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Human Development

Human Development. Biological Beginnings. The Evolutionary Perspective. Charles Darwin: The Origin of Species Natural selection : genes which have survival value will be more abundant in the next generation Survival of the fittest ; individuals who survive are better adapted

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Human Development

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  1. Human Development Biological Beginnings

  2. The Evolutionary Perspective • Charles Darwin: The Origin of Species • Natural selection: genes which have survival value will be more abundant in the next generation • Survival of the fittest; individuals who survive are better adapted • Those who survive reproduce and pass on their characteristics to the next generation

  3. The Evolutionary Perspective • Evolutionary psychology: emphasizes adaptation, reproduction, and survival of the fittest in shaping behavior • Using evolutionary principles to explain human behavior

  4. Evolutionary Psychology • Argument: evolution shapes decision making, aggression, fears, mating/sexual behavior • “gene centered” perspective • “epigentic” perspective • Critique: deterministic; downplays the role of culture and the environment

  5. Chromosomes • We start as a single cell, consisting of our entire genetic code • Chromosomes: located in the nucleus; threadlike structures that carry our genes • We have 46 chromosomes or 23 pairs • 23 from mother, 23 from father • The 23rd pair determines our sex

  6. Genes and DNA • Genes: unit of hereditary information, composed of DNA; each gene has its own function and location • DNA: contains genetic information and instructions

  7. 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 Fig. 2.3

  8. Polygenetic Inheritance • Polygenetic Inheritance: when many genes interact to influence a characteristic • Few behavioral traits are due to just one gene

  9. Genes • Human Genome Project: • Humans have 20,000-25,000 genes • All humans: genes are 99% the same • Humans and apes share 96-98% of their genes

  10. Nature vs. Nurture • Nature: the role of genes • Nurture: the role of the environment and external conditions **Interactionist Perspective/Epigenetic View: Both nature and nurture are important to development

  11. Childhood Aggression:The Role of Nurture(Garbarino, 2005) • RISK FACTORS: • PROTECTIVE FACTORS: • Poverty • Abuse • Parental abandonment • Large family size • Parental addiction • Experiencing racism • Low educational attainment • Spiritual emptiness • Positive adult role models • Intellectual achievement • Reading for pleasure • Playing an instrument • Positive communication with parents • Spirituality • Believing we control our fate

  12. Childhood Aggression: The Role of Nature • Nature: • Genetic Predisposition: • Abnormal MAOA gene

  13. How Nature and Nurture Work Together • Will a genetic predisposition for a certain behavioral trait lead to the expression of that trait? • Answer: it depends.

  14. How Nature and Nurture Work Together • Environmental influences (nurture) determine whether or not the gene is turned “on” • ***Genes are NOT destiny

  15. Epigenetic/Interactionist Perspective • Development is the result of an ongoing, bidirectional interchange between heredity and environment

  16. Behavioral Genetics • A field that looks at the influence of heredity and environment • Twin studies: comparing identical and fraternal twins • Adoption studies: are children more similar to the biological or adoptive parent?

  17. Behavioral Genetics:Limitations of Twin Studies • Shared: the environments siblings have in common (i.e. the household) • Non-Shared: influences outside the house; peer groups, differential parental treatment, events experienced at school, etc. • The role of environments

  18. Behavioral Genetics:Limitations of Adoption Studies • Similarities between adoptive and biological parents • Children may be placed in similar families

  19. Niche-picking • Niche-picking: when children seeks out the environments they find appealing; driven by their genes • Example: a child may inherit a trait like extraversion; he/she will seek out highly social environments.

  20. Genetic Disorders • Down syndrome: • Extra copy of chromosome 21 • Very young mother or mothers over age 38 at greater risk

  21. KlinefelterSyndrome Males have an extra X chromosome Fragile X syndrome Abnormality in the X chromosome Turner syndrome Females missing an X chromosome XYY syndrome Males have an extra Y chromosome Sex-Linked Chromosome Abnormalities

  22. The Course of Prenatal Development • Germinal period: 2 weeks after conception; zygote is created, attaches to the uterine wall • Embryonic period: 2 to 8 weeks after conception • Cell layers start to form organs • Umbilical cord connects to placenta • Fetal period • From 2 months after conception to birth • Trimesters of pregnancy

  23. Prenatal Diagnostic Testing • Amniocentesis: samples amniotic fluid; to check for chromosomal or metabolic disorders • Genetic Counseling: to understand a child’s risk for inheriting a genetic disorders

  24. Teratogens • Teratogen: agents that cause birth defects • Severity of damage affected by: • Dose • Genetic susceptibility • Time of exposure

  25. Teratogens • Heavy drinking: fetal alcohol syndrome (FAS) Facial deformities, low birth weight, respiratory problems • Nicotine: preterm births, low birth weight, respiratory problems, increased risk of SIDS • Cocaine: reduced birth weight, length, and head circumference • Heroin: behavioral problems, tremors, disturbed sleep, excessive crying, irritability • Methamphetamine: low birth weight, developmental and behavior problems

  26. Environmental hazards: Lead Radiation Pesticides Carbon minoxide Mercury PCBs Infectious diseases AIDS STDs Teratogens

  27. Other Parental Factors • Nutrition • Children born to malnourished mothers are more likely to be malnourished/low birth weight • Maternal Age • Children born to adolescent mothers: often premature, mortality rate is twice that of mothers in their twenties • Mothers over 35: higher risk of infants with low birth weight or Down Syndrome

  28. Other Parental Factors • Emotional States/Stress: Physiological changes affecting a mother during times of stress are transmitted to the fetus • Mothers under stress are 4x’s more likely to deliver early • Stress puts mothers at risk for unhealthy behaviors • Irregular contractions/difficult labor

  29. Low birth weight Low brain weight and risk of brain injury Lung and liver disease ADHD and learning problems/disabilities Breathing problems and asthma Lower achievement levels Some effects can be reversed

  30. Apgar Scale • A scale used to assess the health of a newborn 1-5 minutes after birth • Measures heart rate, respiratory effort, muscle tone, body color, reflexes (2pts per category) • Total score: 7-10 indicates good condition; 5 indicates possible developmental difficulties; 3 or below signals an emergency

  31. The Apgar Scale Fig. 2.14

  32. Bonding • Needs to occur shortly after birth • Early emotional attachments may create healthy interactions after leaving hospital • Massages and tactile stimulation for premature infants affect development • Research indicates that massage is particularly helpful for low birth weight infants

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