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THE START OF LIFE: PRENATAL DEVELOPMENT

Delve into the fascinating realm of prenatal development, from the fusion of gametes to the complexities of genetic inheritance. Explore the interplay between heredity and environment in shaping human life, uncovering the mysteries of genetic codes and their role in determining traits and disorders. Gain insights into the multifaceted factors influencing intelligence and the nuances of gene expression under varying environmental conditions.

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THE START OF LIFE: PRENATAL DEVELOPMENT

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  1. Chapter 2 THE START OF LIFE: PRENATAL DEVELOPMENT

  2. Background • I did not select this text • This is the first time I’ve used it • I apologize for the selection and for the author • This class is not a course in politics or religion. • Your grade in this class will NOT be based on • Repeating my political views • Repeating the author’s political views • Anyone’s Ideology • To the extent possible, this course will be about Science. The Science of human development. Therefore there will be entire sections of chapters we will not cover. For this course Statement of Intent

  3. The text contains considerable material which may be of interest to various professions but does not seem to be a part of developmental psychology. Topics like IVF, government policy, testing, abortion, and the like will not be covered in class as their connection to development is tenuous. Students with questions about this material may ask questions in class or contact me outside of the classroom. Let’s chat about what I’m leaving out. Do you get this material in other classes? For this course Statement of Intent cont.

  4. My Observation on Observational Methodology • Based on discussion w/ my spouse during our trip • Un(der?)-reported Observational Method Error • Author makes this error • People make this error • Behavior is observed • Behavior is recorded and reported • Behavior is ascribed to a cause. • However, the actual cause is • Not observable • Unknown based on observation • Observation alone does not disclose causation Of course, “everybody knows” that observational research is correlational but…

  5. EARLIEST DEVELOPMENT

  6. Beginning of Life • Gametes from male and female join • ovum • sperm • Fused gametes create zygote • Resulting combination of their genetic instructions is sufficient to begin creation of human life

  7. Contents of a Single Human Cell # changes fairly regularly • Genes • Specific DNA sequences • Chromosomes • Rod-shaped DNA portions in 23 pairs • Contain genetic blueprint for individuals • Replicate through mitosis

  8. Other Conception Mechanisms • Think of reproduction at the cellular level as a kind of war between reproducing organisms. • Each “wants” to pass on the most information • Females have advantage via the egg which contributes all of an animal’s mitochondrial genes – well, usually • Result: • Ovum “selects” sperm to use • Sperm “regulates” gene expression in the egg

  9. Multiple Births: Two-or More-for the Genetic Price of One There are different kinds of multiple births • Monozygotic • Dizygotic • Trizygotic and so on… Causes of multiple births • Fertility drugs • Environmental agents? • Racial, ethnic, and national (?) differences • Family, e.g. inherited predilection

  10. Lousy chart Note nonlinear scale Rising Multiples

  11. Establishing the Sex of the Child Also XXY and other abnormalities

  12. Mixing and Matching of Genes Basics of genetics • Dominant traits • Trait that is expressed when dominant gene is present • Expressed even if paired with a recessive gene Notation uses a capital letter (B) • Recessive traits • Trait not expressed when a dominant gene is present • Expressed only if paired w/ same recessive gene Notation uses a lower case letter (b) • Polygenic traits • Expression controlled by multiple genes • Complex gene interaction • Neither Dominant or Recessive - like blood types (AB)

  13. Just the right type Genotype Underlying genetic material but not outwardly visible. Some genes “pair up” forming alleles – alternate forms • Homozygous • 2 similar forms of the gene (BB or bb) • Heterozygous • 2 different forms of the gene (Bb or bB) Phenotype Observable trait

  14. Genetic Information Transmission

  15. Cracking the Genetic Code • The Human Genome • National Human Genome Research Institute • http://www.genome.gov/ Humans less variable than any other primate. Northern Europeans have Neanderthal genes. Asians have Denisovan genes. Africans have only human genes. Highly Misleading

  16. Information from the Human Genome Project& Private Research

  17. Current Understanding of the Genetic Basis of Some Disorders and Traits

  18. When Development Deviates from the Norm

  19. THE INTERACTION OF HEREDITY AND ENVIRONMENT

  20. Role of the Environment in Determining the Expression of Genes: From Genotypes to Phenotypes Given behavior is not caused just by genetic factors; nor is it caused solely by environmental forces • Multifactorial transmission • Genotype provides a range of possible outcomes • Environment chooses a value in the range • Some genotypes sensitive to environment • Some genotypes unaffected by environment • One example is stress of mother during pregnancy

  21. Range of Possibilities: Determinants of Intelligence • It is reasonable to believe that: • Plasticity or sensitivity to environmental mitigation varies between individuals. • Mitigation effects may have varying permanency. • Mitigation effects may have ‘critical periods’.

  22. Studying DevelopmentHow Much Is Development? How Much Is Nature? Nonhuman animal studies • Controlling genetics and environment • Same genetics different environments • Different genetics same environment Human studies • Adoption • Identical & non-identical twins • Twin studies • Not without bias due to adoption agency placement policy • Family studies • Unrelated children same family environment • Genetic similarity between parents and children

  23. Do you have your mother's eyes?And other lies about genetics found in textbooks Family resemblances • More genetically similarity  more likely to share physical characteristics • Obesity, blood pressure, respiration rates, age at death • Eye color • Hair color • Height • Muscle structure • And so forth Myths of Human Genetics Required reading

  24. Nature, Nurture, and Intelligence • Relative contributions of nature & nurture highly studied • Relative contributions highly politicized • Closer genetic link => higher relation of overall IQ scores • Controversy over measurement methods • Northeast vs. Southeast • Race • Immigrants • Urban vs. Rural

  25. Genetics and I.Q. Note: IQ is actually far more complex than a single score on a paper test.

  26. Do we inherit our personality?

  27. Genetic and Environmental Influence on Personality: Born to Be Outgoing?

  28. What evidence supports this claim?

  29. Psychological Disorders: The Role of Genetics and the Environment • Culture • Parental encouragement Can you think of any others?

  30. Developmental Diversity Can a culture's philosophical outlook be determined by genetics? Are there “good” and “bad” cultures? Not Relevant

  31. Mean Behavioral Scores for Caucasian American, Irish, and Chinese 4-Month-Old Infants

  32. The Genetics of Schizophrenia

  33. Fundamental Principle Within debate about relative influence of nature and nurture • Role of genetics is often to • produce tendency toward future course of development • Bound possible range • Role of environment affects when and whether a certain behavioral characteristic will actually be displayed • Direct control • Interactive control

  34. Can Genes Influence the Environment? Sandra Scarrsuggests three ways child's genetic predisposition may influence his or her environment: • Active • Passive • Evocative

  35. PRENATAL GROWTH AND CHANGE

  36. Fertilization: The Moment of Conception Germinal

  37. Stages of Prenatal Development • Germinal • Fertilization thru implantation • Embryonic • Fetal The Visible Embryo is a visual guide through fetal development from fertilization through pregnancy to birth. http://www.visembryo.com/baby/index.html

  38. Stages of the Prenatal Period

  39. Germinal Stage Fertilization  two weeks • Shortest stage • During the first few cellular divisions, a zygote is properly called a morula, or mass of cells. • At 3 days zygote has 32 cells • A zygote undergoes cellular division for four days. • On the fifth day it forms a blastocyst. • Blastocyst • inner cell mass, or embryoblast, which forms the embryo • outer layer of cells, or trophoblast, surrounds the inner cell mass • fluid-filled cavity known as the blastocoele. • The human blastocyst has 70-100 cells.

  40. Germinal Stage Continued Fertilization  two weeks • Blastocyst continued: • Travels to and implants in uterus • Characterized by methodical cell division • With division comes cell specialization

  41. Embryonic Stage 2 weeks  8 weeks • Organism firmly secures to uterus and is called an embryo • Development of major organs and basic anatomy Three distinct layers that forms different structures • Ectoderm • Endoderm • Mesoderm

  42. Body Proportions

  43. Fetal Stage 8 weeks  Birth • Formally starts when differentiation of major organs has occurred • Organism now called fetus • Characterized by rapid development • Organs become more differentiated and begin working • Interconnections between body parents become more complex and integrated • Brain becomes more sophisticated

  44. Older Women and Risks of Pregnancy Note dissimilar scales making comparisons confusing

  45. Threats to Development Prenatal environment: Enter at your own risk! • Teratogens • Recreational Drugs: Heroin, Cocaine, and Crack • Prescribed Drugs: Thalidomide, SSRIs, many more! • Alcohol • Smoking • Caffeine • Low Birth Weight • Rarely - physical injury, radiation, Excellent review on Wikipedia : http://en.wikipedia.org/wiki/Teratology

  46. Teratogen Sensitivity Timeline

  47. Mother's Prenatal Influence • Diet • Age • Prenatal support • Health • Drug use • Alcohol use • Fetal alcohol syndrome (FAS) • Fetal alcohol effects (FAE) • Tobacco use • Plasticizers & other hormone mimics (BisphenolA - BPA) • List of estrogen mimics

  48. Father's Prenatal Influence • Relatively little research • Tobacco use • Drug use • Cocaine use harmful because tiny specks of cocaine can bind to sperm and “piggyback” their way into the zygote • Marijuana • Alcohol damages sperm, increases maternal stress • Treatment of mother

  49. Becoming an Informed ConsumerOptimizing the Prenatal Environment • Avoid X-rays & birth control pills • Get rubella vaccination • Eat well and take prenatal vitamins • Avoid alcohol and other drugs • Avoid men who are alcohol or drug users • Monitor caffeine intake • Avoid smoking & exposure to secondhand smoke • Exercise regularly

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