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John W. Santrock

Children. 2. Biological Beginnings. John W. Santrock. Biological Beginnings. What Is the Evolutionary Perspective? What Are the Genetic Foundations of Development? What Are Some Reproductive Challenges and Choices? How Do Heredity and Environment Interact? The Nature-Nurture Debate.

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John W. Santrock

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  1. Children 2 Biological Beginnings John W. Santrock

  2. Biological Beginnings • What Is the Evolutionary Perspective? • What Are the Genetic Foundations of Development? • What Are Some Reproductive Challenges and Choices? • How Do Heredity and Environment Interact? The Nature-Nurture Debate

  3. What Is the Evolutionary Perspective? Natural Selection and Adaptive Behavior • Stories of the Jim and Jim Twins • Identical twins separated after birth • Identical lifestyles after 39 years apart • Part of Minnesota Study of Twins Reared Apart; other twin sets with similar outcomes

  4. What Is the Evolutionary Perspective? Natural Selection and Adaptive Behavior • Natural selection: evolutionary process favors individuals best adapted to survive and reproduce • Evolutionary psychology: emphasizes adaptation, reproduction, and “survival of the fittest” in shaping behavior

  5. Evolution can explain our behavior: -Men have better spatial ability -Women use more verbal instances

  6. What Is the Evolutionary Perspective? Evolutionary Psychology • Extended “juvenile” period -> larger brain size • Aspects of childhood prepare for adulthood -> Play • Some childhood characteristics are adaptive at specific points in life -> Play to adapt to current environment • Psychological mechanisms evolved as domain-specific -> modular brain

  7. What Is the Evolutionary Perspective? Evaluating Evolutionary Psychology • Bidirectional view • Evolution gives bodily structures and biological potentials; does not dictate behavior • Biology allows broad range of cultural possibilities

  8. From a single cell to trillions of cells

  9. Chromosomes Cell 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. 2.2 Cells, Chromosomes, Genes, and DNA

  10. What Are the Genetic Foundations of Development? The Genetic Process • DNA and the Collaborative Gene • Chromosomes: threadlike structures that come in 23 pairs, one member of each pair coming from each parent • DNA: complex molecule; double helix • Genes: units of heredity • Human have only about 30,000 genes

  11. Collaborative Genes • Genes are short segments of DNA and direct cells to reproduce themselves and to assemble protein. • Human have far more protein than genes. • Many genes collaborate with each other and with non-genetic factors in the environment and this collaboration happens at any point. • A gene maybe turned on because of the environment

  12. Genes and Chromosomes http://www.youtube.com/watch?v=er8dAhfM9pA

  13. How do genes manage? • Mitosis: all cells have 46 chromosomes in their nucleus, • cell’s nucleus duplicates itself Mitosis http://www.youtube.com/watch?v=JHRBJgq50dk&feature=related

  14. What Are the Genetic Foundations of Development? How do genes manage? • Mitosis, Meiosis, and Fertilization • Meiosis: cell division to form eggs and sperm (or gametes) • cells from ovaries or testes duplicates, but then divides twice, forming four cells • Each cell has 23 unpaired chromosomes http://www.youtube.com/watch?v=D1_-mQS_FZ0&feature=related

  15. What Are the Genetic Foundations of Development? The Genetic Process • Mitosis, Meiosis, and Fertilization • Reproduction: begins when female gamete (ovum) fertilized by male gamete (sperm) • Zygote: single cell formed through fertilization; 23 pairs of chromosomes • X and Y chromosomes

  16. What Are the Genetic Foundations of Development? The Genetic Difference Between Males and Females

  17. http://www.youtube.com/watch?v=r0byeqI0FRg&feature=related

  18. What Are the Genetic Foundations of Development? The Genetic Process • Sources of Variability • A zygot is not a replica of mom and dad’s genes • Identical and fraternal twins • Mutated gene • Genotype: genetic heritage • Phenotype: genotype expressed in observed and measurable characteristics

  19. What Are the Genetic Foundations of Development? Genetic Principles • Dominant-Recessive Genes Principle • Recessive gene is influential only if both genes are recessive

  20. Genetic Principles

  21. What Are the Genetic Foundations of Development? Chromosome Abnormalities • Chromosome abnormalities: gamete does not have normal set of 23 • Down syndrome: extra copy of chromosome #21 mental retardation

  22. Klinefelter syndrome Disorder in males; extra X chromosome undeveloped testes and enlarged breast Fragile X syndrome Abnormality in X chromosome; becomes constricted or breaks; mental deficiency, learning disabilities, more prominent in male Turner syndrome Female disorder; X chromosome missing Or partially deleted, infertility, lack of math ability XYY syndrome Disorder in males; extra Y chromosome no evidence for more aggression What Are the Genetic Foundations of Development? Sex-Linked Chromosome Abnormalities

  23. What Are the Genetic Foundations of Development? Gene-Linked AbnormalitiesHarmful Genes • Phenylketonuria (PKU): individual cannot properly metabolize an amino acid; easily detected and prevented • It is a result of a recessive gene • Sickle-cell anemia: affects red blood cells; recessive gene influence, 1 in 10 African American carries it

  24. What Are Some Reproductive Challenges and Choices? Prenatal Diagnostic Tests • Ultrasound sonography: high-frequency sound waves directed into abdomen, can detect abnormal structures • Chorionic villi sampling: sample of the placenta • Amniocentesis: sample of amniotic fluid • Maternal blood or triple screening

  25. What Are Some Reproductive Challenges and Choices? Infertility and Reproduction Technology • Infertility: inability to conceive after 12 months of regular intercourse • In vitro fertilization (IVF) • Gamete intrafallopian transfer (GIFT) • Zygote intrafallopian transfer (ZIFT)

  26. How Do Heredity and Environment Interact? The Nature-Nurture Debate Behavior Genetics • Behavior genetics: influence of heredity and environment on individual trait and developmental differences

  27. How Do Heredity and Environment Interact? The Nature-Nurture Debate Behavior Genetics • Twin studies: compare behavioral similarity of identical (monozygotic) twins with behavioral similarity of fraternal (dizygotic) twins • Adoption studies: discover whether adopted children are more like adoptive parents or biological parents

  28. How Do Heredity and Environment Interact? The Nature-Nurture Debate Heredity-Environment Correlations • Heredity-environment interaction has complexities • Individuals influence environments, yet individuals “inherit” environments • The three genotype-environment correlations change as children grow

  29. Passive When natural parents provide rearingenvironment Evocative When genotype elicits certain types of physicaland social environments Active (niche-picking) When children seek out compatible andstimulating environments How Do Heredity and Environment Interact? The Nature-Nurture Debate Genotype-Environment Correlations

  30. How Do Heredity and Environment Interact? The Nature-Nurture Debate Shared and Nonshared Environmental Experiences • Shared environmental experiences: Siblings’ common experiences • Parents’ personalities • Intellectual orientation • Family’s socioeconomic status • Neighborhood

  31. How Do Heredity and Environment Interact? The Nature-Nurture Debate Shared and Nonshared Environmental Experiences • Nonshared environmental experiences; the unique child • Within family • Outside family • Not shared by another sibling

  32. Shared environments play a little accounts for little of the variations in children’s personality or interest. • Heredity influences the non-shared environments of the siblings • Judith Harris “The Nature Assumption”

  33. How Do Heredity and Environment Interact? The Nature-Nurture Debate Conclusions About Heredity-Environment Interaction • Operate cooperatively • Relative contributions are not additive • Many complex behaviors have some genetic loading

  34. Children 2 The End

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