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.