HGD Chapter 2

Natural Selection is the evolutionary process where those individuals best adapted are most likely to survive & reproduce.

Adaptive behavior is behavior that increases your chances of survival.

Evolutionary perspective emphasizes the importance of adaptation, reproduction & "survival of the fittest" in shaping behavior.

The goal of evolutionary developmental psychology is to use the concepts of evolutionary psychology to understand human development.

Genetic Foundations

A chromosome is a threadlike structure made up of DNA. *in the nucleus of every human cell.

DNA, or deoxyribonucleic acid, contains genetic information.

A gene is a segment of DNA that is in a designated place on the chromosome.

Humans have approximately 20,500 genes.

Each cell has 46 chromosomes arranged in 23 pairs.

The exception is sex cells. Here, we have 23 unpaired chromosomes....

During fertilization, the egg and sperm fuse. The 23 chromosomes from the sperm combine with the 23 chromosomes from the egg.

Mitosis is cellular reproduction; occurs in all cells of the body....

...except in the sex cells. Meiosis causes a second cell division, with half the number of chromosomes.

Fertilization is the fusion of egg & sperm to create a ZYGOTE!

Monozygotic twins (identical twins) come from the spontaneous division of a single zygote.

Dizygotic twins (fraternal twins) are a result of two separate eggs fertilized by two separate sperm, thus creating TWO zygotes.

Susceptibility genes are genes which make us vulnerable to diseases or accelerated aging....

Genotype is a person's genetic heritage; the genetic material.

Phenotype consists of the observable characteristics, including physical & psychological characteristics.

In some cases, one gene always exerts its effects over the other; thus one is dominant and one is recessive.

This is the dominant-and-recessive genes principle.

Sex-linked Inheritance

Since most mutated genes are recessive, those on the X chromosome are only expressed if...

they are in a male.

Chromosomal abnormalities occur when a chromosome does not separate properly.

Some chromosomal disorders:

• Down Syndrome
• Klinefelter Syndrome
• Fragile X Syndrome
• Turner Syndrome
• XYY Syndrome

Down Syndrome

• caused by an extra chromosome 21
• causes intellectual disability
• characterized by certain physical features
• linked to maternal age & paternal age
• 1 in 700 live births

Klinefelter's Syndrome

• males born with an extra X
• causes undeveloped testes
• usually enlarged breasts
• become tall
• 1 in 800 live male births

Fragile X Syndrome

• results from an abnormality in the X
• (typically becomes constricted & breaks)
• lower intelligence, learning disability, attention span
• more frequent in males
•                 (probably x-linked)

Turner Syndrome

• chromosome disorder in females
• either X chromosome is missing or partially deleted
• tend to be shorter & have a webbed neck
• typically infertile, have difficulty in math, but good verbal ability
• occurs 1 in every 2,500 live female births

XYY Syndrome

• male has an extra Y
• may be taller than average
• may have learning or speech difficulties
• may have weaker muscles, delayed puberty, lower testosterone
• 1 in 1,000 live male births

Gene-linked abnormalities occur from defective genes.

Phenylketonuria (PKU)-a genetic disorder where an individual cannot metabolize phenylalanine.

Sickle Cell Anemia-a genetic disorder that impairs functioning of red blood cells.

Occurs most often in African Americans; 1 in 10 is a carrier!

Prenatal Tests

• Ultrasound sonography
• Fetal MRI
• Chorionic villus sampling
• Amniocentesis
• Maternal blood screening

Ultrasound-noninvasive, virtually no risk. Can identify structural abnormalities

Fetal MRI-used to diagnose fetal malformations (usually a followup to ultrasound)

Chorionic Villus Sampling-screens for genetic defects by taking a tissue sample from the placenta.

Amniocentesis- a sample of amniotic fluid is taken by syringe and tested. *small risk of miscarriage

Maternal blood screening-measures substances in the mother's blood that points to birth defects.

Approximately 10-15% of couples in the US experience infertility.

Infertility is the inability to conceive after 12 months of regular intercourse with NO contraception.

Options for infertile couples:

• Surgery
• Hormone-based drugs
• IVF
• adoption...?

Behavior Genetics is the field of study that seeks to discover the influence of heredity and environment on individual differences in human traits and development.

Prenatal Development

Prenatal development lasts approximately 266 days, or 38 weeks.

Three periods of prenatal development:

• Germinal Period (2 wks after conception)
• Embryonic Period (2-8 wks after conception)
• Fetal Period (8 wks after conception til birth)

Germinal Period-rapid cell division and migration.

Embryonic Period-rapid cell differentiation, organogenesis.

Fetal Period-growth and development continues. At 6 months, fetus is viable. Fatty tissue added toward the end of period.

The Brain

Neurogenesis is the production of new neurons.

Neuronal migration- neurons move to their appropriate locations, mature & develop.

Hazards to Prenatal Development

A teratogen is any agent that can potentially cause a birth defect OR negatively alter cognitive & behavioral outcomes.

Psychoactive Drugs

Some examples of Psychoactive drugs:

• Caffeine, Alcohol, Nicotine
• Cocaine, Methamphetamine
• Marijuana
• Heroin

Drugs-Prescription and Nonprescription

Can Include:

• Antibiotics (streptomycin, tetracycline)
• Antidepressants
• Hormones (estrogen, progestin)
• Accutane
• Diet pills, aspirin (higher doses)

Environmental Hazards

Examples:

• radiation
• toxic waste
• environmental pollutants
• X-rays
• heavy metals

Maternal Diseases

Examples:

• Rubella
• Syphilis
• Genital herpes
• HIV/AIDS
• Diabetes

Sensitive periods are times when teratogens are most effective at disrupting prenatal development (especially true during Embryonic Period)

Factors relating to timely prenatal care:

• Culture, race, ethnicity
• Unwanted/unplanned pregnancy
• No prior medical provider
• Lower education, SES
• Lack of insurance

The 3 Stages of Birth

Stage 1: is the longest stage. Begins with contractions, lasts until the baby's head starts to move through the cervix and birth canal. *Avg first birth: 6-12 hours!

Stage 2: lasts until the baby completely emerges. *45 min to 1 hour!

Stage 3: the Afterbirth. The placenta, umbilical cord & other membranes expelled. *Shortest stage, lasting only minutes!

Where do Americans have their babies?

99% in hospitals!!! (this differs in other countries)

A doula is a caregiver who provides physical, emotional and educational support for the mother before, during and after childbirth.

Methods of Childbirth

Using Medications...

3 basic drugs used for labor:
-analgesics (pain relievers)
-anesthetics (pain blockers)
-oxytocin (stimulates contractions)

Other methods:

• Natural childbirth  
• Prepared Childbirth (Lamaze Method)
• Waterbirth
• Acupuncture & Massage
• Cesarean Delivery

APGAR Scale

• assesses the health of baby
• taken at 1 min, then 5 min
• evaluates heart rate, respiratory effort,
• muscle tone, body color & reflex irritability
• score of 0, 1, or 2 in each area

Low Birth Weight & Preterm Infants

Low birth weight babies weigh less than 5 pounds at birth.

Preterm infants are born 3 or more weeks before full term.

Small for date infants have a birth weight below normal for length of pregnancy.

They also have a 400% greater risk of death!

Problems with Low Birth Weight & Preterm Babies:

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• As a group, they have more health problems
• More developmental problems 
• including learning disability, ADHD, asthma
• Also recently associated with autism
• 50% are enrolled in Special Education programs

Kangaroo Care

involves skin to skin contact and the baby lays on the parent's chest.

The Postpartum Period

Physical Adjustments-change in energy level, loss of sleep, dramatic hormone changes, & involution.

Emotional and Psychological Adjustments- postpartum fluctuations are common.

Postpartum Depression vs. "the Blues"

Postpartum blues affects 70% of mothers. Lasts 1-2 weeks; subsides on its own.

Postpartum Depression symptoms linger for weeks or months and interfere with functioning. 10% of mothers affected.

Bonding- special bond between newborns and their caregivers.