Biological Beginnings

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The Evolutionary Perspective Genetic Foundations of Development Heredity and Environment interaction:

The Nature-Nurture Debate

Prenatal Development Birth

The Evolutionary Perspective

Natural selection and adaptive behaviorDarwin and his observationsAll organisms must adapt in life

Evolutionary psychologyEmphasizes adaptation, reproduction,

and survival of the fittest in shaping behaviorEvolution explains human physical features

and behaviors

The Evolutionary Perspective Natural selection and adaptive behavior

Darwin and his observationsAll organisms must adapt in life

Evolutionary psychologyEmphasizes adaptation, reproduction,

and survival of the fittest in shaping behaviorEvolution explains human physical features and

behaviors

Evolutionary Developmental Psychology

Explaining humans and their behaviorLarger brains and more complex societiesTakes longest of all mammals to matureSome evolved mechanisms of adaptation not

compatible with modern society

Evolution and Life-Span Development

Benefits of evolutionary selection decrease with age Natural selection failures: harmful conditions and non-

adaptivecharacteristics As adults weaken biologically, culture-based needs increase Alternative: ‘bi-directional view’

Baltes’ view of evolution and culture across the life span

Evaluating Evolutionary Psychology

Remains just one theoretical approach.

Evolution does not dictate behavior.

Biology allows broad range of cultural possibilities.

Genetic Foundations of Development

DNA and the collaborative gene

DNA — deoxyribonucleic acid

Chromosomes — thread-like structures

Genes — units of hereditary information

Human Genome Project

30,000 genes in humans

Genetic Foundations

Cells, Chromosomes, Genes, and DNAGenetic Foundations

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

The Collaborative Gene 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

Genetic Foundations

The Collaborative Gene Genes and chromosomes

Identical and fraternal twins Mutated gene Genotype — all of one’s genetic makeup Phenotype — observable characteristics

Genetic Foundations

Genetic Principles Dominant and recessive genes

Sex-linked genesX-linked inheritance for males and females

Genetic imprintingImprinted gene dominates

Poly-genetically determined characteristicsMany genes interact to influence a trait

Genetic Foundations

b bB bB bB B

Blond hair

Brown hairHow brown-

haired parents can have a

blond-haired child: the gene for blond hair is

recessive MotherB b

FatherB b

Genetic Foundations

Genetic PrinciplesChromosome abnormalities

Down syndrome

Sex-linked chromosome abnormalities Klinefelter syndrome

Fragile X syndrome

Turner syndrome

XYY syndrome

Sex-Linked Chromosome Abnormalities

Genetic Foundations

KlinefelterSyndrome

Fragile X syndrome

Turner syndrome

Males have an extra X chromosome

Abnormality in the X chromosome

Females missing an X chromosome

XYY syndrome Males have an extra Y chromosome

Genetic Foundations

Gene-Linked Abnormalities PKU: phenylketonuria Sickle-cell anemia Cystic fibrosis Diabetes Hemophilia Genetic disorders can sometimes be compensated

for by other genes or events

Nature-Nurture Debate Behavior Genetics

Studies influence of heredity and environment on individual differences

Studies use twins or adopteesMonozygotic and dizygotic twinsAdoption study: examine behavior and

psychological characteristics

Heredity, Environment, and Individual Differences

Heredity-Environment Correlations

In infancy, environment mostly controlled by parents

As children age, their experiences extend more beyond the family’s influence

Shared environments are analyzedCommonalities between children attributed to heredity-

environment interaction

Passive genotype-environment correlations Evocative genotype-environment correlations Active (niche-picking) genotype-environment

correlations

In infancy, environment mostly controlled by parents

As children age, their experiences extend more beyond the family’s influence

Shared environments are analyzedCommonalities between children attributed to

heredity-environment interaction

The Heredity-Environment and Epigenetic Views

The Course of Prenatal Development

Germinal period: 2 weeks after conception Embryonic period: 2 to 8 weeks after conception

Three layers: endodem, mesoderm, ectodermUmbilical cord connect to placentaOrganogenesis

Fetal periodFrom 2 months after conception to birthTrimesters of pregnancy

Prenatal Development

Second trimester

Third trimester

First trimester

0 - 4 weeks

Less than 1 inch long

12 weeks

32 weeks

8 weeks

Less than 1/10th of inch long

16½ -18 inches, wt: 4-5 lbs

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

36-38 weeks

28 weeks

19 inches, wt: 6 lbs

14-17 inches, wt: 2½ -3 lbs

The three trimesters of prenatal development

Prenatal Diagnostic Tests Ultrasound sonography Chorionic villi sampling: small sample of placenta taken Amniocentesis: samples amniotic fluid Maternal blood test

The BrainNeurons – 100 billionBirth defects and neural tubeNeuronal migration occurs

Hazards to Prenatal Development Teratogen: agent causing birth defects

Severity of damage affected byDose Genetic susceptibilityTime of exposure

Effects of prescription and nonprescription drugs

Teratogens and Timing of Their Effects on Prenatal Development

Hazards to Prenatal Development

Psychoactive drugsCaffeineAlcohol and fetal alcohol syndrome (FAS)Nicotine’s link to SIDS, ADHD, low birth weightEffect of father’s smokingCocaine, marijuana, and heroinMethamphetamine

Environmental hazards and pollutants

Hazards to Prenatal Development

Incompatible blood types of parentsRh-positive and Rh-negativeMaternal diseases like German measles, syphilis, HIV

and AIDS Other prenatal factors

Nutrition, prenatal education and careMaternal age and risksMaternal emotional states and stressPaternal factorsEnvironmental factors

Prenatal Care Prenatal programs

EducationMedical careSocial and nutritional servicesLow birth weight and infant mortality ratesView of pregancy vary among cultures

and ethnic groups

The Birth Process Stages of birth: occurs in three stages

Uterine contractionsBaby’s head moves through birth canalAfterbirth when placenta, umbilical cord,

and other membranes are detached and expelled

Baby must withstand stress of birth

Strategies for Childbirth Deciding what setting, who attends, and what technique will

be used Home delivery, birthing center, or hospital? 99% of all U.S. births occur in hospitals Home births more common outside U.S.

Doula as caregiver Role of midwife, nurse, and physician

Methods of Delivery Medication with analgesics (epidural block, oxytocics, etc.) Possible effects of drugs on fetus Natural childbirth Prepared childbirth and the Lamaze method Cesarean sections for breech babies,

other risks and benefits

Methods of DeliveryNonmedicated techniques

Waterbirth more in European countriesMassage reduces pain and anxietyAcupuncture is standard in ChinaHypnosis has some positive effectsMusic therapy reduces stress, manages pain

Assessing the NewbornApgar Scale: heart, reflexes, and color

Brazelton Neonatal Behavioral Assessment Scale (BNBAS)A sensitive index of neurological competenceFour categories in global terms

Neonatal Intensive Care Unit Network Neurobehavioral Scale (NNNS)Analysis of behavior, neurological and stress

responses, and regulatory capacities

The Apgar Scale

Low Birth Weight and PretermLow birth weight infants in U.S. and world

Weigh less than 5.5 lbsVery low birth weight: less than 3 lbsPreterm infants: 35 or fewer weeks after

conception (about 12% of U.S. births)Small-for-date infants: weigh less than they

shouldEthnic variations characterize preterm birth

Causes and consequences

Low Birth Weight and PretermLow birth weight infants in U.S. and world

Weigh less than 5.5 lbsVery low birth weight: less than 3 lbsPreterm infants: 35 or fewer weeks after

conception (about 12% of U.S. births)Small-for-date infants: weigh less than they

shouldEthnic variations characterize preterm birth

Causes and consequences

Kangaroo Care and Massage Therapy

Kangaroo careHolds infant to promote skin-to-skin contact

between infant and caregiverCan promote

• Better breathing• Longer sleep periods• Weight gain• Less crying• Longer periods of alertness

Tiffany Field’s Research on Massage Therapy

Massage therapy led to 47% greater weight gain for preterm infants

Also demonstrated benefits of massage for Labor pain Asthma ADHD Arthritis Autistic children

Weight Gain Comparison of

Premature Infants Who

Were Massaged and Not

Massaged

BondingNeeds 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

Biological Beginnings

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