Nature & Nurture, evolutionary psychology, & the prenatal environment

Nature & Nurture, evolutionary psychology, & the prenatal environment Dr. Carolyn R. Fallahi

Nature-Nurture • Which is more important? • The Diathesis stress model • The Liability/threshold model • We 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 Heredity • All most everyone has 2 eyes • We 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: • Drug • Chemical • Virus • Other 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.

Nature & Nurture, evolutionary psychology, & the prenatal environment