Chapter 3 the Nature and Nurture of Behavior

Chapter 3 the Nature and Nurture of Behavior

Chapter 4 In-class Notes, ’16 – Nature, Nurture, and Human Diversity

Behavior genetics, nature, nurture

Nucleus: book; chapters -- chromosomes (paper: DNA); words – genes(expressed or inactive); letters – nucleotides

-thehuman genome – only slight differences, traits are gene complexes

-twin studies – identical (monozygotic) versus fraternal (dizygotic) – differences in heredity, environment, extraversion versus introversion, neurotic AKA reactive, unstable vs. stable

-Thomas Bouchard study – identical twins raised apart (“the Jims”)

-Biological vs. Adoptive Relatives: “the stunning finding”:

-adoptive homes, parents do influence:

temperament:

heritability:

-why it can vary from study to study

-individual differences NOT equal to group differences

-nature enablesnurture -- gene-environment interaction

-The New Frontier: molecular behavior genetics / issues, epigenetics, self-regulating, epigenetic marks

Evolutionary Psych: Understanding Human Nature

Evolutionary psych, natural selection, breeding dogs and foxes, mutations;

one possible explanation for similarities -- tastes, behavior, sexuality, gender differences, fears, sex differences between men and women

-evolutionary sexuality explanation:

MEN:

WOMEN:

-critiquing the evolutionary perspective: social scripts

Culture, Gender, and Other Environmental Influences: interactions

-prenatal environment

-experience and brain development; Rosenzweigexperiment; critical periods, pruning

-parents’ influence:

-peer influence: what, extremes

-culture influence: norms, personal space, individualism versus collectivism (table 4.2 pg. 158),

-cultural neuroscience

Gender Development: men versus women on: aggression, social power, connectedness;

-male answer syndrome, interdependence, side-by-side, face-to-face, tend and befriend, independence

Nature: X chromosome, Y chromosome, testosterone – effects; puberty – primary sex characteristics, secondary sex characteristics, menarche, disorder of sexual development / sex reassignment surgery

Nurture: gender role, gender identity

how do we learn them?, social learning theory, gender-typing , androgyny,gender schemas,gender expression – androgyny, transgender, transsexual, sexual orientation

Reflections: both, but not just genes and culture: individual choice, faith and reason, awe….

Chapter 4 In-class Notes, ’16 – Nature, Nurture, and Human Diversity (with spaces)

Behavior genetics, nature, nurture

Nucleus: book; chapters -- chromosomes (paper: DNA); words – genes(expressed or inactive); letters – nucleotides

-the human genome – only slight differences, traits are gene complexes

-twin studies – identical (monozygotic) versus fraternal (dizygotic) – differences in heredity, environment, extraversion versus introversion, neurotic AKA reactive, unstable vs. stable

-Thomas Bouchard study – identical twins raised apart (“the Jims”)

-Biological vs. Adoptive Relatives: “the stunning finding”:

-adoptive homes, parents do influence:

temperament:

heritability:

-why it can vary from study to study

-individual differences NOT equal to group differences

-nature enablesnurture -- gene-environment interaction

-The New Frontier: molecular behavior genetics / issues, epigenetics, self-regulating, epigenetic marks

Evolutionary Psych: Understanding Human Nature

Evolutionary psych, natural selection, breeding dogs and foxes, mutations;

one possible explanation for similarities -- tastes, behavior, sexuality, gender differences, fears, sex differences between men and women

-evolutionary sexuality explanation:

MEN:

WOMEN:

-critiquing the evolutionary perspective: social scripts

Culture, Gender, and Other Environmental Influences: interactions

-prenatal environment

-experience and brain development; Rosenzweig experiment; critical periods, pruning

-parents’ influence:

-peer influence: what, extremes

-culture influence: norms, personal space, individualism versus collectivism (table 4.2 pg. 158),

-cultural neuroscience

Gender Development: men versus women on: aggression, social power, connectedness;

-male answer syndrome, interdependence, side-by-side, face-to-face, tend and befriend, independence

Nature: X chromosome, Y chromosome, testosterone – effects; puberty – primary sex characteristics, secondary sex characteristics, menarche, disorder of sexual development / sex reassignment surgery

Nurture: gender role, gender identity

how do we learn them?, social learning theory, gender-typing , androgyny, gender schemas, gender expression – androgyny, transgender, transsexual, sexual orientation

Reflections: both, but not just genes and culture: individual choice, faith and reason, awe….

Chapter 3 -- The Nature and Nurture of Behavior – complete notes

Version 1

Genes: Our Bio Blueprint

Body cells:

-DNA

-chromosomes

-nucleotides

Located inside the nucleus (library) of each cells in the human body are the chromosomes (46 books-23 from your mother’s egg and 23 from your father’s sperm). This threadlike structures of chromosomes are composed of DNA (deoxyribonucleic acid) molecules. Segments of the DNA, called genes (words) are the biochemical units of heredity that make up the chromosomes. Genes are also capable of synthesizing particular proteinsthe building blocks of our physical development. Each genes are composed of biochemical nucleotides (letters - ATCG). The smallest human chromosome (Y) has 50 million nucleotide; the largest chromosomes has 250 million. Around 3.1 billion paired nucleotides define the genes that determines our individual biological development.

--Human genome researchers have discovered the common sequence of the 3.1 billion letters within the human DNA.

--human genomes complete the instructions for making an organism. It consists of all the genetic material in its chromosomes. The human genome has 3 billion weakly bonded pairs of nucleotides organized as coiled chains of DNA.

--Human traits are influenced by gene complexes many genes acting in concert (height, length of bones etc.)

Evolutionary Psych:

-the study of the evolution of behavior and the mind, using principles of natural

selection.

-helpful for understanding the reproductive advantages of human aggression.

Breeding selection (microevolution)- selective breeding that could change certain traits, or emphasize certain traits that are already in the DNA.

Natural selection has favored genes that designed both behavioral tendencies and information-processing systems that solved adaptive problems faced by our ancestors, thus contributing to the survival and spread of their genes. It is the principle that, among the range of inherited trait variation, those that lead to increased reproduction and survival will most likely be passed on to succeeding generations.

Mutation - a random error in gene replication that leads to a change in the sequence of nucleotides; the source of all genetic diversity.

Of our relatively few genetic differences, only 6% are genetic differences among races. Only 8% are genetic differences among groups within a race. The restover 85%are individual variations within local groups.

Over generations, the genes of individuals not so disposed tended to be lost from human gene pool. As further mutations occurred, genes providing an adaptive edge continued to be selected. The result, say evolutionary psychologists, is behavioral tendencies and a capacity for thinking and learning that prepared our Stone Age ancestors to survive, reproduce, and send their genes into the future. Nature selected the fittest adaptations, which also include the human diversity that suits Arctic and equatorial dwellers to thrive in their distinct environments.

--Evolutionary psychologists study how natural selection has shaped our behavioral tendencies. They reason that if organisms vary, if only some mature to produce surviving offspring, and if certain inherited behavior tendencies assist that survival, then nature must select those tendencies. They believe this helps explain gender differences in sexuality.

Sexuality

Gender - in psychology, the characteristics, whether biologically or socially influenced, by which people define male and female.

Gender differences in attitudes extend to differences in behavior. Casual hit-and-run sex is most frequent among males with traditional masculine attitudes (Pleck & others, 1993). Men also have a lower threshold for perceiving warm responses as a sexual come-on. In study after study, men more often than women attribute a woman’s friendliness to sexual interest (Abbey, 1987; Johnson & others, 1991). Misattributing women’s cordiality as a come-on helps explain men’s greater sexual assertiveness (Kendrick & Trost, 1987). The unfortunate results can range from sexual harassment to date rape.

Evolutionary Explanation :biologists explains that while a woman incubates and nurses an infant, a male can spread his genes through other females. Our natural yearnings are our genes’ of reproducing themselves.

MEN: In 37 cultures judge women as more attractive if they have a youthful appearance. Evolutionary psychologists say that men drawn to healthy, fertile-appearing womenwomen with smooth skin and a youthful shape suggesting many childbearing year to comehave stood a better chance of sending their genes into the future.

WOMEN: also feel Attracted to healthy looking mean, but especially to those who seem mature. Dominant, bold, and affluent (Singh, 1995). Such attributes, say the evolutionary psychologists, connote a capacity to support and protect (Buss, 1996, 2000; Geary, 1998).

Some 150 studies of gender and risk taking reveal that in 14 of 16 realms (including intellectual risk taking, physical skills, smoking, and sex) men are the greater risk takers (Byrnes & others, 1999). In explaining why 16- to 14-year old men show more bravadoand are therefore nearly three times more likely than young women to die in auto crashes.

Criticism:

-- If men were uniformly loyal to their mates, might we not reason that the children of committed, supportive fathers more often survived to perpetuate genes? Might not men also be better off bonded to one womanboth to increase the otherwise slim odds if impregnation and to keep her from the advances of competing men? Might not a ritualized bonda marriagealso spare women from chronic male harassment?  Evolutionary explanations for why humans tend to pair off monogamously.

--Cultural expectations bend the genders, and what’s attractive varies somewhat with time and place.

--Some gender differences in mate preferences do seem universal across cultures. But again, critiques questions whether such gender differences may to some extent be byproducts of a culture’s social and family structures.

--Social consequences of evolutionary psychology: does it suggest a genetic determinates that strikes at the heart of progressive efforts to remake society (Rose, 1999)? Does it undercut ethical theory and moral responsibility? Could it be used to rationalize?

Critics maintain that evolutionary psychologists make too many hindsight explanations.

Behavior genetics: Predicting Individual Differences

Behavior genetics - the study of the relative power and limits of genetic and environmental influences on behavior.

Behavioral geneticists more intensively assess our differences from one another. How much are our differences shaped by our differing genetic blueprints? And how much by our environmentevery external influence, from maternal nutrition while in the womb to social support while nearing the tombreacting to our genetic traits? To what extent are we formed by our upbringing? Our culture? And by our current circumstances?

Twin Studies

-Genetic influence between Identical vs. Fraternal Twins:

Identical twins - twins who develop from a single fertilized egg that splits in two, creating two genetically identical organisms. They are nature’s own human clonesindeed, clones who share not only the same genes but the same conception, uterus, birth date, and cultural history.

Identical twins are more similar than Fraternal twins on both extraversion (outgoingness) and neuroticism (emotional instability/temper).

A person whose identical twin has Alzheimer’s disease has a 60% risk of sharing the disease.

If you have an identical twin who has divorced, the odds of your divorcing go up 5.5 times.

Identical twins are more similar than fraternal in many ways-in abilities, personality traits, and interests.

Identical twins who parents treated them alike were not psychologically more alike than identical twins who were treated less similarly. Research on 336 Canadian twin pairs also shows a substantial genetic influence on attitudes toward reading, organized religion, playing sports, and assisted suicide (Olson & others, 2001).

Fraternal twins - twins who develop from separate eggs. they are genetically no closer that brothers and sisters, but they share a fetal environment. They are genetically no more similar than an ordinary brothers and sisters.

Fraternal twins risk only 30% chance of sharing Alzheimer’s disease if one twin is affected by the disease.

If your fraternal twin has divorced, then the chance of your divorcing up is 1.6 times, (compared to the odds with a not-divorced twin).

-Thomas Bouchard study – identical twins raised apart (the Jims)

When the twins were tested measuring their intelligence, personality, heart rate, and brain waves, the Jim twinsdespite 38 years of separationwere virtually alike as the same person tested twice.

--Moreover, separated twins shared an environment for at least their first 9 months. They share an appearance, and the responses it evokes. And adoption agencies tend to place separated twins in similar homes. When environment are similar, the impact of environment looks smaller relative to heredity.

Adoptions studies

Adoption creates two groups of relatives:

1. The adoptee’ genetic relatives (biological parents and siblings

2. Environment relatives (adoptive parents and siblings).

For any given trait we can therefore ask whether adopted children are more like their adoptive parents, who contribute a home environment, or their biological parents who contributed their genes (nature vs. nurture). While sharing the same home environment, do adopted siblings come to share traits?

Stunning findings:

Adoptee’ traits bear more similarities to their biological parents to their care giving adoptive parents.

Two adopted children reared in the same home are no more likely to share personality traits with one another than with the child down the block.

Adoption studies show that, although personalities of adopted children do not much resemble those of their adoptive parents, adoption matters (Brazens & Schechter, 1990).

A pair of adopted children or identical twins will have more similar religious beliefs if reared in the same home (Kelley & De Graaf, 1997; Rohan & Zanna, 1996).

In adoptive home, child neglect an abuse and even parental divorce are rare. Despite a somewhat greater risk of psychological disorder, most adoptive children thrive, especially when adopted as infants (Benson & others, 1994;Wierzbibki, 1993).

Adoptee scores higher than their biological parents on intelligence tests.

7 out of 8 report feeling strongly attached to one or both adoptive parents.

They generally become happier and more stable people than they would have been in a stressed or neglectful environment.

Clearly, to benefit from adoption, children need not have personalities that resemble those of their adoptive parents.

Nature:

Temperament Studies

Physiological test reveal that anxious, high-strung infants have high and variable heart rates and reactive nervous system (Kagan & others, 1992). They become more a physiologically arouse when facing new or stranger situations. Compared with fraternal twins, identical twins have more similar temperaments. Such evidence adds to the emerging conclusion that our biologically rooted temperaments help form our enduring personalities (McCrae & others, 2000; Rothbart & others, 2000).

temperament- a person’s characteristic emotional reactivity and intensity.

Heritability

Using the twin and adoption methods, behavior geneticists can mathematically estimate the heritably of any traitthe extent to which variation among individuals can be attributed to their differing genes. Heritability refers instead to the extent to which differences among people are attributed to genes. As environment become more similar, heredity as a source of differences necessarily becomes more important. The heritability of a trait may vary, depending the on the range of populations and environments studies.

Heritable individual differences need not imply heritable group differences. If some individuals are genetically disposed to be more aggressive than others. Putting people in a new social context can change their aggressiveness.

Nature enables Nurture--Genes and environmentnature and nurturework together like two hand clapping, with the environmet reacting to and shaping what nature predisposes. For psychological traits, human difference are nearly always the result of both genetic and environmental variations.

Gene-Environment Interaction

Our genetically influenced traits evoke significant responses in other. Thus, an aggressive child may be yelled at by a teacher who talks warmly to the child’s model classmates. This helps explains my identical twins rear in different families recall their parents’ warmth as remarkably similar. Fraternal twins recall their early family life more differentlyeven if rear in the same family. Moreover, as we grow older we also select environments well suited to our natures.

We are the product of a cascade of interactions [the dependence of the effect of once factor (such as environment) on another factor (such as heredity).] between our genetic predispositions and our surrounding environments. Our genes affect how people reacts to and influence us.

The New Frontier: Molecular Genetics - sub field of biology that studies the molecular structure and function of genes.

Molecular genetics quest to find the specific genes that influence behavior. In dozens of labs worldwide, molecular geneticists are teaming with psychologists in search of genes that put people are risk for genetically influenced disorders. Genetic tests can now reveal who is at risk for at least a dozen diseases. Aided by inexpensive new techniques for scanning relevant DNA snips, medical personnel may soon be able to give would-be parents a read-out on how their fetus’ genes differ from the normal pattern and what this might mean. with this benefit come risks of labeling people. Might such labeling lead to discrimination or self-fulfilling prophecies? Prenatal screening also poses other ethical issues. Blueprints for “designer babies” are, of course, constrained by the reality that it takes many genes to influence behavior in combination with complex environments. By “selecting” our certain traits, we may deprive ourselves of future Handels, and van Goghs, Churchills and Lincolns and Dickinsontroubled people all.