Chapter 2

1. Chapter 2 Biological Beginnings PowerPoints developed by Nicholas Greco IV, College of Lake County, Grayslake, IL (c) 2012 The McGraw-Hill Companies, Inc.

2. The Evolutionary Perspective • Natural Selection and Adaptive Behavior • natural selection -- the evolutionary process by which those individuals of a species that are best adapted are the ones that survive and reproduce • survivors are better adapted to their world than are the non-survivors (Darwin, 1859; Johnson & Losos, 2008) (c) 2012 The McGraw-Hill Companies, Inc.

3. Evolutionary Psychology • Emphasizes the importance of adaptation, reproduction, and “survival of the fittest” in shaping behavior • Fit -- the ability to bear offspring that survive long enough to bear offspring of their own • the ability to pass your genes to the next generation(Promislow, Fedorka, & Burger, 2006) (c) 2012 The McGraw-Hill Companies, Inc.

4. Evolutionary Developmental Psychology • Humans take longer to become reproductively mature • Humans require time to develop a large brain and learn the complexity of human societies • Thus, length of childhood period is extended • Evolved mechanisms are not always adaptive in contemporary society (c) 2012 The McGraw-Hill Companies, Inc.

5. Evaluating Evolutionary Psychology • Bandura (1998) rejects what he calls “one-sided evolutionism” • An alternative is a bidirectionalview, in which environmental and biological conditions influence each other • Evolution gave us bodily structures and biological potentialities • People have used their biological capacities to produce diverse cultures -- aggressive and pacific, egalitarian and autocratic (c) 2012 The McGraw-Hill Companies, Inc.

6. Genetic Foundations of Development • Each of us carries a “genetic code” that we inherited from our parents • A fertilized human egg carries this human code • Fertilized human egg cannot grow into any other species • Each of us began life as a single cell which contained our entire genetic code (c) 2012 The McGraw-Hill Companies, Inc.

7. Chromosomes • Nucleus of each human cell contains chromosomes • Chromosomes -- thread-like structures made up of deoxyribonucleic acid, or DNA • DNA is a complex molecule that has a double helix shape, like a spiral staircase, and contains genetic information (c) 2012 The McGraw-Hill Companies, Inc.

8. Genes • Genes -- units of hereditary information • short segments of DNA • Genes direct cells to reproduce themselves and to assemble proteins • Proteins • the building blocks of cells • the regulators that direct the body’s processes (Mader, 2008) (c) 2012 The McGraw-Hill Companies, Inc.

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10. Human Genome Project • Preliminary map of the human genome -- the complete set of developmental instructions for creating proteins that initiate the making of a human organism • Each human has approximately 20,500 genes • Human genome consists of many genes that collaborate both with each other and with non-genetic factors inside and outside the body • Genetic expression is affected by their environment (c) 2012 The McGraw-Hill Companies, Inc.

11. Mitosis • All body cells, except the sperm and egg, have 46 chromosomes arranged in 23 pairs • Body cells reproduce by a process called mitosis • During mitosis, the cell’s nucleus—including the chromosomes—duplicates itself and the cell divides • Two new cells are formed, each containing the same DNA as the original cell (c) 2012 The McGraw-Hill Companies, Inc.

12. Meiosis • Sex cell division is different type of cell division • Eggs and sperm (or gametes) are formed in meiosis • A cell of the testes (in men) or ovaries (in women) duplicates its chromosomes but then divides twice, thus forming four cells • Each of these has only half of the genetic material of the parent cell • By the end of meiosis, each egg or sperm has 23 unpairedchromosomes (c) 2012 The McGraw-Hill Companies, Inc.

13. Fertilization • Zygote -- an egg and a sperm fuse to create a single cell • In the zygote, the 23 unpaired chromosomes from the egg and sperm combine to form one set of 23 paired chromosomes • One chromosome of each pair is from the mother’s egg and the other from the father’s sperm • Each parent contributes half of the offspring’s genetic material (c) 2012 The McGraw-Hill Companies, Inc.

14. The 23rd Pair of Chromosomes • Slight difference in the 23rd pair • In females, the 23rd pair consists of two chromosomes called X chromosomes • In males, the 23rd pair consists of an X and a Y chromosome • The presence of a Y chromosome is what makes an individual male (c) 2012 The McGraw-Hill Companies, Inc.

15. Sources of Variability • Combining genes of two parents increases genetic variability in the population • Chromosomes in the zygote are not exact copies of the parents • Another source of variability comes from DNA • mutated gene -- a permanently altered segment of DNA (c) 2012 The McGraw-Hill Companies, Inc.

16. Genotype and Phenotype • Genotype -- all of a person’s genetic material • Phenotype -- observable characteristics • Phenotypes include • physical characteristics (such as height, weight, and hair color) • psychological characteristics (such as personality and intelligence) (c) 2012 The McGraw-Hill Companies, Inc.

17. Dominant-Recessive Genes Principle • Dominant -- one gene of a pair always exerts its effects • Recessive gene -- exerts its influence only if the two genes of a pair are both recessive • may be overridden by a dominant gene • may be carried from generation to generation but not expressed in phenotype (c) 2012 The McGraw-Hill Companies, Inc.

18. Sex-Linked Genes • X-linked inheritance -- mutated gene is carried on the X chromosome • males have no “backup” copy to counter the harmful gene • females have a second X chromosome, which is likely to be unchanged • Females who have one changed copy of the X gene are known as “carriers” (Turner, 2006) (c) 2012 The McGraw-Hill Companies, Inc.

19. Polygenic Inheritance • Genetic transmission is usually quite complex • few characteristics reflect the influence of only a single gene or pair of genes • Polygenically determined characteristics -- determined by the interaction of many different genes (c) 2012 The McGraw-Hill Companies, Inc.

20. Chromosome- and Gene-Linked Abnormalities • Down syndrome -- caused by the presence of an extra copy of chromosome 21 • once in every 700 live births • women aged 16 - 34 are less likely to give birth to a child with Down syndrome (c) 2012 The McGraw-Hill Companies, Inc.

21. Sex-Linked Chromosome Abnormalities • Klinefelter syndrome -- extra X chromosome • Fragile X syndrome -- results from an abnormality in the X chromosome • X chromosome becomes constricted and often breaks • Turner syndrome -- females have either an X chromosome missing or part of one X chromosome is deleted • XYY syndrome -- male has extra Y (c) 2012 The McGraw-Hill Companies, Inc.

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23. Gene-Linked Abnormalities • Phenylketonuria (PKU) -- individual cannot properly metabolize phenylalanine, an amino acid • left untreated, phenylalanine builds up in the child, producing mental retardation and hyperactivity • Sickle-cell anemia -- genetic disorder that impairs the body’s red blood cells • most often in African Americans • red blood cell becomes a hook-shaped “sickle” that cannot carry oxygen properly (c) 2012 The McGraw-Hill Companies, Inc.

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25. Other diseases that result from genetic abnormalities • Cystic fibrosis • Diabetes • Hemophilia • Huntington disease • Spina bifida • Tay-Sachs disease (c) 2012 The McGraw-Hill Companies, Inc.

26. Behavior Genetics • Behavior genetics seeks to discover the influence of heredity and environment on individual differences in human traits and development • Behavior geneticists often study either twins or adoption situations (Plomin, DeFries, & Fulker, 2007; Vogler, 2006) (c) 2012 The McGraw-Hill Companies, Inc.

27. Behavior Genetics • In a twin study, the behavioral similarities between identical twins is compared with the behavioral similarities between fraternal twins • In an adoption study, investigators seek to discover whether the behavior and psychological characteristics of adopted children are more like those of their adopted parents (c) 2012 The McGraw-Hill Companies, Inc.

28. Heredity-Environment Correlations • Passive genotype-environment correlations occur because biological parents, who are genetically related to the child, provide a rearing environment for the child • Evocative genotype-environment correlations occur because a child’s characteristics elicit certain types of environments (c) 2012 The McGraw-Hill Companies, Inc.

29. Heredity-Environment Correlations • Active (niche-picking) genotype-environment correlations occur when children seek out environments that they find compatible and stimulating • Niche-picking refers to finding a setting that is suited to one’s abilities (c) 2012 The McGraw-Hill Companies, Inc.

30. The Epigenetic View • Development is the result of an ongoing, bidirectional interchange between heredity and the environment • Heredity and environment operate together—or collaborate—to produce a person’s intelligence, temperament, height, weight, ability to pitch a baseball, ability to read, etc. (Gottlieb, Wahlsten, & Lickliter, 2006) (c) 2012 The McGraw-Hill Companies, Inc.

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32. Gene X Environment (G x E) Interaction • The interaction of a specific measured variation in DNA and a specific measured aspect of the environment (c) 2012 The McGraw-Hill Companies, Inc.

33. The Course of Prenatal Development • Fertilization to birth • Prenatal development lasts approximately 266 days • Three periods • Germinal • Embryonic • Fetal (c) 2012 The McGraw-Hill Companies, Inc.

34. The Germinal Period • First two weeks after conception • Creation of the fertilized egg (the zygote) • Cell division • Attachment of the zygote to the uterine wall (c) 2012 The McGraw-Hill Companies, Inc.

35. The Germinal Period • Blastocyst -- consists of an inner mass of cells that will eventually develop into the embryo • Trophoblast -- outer layer of cells that later provides nutrition and support for the embryo • Implantation -- the attachment of the zygote to the uterine wall • takes place about 10 to 14 days after conception (c) 2012 The McGraw-Hill Companies, Inc.

36. The Embryonic Period • Occurs from two to eight weeks after conception • Rate of cell differentiation intensifies • Begins as the blastocyst attaches to the uterine wall • Every body part eventually develops from these three layers • endoderm • ectoderm • mesoderm (c) 2012 The McGraw-Hill Companies, Inc.

37. The Embryonic Period • The mass of cells is an embryo • Organogenesis -- the process of organ formation during the first two months of prenatal development • organs are especially vulnerable to environmental influences • Life-support systems for the embryo develop rapidly (c) 2012 The McGraw-Hill Companies, Inc.

38. Life-Support Systems for the Embryo • Amnion -- bag containing a clear fluid in which the developing embryo floats • Umbilical cord contains two arteries and one vein and connects the baby to the placenta • Placenta consists of a disk-shaped group of tissues in which small blood vessels from the mother and the offspring intertwine but do not join (c) 2012 The McGraw-Hill Companies, Inc.

39. The Fetal Period • Fetal period begins two months after conception and lasts for seven months • Three months after conception -- fetus is about 3 inches long; weighs about 3 ounces • By the end of the fifth month, the fetus is about 12 inches long and weighs close to a pound • At birth, the average American baby weighs 7½ pounds and is about 20 inches long (c) 2012 The McGraw-Hill Companies, Inc.

40. The Fetal Period • See Figure 2.8 on page 48 (c) 2012 The McGraw-Hill Companies, Inc.

41. Three Trimesters • The germinal and embryonic periods occur in the first trimester • The fetal period begins toward the end of the first trimester and continues through the second and third trimesters • Viability (the chances of surviving outside the womb) occurs at the beginning of the third trimester • About 24-25 weeks after conception (c) 2012 The McGraw-Hill Companies, Inc.

42. The Brain • By the time babies are born, they have approximately 100 billion neurons • The basic architecture of the brain is assembled during the first two trimesters • The third trimester and the first two years of postnatal life are characterized by connectivity and functioning of neurons (c) 2012 The McGraw-Hill Companies, Inc.

43. The Brain • The neural tube develops out of the ectoderm and forms at about 18 to 24 days after conception • Two birth defects related to the failure of the neural tube to close are: • Anencephaly • Spina bifida • Folic acid may prevent neural tube defects (c) 2012 The McGraw-Hill Companies, Inc.

44. The Brain • The generation of new neurons is called neurogenesis • Neuronal migration occurs at 6-24 weeks after conception • At about the 23rd prenatal week, connections between neurons begin to form (c) 2012 The McGraw-Hill Companies, Inc.

45. Prenatal Tests • Ultrasound sonography • non-invasive • high-frequency sound waves • Fetal MRI • Used to obtain more detailed images than ultrasound • Chorionic villus sampling (CVS) • tiny tissue sample from the placenta is removed and analyzed • Amniocentesis • sample of amniotic fluid is withdrawn and tested for chromosome or metabolic disorders (c) 2012 The McGraw-Hill Companies, Inc.

46. Prenatal Tests • Maternal blood screening • Identifies pregnancies that have an elevated risk for birth defects such as spina bifida and Down syndrome • Triple Screen • Measures three substances in the mother’s blood • If abnormal, ultrasound is performed, then amniocentesis (c) 2012 The McGraw-Hill Companies, Inc.

47. Infertility and Reproductive Technology • Approximately 10-15 couples in the United States experience infertility • Defined as the inability to conceive a child after 12 months of regular intercourse without conception • In vitro fertilization (IVF) • 25 to 30 percent of pregnancies achieved by fertility treatments result in multiple births (c) 2012 The McGraw-Hill Companies, Inc.

48. Hazards to Prenatal Development • A teratogen is any agent that can potentially cause a birth defect or negatively alter cognitive and behavioral outcomes • Drugs • Incompatible blood types • Environmental pollutants • Infectious diseases • Maternal stress, advanced maternal and paternal age (c) 2012 The McGraw-Hill Companies, Inc.

49. Hazards to Prenatal Development • The dose, genetic susceptibility, and the time of exposure influence both the severity of damage to an embryo or fetus and the type of defect (c) 2012 The McGraw-Hill Companies, Inc.

50. Hazards to Prenatal Development • Prescription drugs • Antibiotics • Antidepressants • Hormones • Accutane • Psychoactive drugs • Caffeine • Alcohol (Fetal alcohol spectrum disorders, FASD) • Nicotine • Cocaine • Methamphetamine • Marijuana • Heroin (c) 2012 The McGraw-Hill Companies, Inc.