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Slide 1 A Topical Approach to Life-Span Development 6e Chapter Two: Biological Beginnings John W. Santrock © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 2 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 3 The Evolutionary Perspective • Evolutionary psychology – Emphasizes adaptation, reproduction, and survival of the fittest in shaping behavior – Evolution explains human physical features and behaviors © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 4 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 5 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 6 Figure 2.2 - Baltes’ View of Evolution and Culture Across the Life Span © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 7 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 8 Figure 2.3 - Cells, Chromosomes, Genes, and DNA 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 9 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 10 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 11 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 12 How brownhaired parents can have a blond-haired child: the gene for blond hair is recessive B Brown hair Blond b hair Father Bb B B Mother Bb B b B b b b © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 13 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 14 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, Taysachs and Huntington diseases • Can sometimes be compensated for by other genes or events © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 15 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 16 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 17 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 18 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 19 Figure 2.9 - The Heredity-Environment and Epigenetic Views © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 20 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 21 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 22 Figure 2.10 - The Three Trimesters of Prenatal Development 0-4 weeks First trimester Second trimester Third trimester Less than 1/10th of inch long 8 weeks Less than 1 inch long 12 weeks 3 inches long, wt: 1 ounce 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 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 lbs © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 23 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 24 Hazards to Prenatal Development • Teratogens – Agents causing birth defects – Severity of damage affected by • Dose • Genetic susceptibility • Time of exposure – Prescription, nonprescription drugs © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 25 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 26 Figure 2.12 - Teratogens and Timing of Their Effects on Prenatal Development © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 27 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) © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 28 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 29 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 30 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 31 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 32 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 33 Figure 2.14 - The Apgar Scale © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 34 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 35 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 36 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 37 Birth • Nurturing preterm infants – Intensive enrichment (medical, educational) – Neonatal Intensive Care Unit (NICU) interventions • Kangaroo care: skin-to-skin contact – Stabilizes bodily functions (i.e. breathing) – Better sleep, weight gain, more alertness • Massage therapy © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 38 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 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Slide 39 The End © 2012 The McGraw-Hill Companies, Inc. All rights reserved.