfraternal twins are. Much morelikely to get divorced if youridentical twin does (5.5 timesmore likely) than if yourfraternal twin does (1.6 times

more likely).


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Separated Identical Twins

Separated Twins

Personality, Intelligence

Abilities, Attitudes

Interests, Fears

Brain Waves, Heart Rate

A number of studies compared identical twins reared

separately from birth, or close thereafter, and foundnumerous similarities.

Critics of separated twinstudies note that such

similarities can be foundbetween strangers.

Researchers point outthat differences between

fraternal twins aregreater than identical

twins. p.109-110 Myers


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Biological VersusAdoptive Relatives

Adoption studies, asopposed to twin

studies, suggest that

adoptees (who maybe biologicallyunrelated) tend to bedifferent from their

adoptive parents and

siblings.


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Adoptive StudiesAdoptive studies strongly point to the simple fact

that biologically related children turn out to bedifferent in a family. So investigators ask:

Do siblings have differing

experiences?

Do siblings, despite sharing

half of their genes, have

different combinations of the

other half of their genes?

Ultimate question: Does

parenting have an effect?


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Parenting

ParentingInfluencesChildrens

Attitudes,Values

Manners,Beliefs

Faith,Politics

Parenting does have an effect on biologically

related and unrelated children.


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Temperament and HeredityTemperament refers to a

persons stable emotionalreactivity (intense andfidgety or quiet and placid)and intensity. Exceptionallyinhibited and fearful 2-year-

olds often are still relativelyshy 8-year-olds; half willbecome introverted asadults. Identical twins

express similartemperaments, suggesting

heredity predisposestemperament.


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Gene-Environment Interaction

Genes can influence traits which affectresponses, and environment can affect gene

activity.

A genetic predisposition

that makes a child restlessand hyperactive evokes an

angry response from hisparents. A stressful

environment can triggergenes to manufacture

neurotransmitters leading

to depression.


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Gene-Environment InteractionGenes and environment affect our traits individually, but

more important are their interactive effects.

People respond differently to Jack Black than theydo to Robert Pattinson


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Neuroplasticity

The ability to develop and change in response to the

environment

Could see this with rats and how they develop thicker cortices

when exposed to an enriched environment

Handled preemie babies develop faster than those not touched Children benefit from learning an instrument or second language

earlier in life

Adults can still benefit from this as they build neural connections

and begin to master activities

Could even involve one brain area taking over the functions ofanother damaged brain area

Civil War amputees experienced phantom limb sensations as

sensory cortex space previously designated towards lost limb now

re-designated to other areas of the body.


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Experience and Brain Development

Early postnatal experiences affect braindevelopment. Rosenzweig et al. (1984) showed thatrats raised in enriched environments (with toys andother rats) developed thicker cortices than those inimpoverished environment (solitary confinement).


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Handled infant rats and premature babies respond

positively by gaining weight more rapidly and developfaster neurologically.

Touch and Massage Benefits


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Experience and FacultiesEarly experiences during development in humans shows

remarkable improvements in music, languages and the arts.

Experience preserves our activated connections while allowing ourunused connections to degenerate. This is why the pre-adolescent

can master several languages.


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Brain Development and AdulthoodBrain development does not stop when we reach

adulthood. Throughout our life, brain tissuecontinues to grow and change.

A well-learned finger-tapping task leads to

more motor cortical neurons (right) than baseline.

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