Name human traits that you believe to be universal.

• Communicate verbally and nonverbally• Enforce rules of etiquette• Show favoritism for in-group members (kin vs. non-kin)• Avoid incest, fear, snakes• Exchange gifts• Modesty in sexual behavior and bodily functions even if they don’t wear

clothes• Labor divided by gender• Men are more aggressive than women• Women provide more child care• All cultures have tools and tools to make tools• Beliefs about death and disease• Plan for the future• Taboos, and taboo utterances• Sanctions for crimes against society• Mechanisms for dealing with theft, murder, rape• Recognize marriage as the definition of socially recognized sexual access to

a fertile woman• Mimic, flirt, envy, empathize, joke, tease, dance, music• Myths, folklore, worldviews, poetry, attempts to control the weather

Was it Nature or Nurture?

• Not vs… rather, nature via nurture

• Over 70% of who we are is due to genetics– Active (expressed) vs. inactive

• What “turns on” genes to create protein molecules?

What separates us human to chimp or human to human?

Behavior Genetics: Predicting Individual Differences

Behavior Geneticists study differencesweigh relative effects of heredity/environment.

Genes: Our Codes for Life

Chromosomes containing DNA (deoxyribonucleic acid) are situated in

the nucleus of a cell.

Genes: Our Codes for Life

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

How/why do blue eyes happen?

• Blue eyes are recessive• Every person with blue eyes is related to one another• Common ancestry based in eastern Europe (6-10,000

years ago)– 99% of Estonians have blue eyes, 75% of Germans, 89% of

Danes– Genetic mutation affecting OCA2 gene

• Gene codes for protein P that deals with production of melanin

• Conclusion?– Blue eyes are not actually blue, they are a lack of brown– What is it called when the OCA2 gene has been completely

turned off?

Genome

Genome is the set of complete instructions for making an organism

containing all the genes in that organism. Thus, the human genome makes us human

Genetic predispositions• Genetically influenced traits

– Help explain our shared human nature and human diversity

Behavior Genetics and Evolutionary Psychology

• Transmission of hereditary characteristics is achieved by biological processes– Chromosomes carry information stored in

genes to new cells during reproduction– Cells of ovaries and testes produce eggs and

sperm which normally have 23 chromosomes• Of the 23 pairs of chromosomes, 22 are non-

sex chromosomes • XX (female) XY (male)

CONGRATULATIONS!!

• At fertilization, the chromosome from the egg and sperm recombine to form a zygote (fertilized egg) – with 46 chromosomes that will develop into a

new individual… aka you

• So yes… congratulations, at one point in your life, you can count yourself as a winner

Dominant vs. Recessive Genes

• A man with red hair (recessive) marries a woman with black hair (dominant) whose mother had red hair. What are the chances that their first child will have red hair? (Two chances in four.) Black hair? (Two chances in four.)

• A man and a woman both have brown eyes, but their first child has blue eyes. What are the chances that their second child will have blue eyes? (One chance in four—the odds of blue eyes is the same regardless of how many previous children already have blue eyes.)

The sex (not gender) of the new individual is determined by the sperm that fertilizes the egg

• Sperm carries X = female

• Sperm carries Y = male– Hermaphroditism is a condition that comes

from autosomal inheritance of genes• Autosomes are the 22 other non-sex

chromosomes

Chromosomes, Genes, and DNA

• Genes carried by chromosomes are the units of inheritance that are sequences of DNA

• The sequence of bases along a strand constitutes the genetic code– The genetic code gives instructions to perform a

specific function in the body (i.e. release this protein or that hormone)

• How can you link this to neural transfers, fight or flight, or outward behaviors?

Transmission of incorrect number of chromosomes

• Results in nondisjunctional errors– Occurs when chromosomes don’t

separate correctly during cell division

– Most nondisjunctional fertilizations result in spontaneous abortion (miscarriages)

Chromosomal Abnormalities

1. Eggs can be produced with 21 or 23 autosomes plus X chromosome

2. Eggs can be produced with 22 autosomes without an X or with two X chromosomes

3. Sperms can be produced with 21 or 23 autosomes plus an X or a Y chromosome

4. Sperms can be produced with 22 autosomes without a sex chromosome or with two X, two Y, or both X and Y chromosomes

Autosomal Nondisjunction: Trisomy-21

• Presence of 3 copies of autosome 21, results in expression of Down syndrome

• Typically mentally retarded with a mean IQ of 50 at age 5 and a mean life expectancy of 23 years

– Individuals tend to have round head, flat nasal bridge, protruding tongue, small round ears, spots in the iris of the eye, epicanthic fold in the eyelid, poor muscle tone and coordination

Sex chromosome nondisjunctional conditions

• More common than autosomal ones like Trisomy 21

1. XXX condition• Not a true syndrome, insignificant

percentage express one or more clinical behavioral problems (irregularity in menstruation, retardation, sterility, disturbed personalities)

Sex chromosome nondisjunctional conditions cont’d

2. XYY condition

• Males typically over 6 feet tall

• Acne beyond adolescence– Prison studies in 1960’s show

aggressive/violent behavioral disorders, but they’re not substantiated

Sex chromosome nondisjunctional conditions cont’d

3. Turner syndrome• Females have only one X sex

chromosome (known as XO)• Usually normal intelligence, but evidence

of specific cognitive deficits in math, spatial organization and visual form perception– Where in the brain does Turner syndrome

impact?

Turner Syndrome Females

• Typically short

• Webbed neck

• Lack ovaries and fail to develop secondary sex characteristics

Sex chromosome nondisjunctional conditions cont’d4. Klinefelter syndrome• Males arise from XXY zygote

– Small penis (they’ll have this since birth, but won’t be evident until onset of puberty)

– Secondary sex characteristics will fail to occur (development of chest hair, deepening of voice, further development of testes and penis)

– Breast tissue develops – Fat distribution of females becomes evident– sterility

•Pairs of chromosomes each have a gene for the same trait at the same point on each of the chromosomes

REMEMBER

What happens when recessive genes create abnormal conditions? 1. Tay-Sachs disease

• Defective gene on chromosome 15• When both parents carry the gene, child has

25% chance of developing the disease• 1 in 27 Ashkenazi Jewish population carry the

Tay-Sachs gene

• Progressive loss of nerve function, obvious at 6 months (baby fails to sit up, becomes blind, seizures, paralyzed and dies by age 5)

2. Albinism

• Failure to synthesize or store melanin

• Abnormal nerve pathways to the brain– Twitching of the eyes, inability to perceive

depth or 3D with both eyes

3. Phenylketonuria (PKU)• Severe brain damage and mental retardation

UNLESS the baby is fed special diet low in phenlylanine beginning in infancy and continuing into adulthood

• MR happens because s/he can’t metabolize phenylalinine and amino acid builds up in brain, impairing brain functioning

• Hospitals do routine tests on newborns for this disorder

4. Huntington’s disease

• Degeneration of nervous system

• Forgetfulness, tremors, jerky motions, loss of ability to talk, temper tantrums, blindness, death

• Onset after 30

• Lab tests can identify the gene itself, but not its marker…

Alzheimer’s disease

• A form of Alzheimer’s has been attributed to chromosome 21, but not all cases are associated

Twin Studies

• Refer to articles from first day of school– Dizygotic, monozygotic twins

• Identical twins– Have the same genes, just not

the same number of copy of those genes

– 1 in 3 have separate placentas, thus separate nourishment in utero

• Be familiar with European twin studies and results

Twin Studies

Studying the effects of heredity and environment on two sets of twins -

identical and fraternal

Separated Twins

Separated Twins

Personality, Intelligence

Abilities, Attitudes

Interests, Fears

Brain Waves, Heart Rate

Separated Twins

Critics of separated twin studies note that such similarities can be found between strangers.

Researchers point out that differences between fraternal twins are greater than identical twins.

Conclusions?

Bob

Sach

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Epigenetics

• http://www.pbs.org/wgbh/nova/body/epigenetics.html

• How do identical twins differ if they are human clones? How is this possible?

• What is epigenetic therapy?

• Why is it that identical twins may start to differ during specific periods of life like puberty or pregnancies?

Genetic Relatives vs. Environmental Relatives

• Adoption studies

• Ethics

• Siblings

• Personality vs. attitude

• Can your adopted family help you create who you are, or are you doomed to your genetics?

Biological Versus Adoptive Relatives

Adoption studies, as opposed to twin studies, suggest that adoptees (who may be

biologically unrelated) tend to be different from their adoptive parents and siblings.

Adoptive Studies

Adoptive studies strongly point to the simple fact that biologically related children turn

out to be different 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?

Parenting

Parenting does have an effect on biologically related and unrelated children.

Parenting Influences Children’s

Attitudes, Values

Manners, Beliefs

Faith, Politics

What if I told you…

• We could find a way to live without cancer?• We could find a way to live without war or

conflict?• We could find a way for you to have all the

pleasures and benefits of sex without the possibility of getting pregnant?

• We could find a way to coexist with one another in a peaceful utopia?

• What would you say to that?

Eugenics

• Scientific improving of the human genetic code– super races– Should we study eugenics, at all?

• Benefits? Malevolence?

• Molecular geneticists study the molecular structure and function of genes.– seek to identify specific genes influencing

behavior– Potentially, to prevent problems before they

happen. – risks of labeling people/discrimination.– Prenatal screening poses hopeful

possibilities but also difficult problems as parents become able to select their children’s traits.

• In China and India, where boys are highly valued, testing for an offspring’s sex has enabled selective abortions. Millions of parents will select for health and perhaps for brains and