Chapter 3

1. Chapter 3 Biological Beginnings ©2005 McGraw-Hill Ryerson Ltd.

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3. The Evolutionary Perspective ©2005 McGraw-Hill Ryerson Ltd.

4. Natural Selection • Natural selection is the evolutionary process that favours individuals of a species that are more adapted to survive and reproduce. ©2005 McGraw-Hill Ryerson Ltd.

5. Adaptive Behaviour • Adaptive behaviour is behaviour that promotes an organism’s survival in the natural habitat. • It involves the organism’s modification of its behaviour to include its likelihood of survival. • All organisms must adapt to particular places, climates, food sources, and ways of life. • Attachment is a system designed by natural selection to ensure a human infant’s closeness to the caregiver for feeding and protection from danger. ©2005 McGraw-Hill Ryerson Ltd.

6. Charles Darwin • Observed that most organisms reproduce at tremendous rates, yet populations remain nearly constant. • Reasoned that an intense, constant struggle for food, water, and recourses must occur among the numerous young born. • Theorized that survivors pass on their genes to the next generation. • Believed that those who survive are superior to those who do not. ©2005 McGraw-Hill Ryerson Ltd.

7. Evolutionary Psychology • This branch of psychology emphasizes the importance of adaptation, reproduction, and “survival of the fittest” in explaining behaviour. • It focuses on conditions that allow individuals to survive or to fail. • It believes natural selection favours behaviours that increase organisms’ reproductive success and their ability to pass their genes on the next generation. • David Buss believes that evolution shapes both our physical features and pervasively influences how we make decisions, how aggressive we are, our fears, and our mating patterns. ©2005 McGraw-Hill Ryerson Ltd.

8. Evolution and Life-Span Development • Developmentalist Paul Baltes believes that the benefits of evolutionary selection decrease with age. • He also believes that the need for culture increases with age. ©2005 McGraw-Hill Ryerson Ltd.

9. Evaluating Evolutionary Psychology • Social cognitive theorist Albert Bandura acknowledges evolution’s important role in human adaptation and change, but argues for a bi-directional view that enables organisms to alter and construct new environmental conditions. • Biology allows for a broad range of cultural possibilities. ©2005 McGraw-Hill Ryerson Ltd.

10. Genetic Foundations • Each of us carries a genetic code that we inherited from our parents. • This code is located within every cell in our bodies. • The code is the mechanism for transmitting characteristics from one generation to the next. ©2005 McGraw-Hill Ryerson Ltd.

11. Genetic Building Blocks • DNA • Genes • Chromosomes ©2005 McGraw-Hill Ryerson Ltd.

12. Definition of DNA • Deoxyribonucleic acid is a complex molecule, shaped like a double helix, that contains genetic information. ©2005 McGraw-Hill Ryerson Ltd.

13. What Are Genes? • The units of hereditary information – short segments composed of DNA – that act as blueprints for cells to reproduce themselves and manufacture the proteins that maintain life. ©2005 McGraw-Hill Ryerson Ltd.

14. Definition of Chromosomes • Threadlike structures composed of thousands of genes that come in 23 pairs, one member of each pair coming from each parent. ©2005 McGraw-Hill Ryerson Ltd.

15. Mitosis and Meiosis • Mitosis is the process by which each chromosome in the cell’s nucleus duplicates itself. • Meiosis is the process by which cells divide into gametes (testes/sperm in males, ovaries/eggs in females), which have half the genetic material of the parent cell. ©2005 McGraw-Hill Ryerson Ltd.

16. The Process of Human Reproduction • Reproduction begins when a female gamete (ovum) is fertilized by a male gamete (sperm). • This produces a zygote – a single cell formed through fertilization. • In the zygote, two sets of unpaired chromosomes combine to form one set of paired chromosomes. ©2005 McGraw-Hill Ryerson Ltd.

17. Genetic Principles • Dominate-recessive genes principle • Sex-linked genes • Polygenically inherited characteristics • Reaction range • Canalization ©2005 McGraw-Hill Ryerson Ltd.

18. Dominate-Recessive Genes Principle • If one gene of a pair is dominant and one is recessive, the dominant gene exerts its effect, overriding the potential influence of the other, recessive gene. • A recessive gene exerts its influence only if the two genes of a pair are both recessive. ©2005 McGraw-Hill Ryerson Ltd.

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21. Sex-Linked Genes • Two of the 46 chromosomes human beings normally carry are sex chromosomes. • Ordinarily females have two X chromosomes and males have an X and a Y. ©2005 McGraw-Hill Ryerson Ltd.

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23. Polygenic Inheritance • The genetic principle that many genes can interact to produce a particular characteristic. • There are more than 50,000 genes. Imagine the possible combinations! ©2005 McGraw-Hill Ryerson Ltd.

24. Genotypes and Phenotypes • Genotype – an individual’s genetic heritage, the actual genetic material. • Phenotype – the way an individual’s genotype is expressed in observed and measurable characteristics. • Physical traits: height, weight, eye colour • Psychological characteristics: intelligence, creativity, personality • For each genotype, a range of phenotypes can be expressed. ©2005 McGraw-Hill Ryerson Ltd.

25. Reaction Range • Reaction range is the range of possible phenotypes for each genotype, suggesting the importance of an environment’s restrictiveness or richness. ©2005 McGraw-Hill Ryerson Ltd.

26. Canalization • Canalization is the term chosen to describe the narrow path, or developmental course, that certain characteristics take. • Preservative forces help protect or buffer a person from environmental extremes. ©2005 McGraw-Hill Ryerson Ltd.

27. Behaviour Genetics • This is the study of the degree and nature of behaviour’s hereditary basis. • It assumes that behaviours are jointly determined by the interaction of heredity and environment. • Behaviour genetics often uses twins or adoption situations to study the influence of heredity on behaviour. ©2005 McGraw-Hill Ryerson Ltd.

28. Twin Studies • The behavioural similarity of identical twins is compared with the behavioural similarity of fraternal twins. • Identical twins (monzygotic twins) develop from a single fertilized egg that splits into two genetically identical replicas, each of which becomes a person. • Fraternal twins (dizigotic twins) develop from separate eggs and separate sperm, making them genetically no more similar than ordinary siblings. ©2005 McGraw-Hill Ryerson Ltd.

29. Issues with Twin Studies • By comparing groups of identical and fraternal twins, behaviour geneticists capitalize on the basic knowledge that identical twins are more similar genetically than are fraternal twins. • However, adults might stress the similarities of identical twins more than those of fraternal twins. • Identical twins might perceive themselves as a “set” and play together more than fraternal twins. ©2005 McGraw-Hill Ryerson Ltd.

30. Adoption Studies • Investigators seek to discover whether, in behaviour and psychological characteristics, adopted children are more like their adoptive parents, who provided a home environment, or more like their biological parents, who contributed their heredity. • Another method is to compare adoptive and biological siblings. ©2005 McGraw-Hill Ryerson Ltd.

31. Molecular Genetics • There is a great deal of enthusiasm about the use of molecular genetics to discover the specific locations on genes that determine an individual’s susceptibility to many diseases and other aspects of health and well-being. ©2005 McGraw-Hill Ryerson Ltd.

32. Genome • The term used to describe the complete set of instructions for making an organism • Contains the master blueprint for all cellular structures and activities for the life span of an organism • The human genome consists of tightly coiled threads of DNA ©2005 McGraw-Hill Ryerson Ltd.

33. Chromosome and Gene-Linked Abnormalities • Chromosomal abnormalities • Down Syndrome • Klinefelter Syndrome • Fragile X Syndrome • Turner Syndrome • XYY Syndrome • Gene-linked abnormalities • Phenylketonuria • Sickle-Cell Anemia • Tay-Sachs Disease ©2005 McGraw-Hill Ryerson Ltd.

34. Down Syndrome • Caused by the presence of an extra chromosome • Characterized by: • Round face • Flattened skull • Extra fold of skin over the eyelids • Protruding tongue • Short limbs • Women younger than 18 and older than 38 are more likely to have Down Syndrome babies ©2005 McGraw-Hill Ryerson Ltd.

35. Klinefelter Syndrome • Sex-linked chromosome abnormality • Males have an extra X chromosome, making them XXY instead of XY • Characterized by • Underdeveloped testes • Enlarged breasts • Above-average height ©2005 McGraw-Hill Ryerson Ltd.

36. Fragile X Syndrome • Sex-linked chromosome abnormality • The X chromosome becomes constricted and often breaks • Characterized by: • Mental deficiency (varied in from mental retardation to short attention span) • Occurs more frequently in males ©2005 McGraw-Hill Ryerson Ltd.

37. Turner Syndrome • Sex-linked chromosome abnormality • Females are missing an X chromosome, making them XO instead of XX • Characterized by: • Shortness of stature • Webbed neck • Possible mental retardation • Possible sexual underdevelopment ©2005 McGraw-Hill Ryerson Ltd.

38. XYY Syndrome • Sex-linked chromosome abnormality • The make has an extra Y chromosome • Early belief surrounding the syndrome was that the extra Y chromosome contributed to male aggression and violence • Researchers have since found that XYY males are no more likely to commit crimes than are XY males ©2005 McGraw-Hill Ryerson Ltd.

39. Phenylketonuria (PKU) • Gene-linked abnormality • The individual cannot properly metabolize an amino acid • Currently easily detected • Treated by diet to prevent an excess accumulation of phenylalanine. • If left untreated it can result in mental retardation and hyperactivity. ©2005 McGraw-Hill Ryerson Ltd.

40. Sickle-Cell Anemia • Gene-linked abnormality • Occurs most often in African Americans • Affects the shape of red blood cells, hindering their ability to carry oxygen to the body’s cells • Results in anemia and early death ©2005 McGraw-Hill Ryerson Ltd.

41. Tay-Sachs Disease (TSD) • Gene-linked abnormality • Fatal genetic disorder that starts in the fetus during pregnancy, becomes clinically apparent when the child is several months old, and causes death, usually by age five ©2005 McGraw-Hill Ryerson Ltd.

42. Other Genetic Abnormalities • Cystic Fibrosis • Diabetes • Hemophilia • Huntington Disease • Spina Bifida ©2005 McGraw-Hill Ryerson Ltd.

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44. Prenatal Diagnostic Tests • Amniocentesis • Ultrasound Sonography • Chorionic Villi Sampling • Maternal Serum Screening ©2005 McGraw-Hill Ryerson Ltd.

45. Amniocentesis • A prenatal medical procedure in which a sample of amniotic fluid is withdrawn by syringe and tested to discover if the fetus is suffering from any chromosomal or metabolic disorders • Performed between the 12th and 16th weeks of pregnancy • There exists a small risk of miscarriage (one in every 200–300) ©2005 McGraw-Hill Ryerson Ltd.

46. Ultrasound Sonography • A prenatal medical procedure in which high-frequency sound waves are directed into the pregnant woman’s abdomen • Echo from the sounds is transformed into a visual representation of the fetus’s inner structures • Able to detect such disorders are microencephaly ©2005 McGraw-Hill Ryerson Ltd.

47. Chorionic Villi Sampling • A prenatal medical procedure in which a small sample of the placenta is removed • Performed between the 8th and 11th week of pregnancy • Provides information about the presence of birth defects • Has a slightly higher risk of miscarriage than amniocentesis ©2005 McGraw-Hill Ryerson Ltd.

48. Maternal Serum Screening • Called the alpha-fetoprotein (AFP) test • A prenatal diagnostic technique used to asses blood alphaprotein level, which is associated with neural-tube defects • Administered between the 14th and 20th weeks of pregnancy ©2005 McGraw-Hill Ryerson Ltd.

49. Infertility • Infertility is the inability to conceive a child after 12 months of regular intercourse. ©2005 McGraw-Hill Ryerson Ltd.

50. Causes of Infertility • Women • Ovulation problems • Antisperm secretions • Blocked fallopian tubes • Endometriosis • Men • Low sperm count • Immobile sperm • Anitbodies against sperm ©2005 McGraw-Hill Ryerson Ltd.