Nature & Nurture, evolutionary psychology, & the prenatal environment

Dr. Carolyn R. Fallahi

Nature-Nurture

Which is more important?The Diathesis stress modelThe Liability/threshold modelWe figure out the relative amount of nature

(genetics, biology, chemistry) & nurture (environment).

What about psychiatric disorders?

Study Techniques

Twin Research Identical versus fraternal twins (monozygotic

versus dizygotic)Shared environmental experiences

Common experiences, e.g. parent’s personality, intelligence, SES status, neighborhood live in, parenting techniques

Nonshared environmental experiences Child’s own experiences within and outside the

family that are not shared with siblings

Epigenetic View

The interaction of heredity and environment. Heredity directs the kind of environmental

experiences a person has. There is ongoing bidirectional interchange. For example, the development of hearing and

eyesight.

The study of Feral Children

Wild children who have been separated from society.

The Case of Genie. Other cases.

Evolutionary Psychology

Species HeredityAll most everyone has 2 eyesWe all develop in similar ways at similar ages.

Evolutionary Theory

Charles Darwin (1809-1882). Theory of evolution: sought to explain

how the characteristics of a species change over time and how new species can evolve from earlier ones.

Behavioral Genetic Studies

Intelligence: overall heritability of IQ scores is about .50 or 50% of the variance is explained.

Identical twins raised together: .86 Raised apart: .72 Fraternal twins: .60 & .52 Biological siblings: .47 & .24 Biological parent & child: .42 & .22 Adopted parent & adopted child: .19

Temperament & Personality

Temperament: a set of tendencies to respond in predictable ways.

Buss & Plomin (1984) found .50 to .60 average correlations between temperatment scores of identical twins. The correlations for fraternal twins are about 0.

Psychological Disorders

Schizophrenia: disturbances in logical thinking, emotional expression, social behavior.

Originally: thought due to a cold and inconsistent mother.

Now: concordance rates for identical twins: 48%; fraternal twins 17%.

1% of the general population has Schizophrenia.

Teratogens

Can someone’s emotional experiences cause problems for the baby?….Anxiety in mom may affect sleeping patterns

of the fetus prior to birth.

Mom & Dad’s Behavior

Mom & dad’s behavior both before & after conception can produce lifelong consequences for the child.

We are used to thinking it’s only mom. Some consequences show up immediately, but

half the possible problems aren’t apparent before birth.

Others may not appear until years after birth.

Teratogenic agents

Teratogens are environmental agents such as:DrugChemicalVirusOther factors that produce a birth defect.

The role of the placenta

The job of the placenta is to keep teratogens from reaching the fetus.

The timing & quality of a teratogen At some periods: the same teratogen can

have only a minimal impact. At other periods … profound

consequences. Different organ systems are vulnerable to

teratogens at different times during development.

Teratogens

What makes a teratogen problematic? Critical period Dosage and duration Genetic makeup environment

Mother’s Diet

Mother’s diet clearly plays a role in bolstering the development of the fetus.

Mother eats a varied diet high in nutrients is apt to have fewer complications during pregnancy, an easier labor, and a generally healthier baby.

The problem of diet

The World Food Council has estimated that there were 550 million hungry people in the world.

Mother’s Age

Women who give birth when over the age of 30 are at greater risk for a variety of pregnancy and birth complications than younger ones.

They are more apt to give birth prematurely.

Their children are more likely to have low birth weights.

Mother’s Age

Older mothers are more likely to give birth to children with Down Syndrome, a form of mental retardation.

About 10% babies born to mothers over 40 has Down Syndrome.

For mothers over 50, the incidence increases to 25% or one in four.

Younger Mothers

Women who become pregnant during adolescence (20% of all pregnancies) - are more likely to have premature deliveries.

The mortality rate of infants born to adolescent mothers is double that for mothers in their 20s.

Mother Illness

An illness in a pregnant woman can have devastating consequences.

For example, the onset of rubella (German measles) in the mother prior to the 11th week of pregnancy is likely to cause serious consequences in the baby: blindness, deafness, heart defects, or brain damage.

In later stages of a baby, however, adverse consequences in the pregnancy become increasingly less likely.

Mother Illness

Another example: Chicken pox. This may produce birth defects while mumps may increase the risk of miscarriage.

Sexually transmitted diseases, e.g. syphilis, can be transmitted directly to the fetus, which will be born suffering from the disease.

Mother Illness

Gonorrhea: can be passed through the birth canal at birth.

AIDS: Mothes who have AIDS or carriers of the virus may pass it on to their fetuses through the blood that reaches the placenta.

Mother’s Drug Use

Mother’s use of many kinds of drugs, both legal and illegal, pose serious risks to the unborn child.

Aspirin Thalidomide

Illicit Drugs

Issues: the purity of the drugs purchased illegally varies significantly, so drug users can never be quite sure what specifically they are ingesting.

The effects of some commonly used illicit drugs can be particularly devastating.

Issues

Marijuana

Can restrict oxygen that reaches the fetus. Can lead to an infant who is irritable,

nervous, and easily disturbed. Cancer

Cocaine

“Crack babies” - cocaine produces an intense restriction of the arteries leading to the fetus, causing a significant reduction in the flow of blood and oxygen.

This process increases the risk of fetal death.

Mother’s use of alcohol/tobacco

Increasing evidence suggests that even small amounts of alcohol and nicotine can disrupt the development of the fetus.

Alcohol: 1/750 born with fetal alcohol syndrome (FAS): below-average intelligence & sometimes mental retardation, delayed growth, facial deformities.

Mother’s use of alcohol/tobacco

Even mothers who use smaller amounts of alcohol = fetal alcohol effects (FAE).

Just 2 drinks/day.

Smoking

Reduces the oxygen and increases the carbon monoxide of the mother’s blood.

Fathers

Fathers affect the prenatal environment. Fathers-to-be should avoid smoking. Also, a father’s use of alcohol and illegal

drugs such as cocaine not only may lead to chromosomal damage.

Fathers

Father’s age: Risk of miscarriage increases as the father’s age increases.

There is also an increased risk of neural tube defects, kidney problems, and Down Syndrome.

Increased risk of congenital heart defects. Environmental toxins.