John W. Santrock

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