A Topical Approach to LIFE-SPAN DEVELOPMENT

1. A Topical Approach toLIFE-SPAN DEVELOPMENT Chapter Two: Biological Beginnings John W. Santrock

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

3. The Evolutionary Perspective • Evolutionary psychology • Emphasizes adaptation, reproduction, and survival of the fittest in shaping behavior • Evolution explains human physical features and behaviors

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

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

6. Baltes’ View of Evolution and Culture Across the Life Span Fig. 2.2

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

8. Nucleus (center of cell) contains chromosomes and genes Gene: a segment of DNA (spiraled double chain) containing the hereditary code Chromosomes are threadlike structures composed of DNA molecules Cells, Chromosomes, Genes, and DNA Fig. 2.3

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

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

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

12. How brown-haired parents can have a blond-haired child: the gene for blond hair is recessive Brown hair B Blond hair b Father B b Mother B b B B B b B b b b

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

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, Tay-sachs and Huntington diseases • Can sometimes be compensated for by other genes or events

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

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

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

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

19. The Heredity-Environment and Epigenetic Views Fig. 2.9

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

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

22. The Three Trimesters of Prenatal Development Fig. 2.10

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

24. Hazards to Prenatal Development • Teratogens • Agents causing birth defects • Severity of damage affected by • Dose • Genetic susceptibility • Time of exposure • Prescription, nonprescription drugs

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

26. Teratogens and Timing of Their Effects on Prenatal Development Fig. 2.12

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)

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

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

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

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

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

33. The Apgar Scale Fig. 2.14

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

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

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

37. 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

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

39. The End