dev psych.ch2.keynote
TRANSCRIPT
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A Topical Approach to LIFE-SPAN DEVELOPMENT
John W. Santrock
Chapter Two:
Biological Beginnings
Slide 2
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The Evolutionary Perspective
• Natural selection – Evolutionary process where the best adapted
individuals in a species survive and reproduce
• Natural selection and adaptive behavior– Darwin: On the Origin of Species (1859)– All organisms must adapt in life
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The Evolutionary Perspective
• Evolutionary psychology– Emphasizes adaptation, reproduction, and survival
of the fittest in shaping behavior– Evolution explains human physical features and
behaviors
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The Evolutionary Perspective
• Evolutionary developmental psychology– Explaining humans and their behavior
• Larger brains and more complex societies• Takes longest of all mammals to mature• Some evolved mechanisms of adaptation not compatible
with modern society
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The Evolutionary Perspective
• Evolution and life-span development– Natural selection
• Benefits decrease with age• Failures: harmful conditions and non-adaptive
characteristics• As adults weaken biologically, culture-based needs
increase• Alternative: bi-directional view
Slide 6
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6Fig. 2.2
Baltes’ View of Evolution and Culture Across the Life Span
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Genetic Foundations of Development
• The collaborative gene– Nucleus of a human cell:
• Chromosomes — thread-like structures • DNA — double helix-shaped molecule• Genes — units of hereditary information
• Human Genome Project– 20,500 genes in humans– Genetic expression and inherited traits
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Cells, Chromosomes, Genes, and DNA
Fig. 2.3
Nucleus (center of cell) contains
chromosomes and genes Chromosomes are
threadlike structures composed of DNA
molecules
Gene: a segment of DNA (spiraled double chain)
containing the hereditary code
Slide 9
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Genetic Foundations of Development
• Genes and chromosomes– Mitosis — cell nucleus duplicates– Meiosis — cell division forms gametes– Fertilization — egg and sperm form zygote– Genetic variability in the population– X and Y chromosomes determine sex
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Genetic Foundations of Development
• Genes and chromosomes– Sources of variability
• Each zygote is unique– Identical and fraternal twins– Muted genes due to environmental agent– Genotype: all of one’s genetic makeup– Phenotype: observable characteristics
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Genetic Foundations of Development
• Genetic principles– Dominant and recessive genes
• Sex-linked genes– X-linked inheritance for males and female
• Genetic imprinting– Imprinted gene dominates
• Poly-genetically determined characteristics– Many genes interact to influence a trait
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b bB bB bB B
b
B
Blond hair
Brown hair
How brown-haired parents
can have a blond-haired
child: the gene for blond hair is
recessiveMother
B bFather
B b
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Genetic Foundations of Development
• Chromosomal and gene-linked abnormalities– Down syndrome: 2 copies of chromosome 21– Sex-linked abnormalities
• Klinefelter syndrome: XXY instead of XY• Fragile X syndrome: X in boys is fragile, breaks• Turner syndrome: girl is XO instead of XX• XYY syndrome: link to criminal males unproven
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Genetic Foundations of Development
• Chromosomal and gene-linked abnormalities– Gene-linked abnormalities
• Phenylketonuria (PKU) – treated by diet• Sickle-cell anemia – red blood cells affected• Cystic fibrosis, diabetes, hemophilia, spina bifida, Tay-
sachs and Huntington diseases • Can sometimes be compensated for by other genes or
events
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Heredity and Environment Interaction:The Nature-Nurture Debate
• Behavior genetics – Studies genetic impact on traits and development– Tests for genetic/environmental influences
• Twin studies– Shared and nonshared factors
• Adoption studies– Effects of biological and adoptive parents
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Heredity and Environment Interaction:The Nature-Nurture Debate
• Heredity-environment correlations– Passive genotype-environment
• Parents provide/guide child’s interests
– Evocative genotype-environment • Some traits elicit more adult responses
– Active (niche-picking) genotype-environment• Child seeks/selects favorable environments
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Heredity and Environment Interaction:The Nature-Nurture Debate
• Heredity-environment correlations– Heredity directs environmental experiences– In infancy, environment mostly parent-controlled– As child ages, experiences extend beyond family– Some environments can mute or strengthen
genetic traits– Critics: heredity gets too much credit
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Heredity and Environment Interaction:The Nature-Nurture Debate
• Epigenetic view– Development is ongoing– Bi-directional interchange of heredity/environment– Infancy
• Positive and negative environmental experiences can modify genetic activity
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The Heredity-Environment and Epigenetic Views
Fig. 2.9
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Prenatal Development
• Course of prenatal development– Germinal period: creation of fertilized egg– Embryonic period: cell differentiation of embryo
• Endoderm – digestive/respiratory systems• Ectoderm – nervous system, sensory receptors• Mesoderm – circulatory, bones, muscles, excretory and
reproductive systems• Organagenesis: organ formation
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Prenatal Development
• Course of prenatal development– Fetal period: lasts for 7 months, 3 trimesters– Brain:
• 100 billion neurons (nerve cells)• Neural tube formed from ectoderm
– Birth defects can cause death, retardation• Neurogenesis – new cells formed • Neuronal migration – cell specialization
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The Three Trimesters of Prenatal Development
First trimester
0-4 weeks Less than 1/10th of inch long
8 weeks Less than 1 inch long
12 weeks 3 inches long, wt: 1 ounce
Second trimester
16 weeks 5.5 inches long, wt: 4 ounces
20 weeks 10-12 inches, wt: ½ -1 lbs
24 weeks 11-14 inches, wt: 1-1½ lbs
Third trimester
28 weeks 14-17 inches, wt: 2½ -3 lbs
32 weeks 16½ -18 inches, wt: 4-5 lbs
36-38 weeks 19 inches, wt: 6 lbsFig. 2.10
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Prenatal Diagnostic Tests
• Tests for abnormality– Ultrasound sonography– Fetal MRI: better than ultrasound – Chorionic villus sampling: samples placenta– Amniocentesis: samples amniotic fluid
– Maternal blood screening (triple screen test)
– Noninvasive prenatal diagnosis (NIPD): tests fetal cells (DNA) in mother’s blood
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Hazards to Prenatal Development
• Teratogens– Agents causing birth defects– Severity of damage affected by
• Dose• Genetic susceptibility• Time of exposure
– Prescription, nonprescription drugs
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Hazards to Prenatal Development
• Teratogens– Psychoactive drugs
• Caffeine, cocaine, methamphetamines, marijuana, and heroin
• Alcohol and fetal alcohol syndrome (FAS) • Nicotine’s link to SIDS, ADHD, low birth weight
– Paternal smoking during pregnancy
Slide 26
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26Fig. 2.12
Teratogens and Timing of Their Effects on Prenatal Development
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Hazards to Prenatal Development
• Other prenatal factors– Incompatible blood types (Rh factor)– Maternal diseases
• STDs, HIV and AIDS; Rubella measles
– Diet and nutrition (vitamins, folic acid); weight• Toxins in foods, mercury in fish
– Maternal age, emotional states, and stress– Environmental hazards (toxins, waste)
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Prenatal Care
• Prenatal care varies around the world– Quality of medical care visits, education– Low-birth weight and infant mortality rates– Outside the United States: free/low cost prenatal
care, liberal maternity leave– Impact of cultural/ethnic beliefs about pregnancy
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Birth
• Birth process– Stages of birth
• Labor occurs in three stages: – Uterine contractions – Baby’s head begins to enter birth canal– Afterbirth (shortest stage)
– Birth attendants vary across cultures• Midwifery• Doula
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Birth
• Methods of childbirth– Natural childbirth: reduce maternal pain through
education (breathing, relaxation techniques)– Prepared childbirth: Lamaze method– Nonmedicated techniques to reduce pain
• Waterbirth• Massage, acupuncture, hypnosis• Music therapy
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Birth
• Methods of childbirth– Cesarean delivery (surgical procedure)
• Breech position birth• Benefits and risks continue being debated
• From fetus to newborn– Vernix caseosa (protective skin grease at birth)– Baby must withstand stress of birth
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Birth
• Assessing the newborn– Apgar Scale: heart, reflexes, and color– Brazelton Neonatal Behavioral Assessment
Scale (BNBAS)• A sensitive index of neurological competence
– Neonatal Intensive Care Unit Network Neurobehavioral Scale (NNNS)
• Analysis of behavior, neurological and stress responses, and regulatory capacities
Slide 33
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33Fig. 2.14
The Apgar Scale
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Birth
• Low birth weight and preterm infants– Low birth weight: less than 5 ½ lbs at birth
• Very low: less than 3 lbs at birth• Extremely low: under 2 lbs at birth
– Preterm: born in 35 weeks or less after conception– Small for date (small for gestational age infants)
• Birth weight below normal for gestational age
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Birth
• Low birth weight – Incidences
• Not all preterm babies are low birth weight• High rates in developing countries from poverty• Rates increasing in the United States in last two decades• Lowest rates in Nordic countries
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Birth
• Low birth weight– Causes
• Poor maternal health and nutrition– Maternal diseases and infections
• Cigarette smoking is leading cause• Weekly hormone injections can lower rates
– Consequences• Learning difficulties, more behavioral problems
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Birth
• Nurturing preterm infants– Intensive enrichment (medical, educational)– Neonatal Intensive Care Unit (NICU) interventions
• Kangaroo care: skin-to-skin contact– Stabilizes bodily functions (ie: breathing) – Better sleep, weight gain, more alertness
• Massage therapy
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Birth
• Bonding – Special part of parent-infant relationship– Needs to occur shortly after birth– Early emotional attachments may create healthy
interactions after leaving hospital– Rooming-in arrangements offered– Massages and tactile stimulation for premature
infants affect development
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The End