Chapter 4 - Nature, Nurture, and Human Diversity

What is Behaviour Genetics?

The study of the relative power and limits of genetic and environmental influences on behavior.

What do Behaviour Geneticists study?

They study our differences and weigh the effects and the interplay of heredity and environment.

What is Environment?

Every nongenetic influence, from prenatal nutrition to the people and things around us.

What is a Chromosome?

The threadlike structures made of DNA molecules that contain the genes.

It is composed of a coiled chain of the molecule DNA.

What are Genes?

The biochemical units of heredity that make up the chromosomes; segments of DNA capable of synthesizing proteins.

Small segments of the giant DNA molecules.

What is DNA?

A complex molecule containing the genetic information that makes up the chromosomes. (Deoxyribonucleic Acid):

When the mother's egg and the father's sperm unite, each contributes what?

23 chromosomes

Fraternal twins result when what happens?

Two eggs are fertilized by two sperm.

How do adoption studies seek to understand genetic influences on personality?

By evaluating whether adopted children's personalities more closely resemble those of their adoptive parents or their biological parents.

How many genes are in the human body?

20,000 - 25,000

What is Gene Expression?

It is the process by which the instructions in our DNA are converted into a functional product, such as a protein.

In other words...It is when the information stored in our DNA is converted into instructions for making proteins or other molecules.

It is a tightly regulated process that allows a cell to respond to its changing environment.

It acts as both an on/off switch to control when proteins are made and also a volume control that increases or decreases the amount of proteins made.

There are two key steps involved in making a protein, transcription and translation.

What does the nucleus of every human cell contain?

Chromosomes, each of which is made up of two strands of DNA connected in a double helix. Genes are DNA segments that, when expressed (turned on) direct the development of proteins that influence a person's individual development.

What is a Genome?

The complete instructions for making an organism, consisting of all the genetic material in that organism's chromosomes.

It is an organism's complete set of DNA, including all of its genes. Each one contains all of the information needed to build and maintain that organism. In humans, a copy of the entire genome—more than 3 billion DNA base pairs—is contained in all cells that have a nucleus.

When the mother's egg and the father's sperm unite, each contributes 23 ______________.

Chromosomes

What are Identical Twins?

Monozygotic twins; develop from a single fertilized egg that splits in two, creating two genetically identical organisms.

They have the same genes, but not always the same number of copies of those genes.

They share a placenta during prenatal development, but one of every three sets has separate placentas which could contribute to identical twin differences.

What does the variation of genes in identical twins help explain?

Why one twin may have a greater risk for certain illnesses and disorders; including schizophrenia.

What are Fraternal Twins?

Dizygotic Twins; develop from separate fertilized eggs. They are genetically no closer than ordinary brothers and sisters, but they share a prenatal environment.

If a twin is diagnosed with autism spectrum disorder, is the other twin at risk of the same diagnosis?

Yes, shared genes can share experiences. An identical twin has a 3 in 4 risk of being similarly diagnosed. A fraternal twin has a 1 in 3 risk.

How do researchers use twin and adoption studies to learn about psychological principles?

Researchers use twin and adoption studies to understand how much variation among individuals is due to genetic makeup and how much to environmental factors.

Some studies compare the traits and behaviors of identical twins (same genes) and fraternal twins (different genes, as in any two siblings).

They also compare adopted children with their adoptive and biological parents. Some studies compare traits and behaviors of twins raised together or separately.

What is Temperament?

A person's characteristic emotional reactivity and intensity.

What is Heritability?

The proportion of variation among individuals that we can attribute to genes. The heritability of a trait may vary, depending on the range of populations and environments studied.

The extent to which variation among individuals can be attributed to their differing genes.

An estimate of the extent to which differences (or variability) in traits among people can be explained by heredity.

What has one of the highest heritability estimates?

Height

What is Molecular Behaviour Genetics?

The study of how the structure and function of genes interact with our environment to influence behavior.

One goal of it is to find some of the many genes that together orchestrate complex traits such as body weight, sexual orientation, and impulsivity.

What is Molecular Genetics?

The study of the molecular structure and function of genes.

What is Epigenetics?

The study of environmental influences on gene expression that occur without a DNA change.

Studying the molecular mechanisms by which environments trigger or block genetic expression.

(Meaning "in addition to" or "above and beyond" genetics)

What is an Epigenetic Mark?

Often organic methyl molecules attach to part of a DNA strand. If a mark instructs the cell to ignore any gene present in that DNA segment, those genes will be "turned off"—they will prevent the DNA from producing the proteins normally coded by that gene.

What is Evolutionary Psychology?

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

They focus mostly on what makes us so much alike as humans. They use Charles Darwin's principle of natural selection to understand the roots of behavior and mental processes.

What is Natural Selection?

The principle that among the range of inherited trait variations, those contributing to reproduction and survival will most likely be passed on to succeeding generations.

What is the central idea behind Natural Selection?

-Organisms' varied offspring compete for survival.

-Certain biological and behavioral variations increase organisms' reproductive and survival chances in their particular environment.

-Offspring that survive are more likely to pass their genes to ensuing generations.

-Thus, over time, population characteristics may change.

What is Mutation?

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

How are Belyaev and Trut's breeding practices similar to, and how do they differ from, the way natural selection normally occurs?

Over multiple generations, Belyaev and Trut selected and bred foxes that exhibited a trait they desired: tameness.

This process is similar to naturally occurring selection, but it differs in that natural selection normally favors traits (including those arising from mutations) that contribute to reproduction and survival.

Would the heritability of aggressiveness be greater in Belyaev and Trut's foxes, or in a wild population of foxes?

Heritability of aggressiveness would be greater in the wild population, with its greater genetic variation in aggressiveness.

What is the Second Darwinian Revolution?

The application of evolutionary principles in psychology.

What is Sexual Over-Perception Bias?

The theory that men are more sensitive to cues regarding sexual opportunity than women, and thus men are more likely than women to misperceive sexual interest from opposite sex others.

Why are women choosier than men when selecting sexual partners?

-Genes; conceiving and protecting a fetus.

-Limitations on how many children can be conceived.

-Prefer signs of success and maturity, leading to support and protection.

-Women pair wisely.

What traits do men desire in a mate?

-Smooth skin, youthful shape - health.

-Genes; creating offspring.

-Small waists, symbolizing fertility.

What is a Social Script?

Culturally modeled guide for how to act in various situations.

How do evolutionary psychologists explain sex differences in sexuality?

Evolutionary psychologists theorize that females have inherited their ancestors' tendencies to be more cautious, sexually, because of the challenges associated with incubating and nurturing offspring.

Males have inherited an inclination to be more casual about sex, because their act of fathering requires a smaller investment.

What are the three main criticisms of the evolutionary explanation of human sexuality?

(1) It starts with an effect and works backward to propose an explanation.

(2) Unethical and immoral men could use such explanations to rationalize their behavior toward women.

(3) This explanation may overlook the effects of cultural expectations and socialization.

How do evolutionary psychologists use natural selection to explain behavior tendencies?

They seek to understand how our traits and behavior tendencies are shaped by natural selection, as genetic variations increasing the odds of reproducing and surviving in their particular environment are most likely to be passed on to future generations.

Some variations arise from mutations (random errors in gene replication), others from new gene combinations at conception.

Humans share a genetic legacy and are predisposed to behave in ways that promoted our ancestors' surviving and reproducing.

Charles Darwin's theory of evolution is an organizing principle in biology. He anticipated today's application of evolutionary principles in psychology.

How might an evolutionary psychologist explain male-female differences in sexuality and mating preferences?

Men tend to have a recreational view of sexual activity; women tend to have a relational view.

Evolutionary psychologists reason that men's attraction to multiple healthy, fertile-appearing partners increases their chances of spreading their genes widely.

Because women incubate and nurse babies, they increase their own and their children's chances of survival by searching for mates with the potential for long-term investment in their joint offspring

What is Interaction?

The interplay that occurs when the effect of one factor (such as environment) depends on another factor (such as heredity) - between our genetic predispositions and our surrounding environments.

In the Rosenzweig and Krech study, what happened to the brains' of rats raised in an enriched environment?

They developed significantly more cerebral cortex (relative to the rest of the brain's tissue) than the rats raised in the impoverished environment.

The rats in the impoverished environment showed less than optimal brain development, stifled neurons that were smaller with fewer dendrites.

The rats in larger social cages had heavier and thicker cortexes, more interconnections between neurons and larger neurons with more dendrites.

After 60 days in the enriched environment, the rats' brain weights increased 7 to 10 percent and the number of synapses mushroomed by about 20 percent.

What happens when you provide physical stimulation to human and animal infants?

"Handled" infants of both species develop faster neurologically and gain weight more rapidly.

Preemies who have had skin-to-skin contact with their mothers sleep better, experience less stress, and show better cognitive development 10 years later.

What is Plasticity?

The ability for nerve cells to change through new experiences. The brain's ability to adapt to change across the lifespan and to rewire itself after damage.

With every new experience, the brain changes in some way. As we experience an event or learn a new skill, new connections are formed between neurons, and connections that aren't needed anymore are eliminated.

It refers to the extraordinary ability of the brain to modify its own structure and function following changes within the body or in the external environment.

What is the Selection Effect?

The tendency to select out similar others and sort themselves into like-minded groups.

What is Culture?

The enduring behaviors, ideas, attitudes, values, and traditions shared by a group of people and transmitted from one generation to the next; language, preservation of innovation and division of labor.

It transmits the customs and beliefs that enable us to communicate, to exchange money for things, to play, to eat, and to drive with agreed-upon rules and without crashing into one another.

What is Peer Influence?

The impact exerted by a peer group on its separate members to fit in with or conform to group expectations by thinking, feeling, and acting in a like or approved way. Commonly referred to as peer-group pressure.

What is the Y Chromosome?

The sex chromosome found only in males. When paired with an X chromosome from the mother, it produces a male child.

What is the X Chromosome?

The sex chromosome found in both men and women. Females have 2 X chromosomes; males have 1; an X chromosome from each parent produces a female child.

What is Transgender?

An umbrella term describing people whose gender identity or expression differs from that associated with their birth sex.

What is Transexual?

A person who emotionally and psychologically feels that they belong to the opposite sex. They prefer to live as members of the other birth sex.

What is Sexual Orientation?

The direction of one's sexual attraction.

What is Gender Expression?

It refers to the ways in which we each manifest masculinity or femininity. It is usually an extension of our "gender identity," our innate sense of being male or female. Each of us expresses a particular gender every day - the way we style our hair, select our clothing, posture, and possessions.

What is Gender Identity?

Our sense of being male, female, or a combination of the two.

What is Social Learning Theory?

The theory that we learn social behavior by observing and imitating and by being rewarded or punished.

It assumes that we acquire our gender identity in childhood, by observing and imitating others' gender-linked behaviors and by being rewarded or punished for acting in certain ways.

What is Androgyny?

Displaying both traditional masculine and feminine psychological characteristics. The person exhibits both male and female behaviors, emotions, etc. This type of person is very much a mix of maleness and femaleness.

What are the benefits of androgyny?

These people are more adaptable, show greater flexibility in behavior and career choices, tend to be more resilient and self-accepting, and they experience less depression.

What is Gender Typing?

The acquisition of a traditional masculine or feminine role.

What is Gender Schema Theory?

A theory of gender development that combines social learning and cognitive learning theory.

Thus, gender roles are formed in part by observing others and learning from how others act, and from accomplishing different cognitive tasks specific to cultures that are done by men and by women.

What is a Gender Role?

It is generally defined as a set of attitudes, behaviors, and self-presentation methods ascribed to members of a certain biological sex.

A set of expected behaviors, attitudes, and traits for males or for females.

What is Male Answer Syndrome?

It is the tendency among men to give answers to questions whether they know anything about the subject or not, particularly when in the presence of women.

What are Child Rearing Practices?

It is the process of promoting and supporting the physical, emotional, social, financial, and intellectual development of a child from infancy to adulthood.

What is a Norm?

An understood rule for accepted and expected behavior. Norms prescribe "proper" behavior.

What is Culture Shock?

There remains no clear definition although various attempts have been made to "unpack" the definition:

-Strain due to the effort required to make necessary psychological adaptations.

-A sense of loss and feelings of deprivation in regard to friends, status, profession, and possessions.

-Being rejected by/and or rejecting members of the new culture.

-Confusion in role, role expectations, values,

-Surprise, anxiety, or disgust and indignation after becoming aware of cultural differences.

-Feelings of impotence due to not being able to cope with the new environment.

What is an Individualist?

Giving priority to one's own goals over group goals and defining one's identity in terms of personal attributes rather than group identifications.

An independent sense of "me," and an awareness of your unique personal convictions and values. They give higher priority to personal goals. They define their identity mostly in terms of personal traits. They strive for personal control and individual achievement.

They join groups but are less focused on group harmony and doing their duty to the group. Being more self-contained, they move in and out of social groups more easily. They feel relatively free to switch places of worship, switch jobs, or even leave their extended families and migrate to a new place. Marriage is often for as long as they both shall love.

What is a Collectivist?

Giving priority to the goals of one's group (often one's extended family or work group) and defining one's identity accordingly.

They have deeper, more stable attachments to their groups—their family, clan, or company.

They find satisfaction in advancing their groups' interests, even at the expense of personal needs. Preserving group spirit and avoiding social embarrassment are important goals.

They avoid direct confrontation, blunt honesty, and uncomfortable topics. They value humility, not self-importance. They hold back and display shyness when meeting strangers.

What are Group Identifications?

It is defined as member identification with an interacting group and is distinguished conceptually from social identity, cohesion, and common fate.

They provide a sense of belonging, a set of values, and an assurance of security in collectivist cultures.

What is Cultural Neuroscience?

They study of how neurobiology and cultural traits influence each other.

What is a Family Self?

A feeling that what shames the child shames the family, and what brings honor to the family brings honor to the self. Many Asian and African cultures value this strong sense.

How do individualist and collectivist cultures differ?

Individualists give priority to personal goals over group goals and tend to define their identity in terms of their own personal attributes.

Collectivists give priority to group goals over individual goals and tend to define their identity in terms of group identifications.

What is Sex?

In psychology, the biologically influenced characteristics by which people define males and females. The biological status, defined by chromosomes and anatomy.

What is Gender?

In psychology, the socially influenced characteristics by which people define men and women.

A culture's expectations about what it means to be male or female. It is the product of the interplay among our biological dispositions, our developmental experiences, and our current situations.

How many chromosomes does each human baby receive?

46; 23 from each parent. 45 are unisex.

What is Aggression?

In psychology, any physical or verbal behavior intended to harm someone physically or emotionally. Men are more likely to commit extreme violent acts.

What is Relational Aggression?

An act of aggression (physical or verbal) intended to harm a person's relationship or social standing. Women are slightly more likely than men to commit this.

What is Tend and Befriend?

It is a hypothesized stress response reaction that prompts humans to protect their own children, other children, people who are hurt or vulnerable, and to join humanitarian-oriented social groups that are intended to reduce human suffering.

This often viewed as a type of altruism that is believed to be more associated with women, and is believed to be the reason behind the female tendency to use friendship and peaceful techniques to solve problems rather than force.

How does biology influence gender?

In two ways:

1) Genetically - males and females have differing sex chromosomes.

2) Physiologically - males and females have differing concentrations of sex hormones, which trigger other anatomical differences.

What is a human's biological sex determined by?

The 23rd pair of chromosomes (2 sex chromosomes).

The mother's contribution to that chromosome pair was an X chromosome. From the father, the one chromosome out of 46 that is not unisex—either another X chromosome, making you female, or a Y chromosome, making you male.

About seven weeks after conception, a single gene on the Y chromosome throws a master switch, which triggers the testes to develop and to produce testosterone, the principal male hormone that promotes development of male sex organs.

Later, during the fourth and fifth prenatal months, sex hormones bathe the fetal brain and influence its wiring. Different patterns for males and females develop under the influence of the male's greater testosterone and the female's ovarian hormones.

What does Social Learning Theory propose?

That we learn gender identity—our sense of being male, female, or some combination of the two—as we learn other things: through reinforcement, punishment, and observation.

On average when do boys and girls begin puberty?

Girls around age 11, and boys around age 12.

What is an X Chromosome?

This chromosome is one of the two sex-determining chromosomes in many animal species, including mammals and found in both men and women.

Females have two; males have one. This chromosome from each parent produces a female child.

What is a Y Chromosome?

In mammals, this chromosome contains a gene SRY, a sex chromosome found only in males. When paired with an X chromosome from the mother, it produces a male child.

This chromosome in humans and other mammals also contain other genes needed for normal sperm production.

How do male and female chromosomes differ?

Males have one Y chromosome and one X chromosome, while females have two X chromosomes.

What is Testosterone?

The most important of the male sex hormones. Both males and females have it, but the additional testosterone in males stimulates the growth of the male sex organs during the fetal period, and the development of the male sex characteristics during puberty.

What is Puberty?

The period of sexual maturation, during which a person becomes capable of reproducing. In this two-year period of rapid sexual maturation, pronounced male-female differences occur.

What are Primary Sex Characteristics?

The body structures (ovaries, testes, and external genitalia) that make sexual reproduction possible.

What are Secondary Sex Characteristics?

The nonreproductive sexual traits, such as female breasts and hips, male voice quality, and body hair.

What are the female body changes at puberty?

The pituitary gland releasing hormones that stimulate the adrenal glands and ovaries which then both release hormones that stimulate:

-Underarm hair growth

-Breast development

-Enlargement of uterus

-Beginning of menstruation

-Pubic hair growth

What are the male body changes at puberty?

The pituitary gland releasing hormones that stimulate the adrenal glands and testes which then both release hormones that stimulate:

-Facial and underarm hair growth

-Larynx enlargement

-Pubic hair growth

-Growth of penis and testes

-Beginning of ejaculation

What is Spermarche?

The first male ejaculation.

What is Menarche?

The first female menstrual period.

What causes premature/early menarche?

Caused likely by following stresses related to father absence, sexual abuse, insecure attachments, or a history of a mother's smoking during pregnancy.

Why are girls developing earlier, sometimes before age 10, and reaching puberty earlier than in the past?

Suspected triggers include increased body fat, diets filled with hormone-mimicking chemicals, and possibly greater stress due to family disruption.

What is Disorder of Sexual Development?

An inherited condition that involves an unusual development of sex chromosomes and anatomy.

What causes disorder of sexual development?

When a fetus is exposed to unusual levels of sex hormones or is especially sensitive to those hormones, the individual may develop this disorder, with chromosomes or anatomy not typically male or female. A genetic male may be born with normal male hormones and testes but no penis or a very small one.

What is Sex Reassignment Surgery?

SRS is the surgical procedure (or procedures) by which a person's physical appearance and function of their existing sexual characteristics are altered to resemble that of their identified gender.

It is part of a treatment for gender dysphoria in transgender people. Related genital surgeries may also be performed on intersex people, often in infancy.

What is a hazard of sex reassignment surgery?

It can create confusion and distress among those not born with a disorder of sexual development.

What is a Role?

Social postition; a set of expectations (norms) about a social position, defining how those in the position ought to behave.

What are the Psychological Influences on Development?

-Gene-environment interaction

-Neurological effect of early experiences

-Responses evoked by our own temperament, gender, etc

-Beliefs, feelings and expectations