1. Slide 1 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 1 A Topical Approach to LIFE-SPAN DEVELOPMENT John W. Santrock Chapter Two: Biological Beginnings

2. Slide 2 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 3 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 4 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 5 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 6 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 6 Fig. 2.2 Baltes’ View of Evolution and Culture Across the Life Span

7. Slide 7 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 8 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 8 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

9. Slide 9 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 10 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 11 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 12 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 12 b B b B b B Blond hair Brown hair How brown- haired parents can have a blond-haired child: the gene for blond hair is recessive Mother B b Father B b

13. Slide 13 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 14 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 15 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 16 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 17 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 18 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 19 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 19 The Heredity-Environment and Epigenetic Views Fig. 2.9

20. Slide 20 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 21 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 22 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 22 The Three Trimesters of Prenatal Development First trimester 0-4 weeksLess than 1/10th of inch long 8 weeksLess than 1 inch long 12 weeks3 inches long, wt: 1 ounce Second trimester 16 weeks5.5 inches long, wt: 4 ounces 20 weeks10-12 inches, wt: ½ -1 lbs 24 weeks11-14 inches, wt: 1-1½ lbs Third trimester 28 weeks14-17 inches, wt: 2½ -3 lbs 32 weeks16½ -18 inches, wt: 4-5 lbs 36-38 weeks19 inches, wt: 6 lbs Fig. 2.10

23. Slide 23 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 24 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 25 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 26 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 26 Fig. 2.12 Teratogens and Timing of Their Effects on Prenatal Development

27. Slide 27 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 28 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 29 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 30 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 31 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 32 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 33 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 33 Fig. 2.14 The Apgar Scale

34. Slide 34 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 35 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 36 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 37 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 38 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 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. Slide 39 © 2010 The McGraw-Hill Companies, Inc. All rights reserved. 39 The End