Download LIFE-SPAN DEVELOPMENT

Slide 1
A Topical Approach to
LIFE-SPAN DEVELOPMENT
Chapter Two:
Biological Beginnings
John W. Santrock
© 2010 The McGraw-Hill Companies, Inc. All rights reserved.
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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
© 2010 The McGraw-Hill Companies, Inc. All rights reserved.
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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
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Baltes’ View of Evolution and Culture
Across the Life Span
Fig. 2.2
Slide 6
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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
Nucleus (center of
cell) contains
chromosomes and
genes
Fig. 2.3
Chromosomes are
threadlike structures
composed of DNA
molecules
Gene: a segment of DNA
(spiraled double chain)
containing the hereditary
code
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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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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
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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, Taysachs 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
© 2010 The McGraw-Hill Companies, Inc. All rights reserved. 16
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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
0-4 weeks
First
trimester
Second
trimester
Third
trimester
Fig. 2.10
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
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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
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Teratogens and Timing of Their Effects on
Prenatal Development
Fig. 2.12
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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
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The Apgar Scale
Fig. 2.14
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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
© 2010 The McGraw-Hill Companies, Inc. All rights reserved. 37
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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
© 2010 The McGraw-Hill Companies, Inc. All rights reserved. 38
Slide 39
The End
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