1. 3—Biological Beginnings
The Evolutionary Perspective
The Genetic Foundations of Development
Reproductive Challenges and Choices
Heredity and Environment Interaction: The Nature-Nurture Debate
Summary

2. The Evolutionary Perspective
Natural Selection and Adaptive Behavior
Natural selection is the evolutionary process that favors individuals of a species that are best adapted to survive and reproduce.
Adaptive behavior is behavior that promotes an organism’s survival in the natural habitat.

3. The Evolutionary Perspective
Natural Selection (continued)
Evolutionary Psychology
A contemporary approach that emphasizes the importance of adaptation, reproduction, and “survival of the fittest” in shaping behavior.

4. The Evolutionary Perspective
Natural Selection (continued)
Evolutionary Developmental Psychology
Views proposed by evolutionary developmental psychologists (Bjorklund & Pellegrini, 2002):
An extended “juvenile” period is needed to develop a large brain and learn the complexity of human social communities.
Many aspects of childhood function as preparations for adulthood and were selected over the course of evolution.

5. The Evolutionary Perspective
Natural Selection (continued)
Evolutionary Developmental Psychology (continued)
Some child characteristics were selected to be adaptive at specific points in development and not as preparation for adulthood.
Many evolved psychological mechanisms are domain-specific.
Evolved mechanisms are not always adaptive in contemporary society.

6. The Evolutionary Perspective
The Brain Sizes of Various Primates and Humans in Relation to the Length of the Juvenile Period
Refer to Figure 3.1

7. The Evolutionary Perspective
Natural Selection (continued)
Evaluating Evolutionary Psychology
Bandura sees development as bidirectional.
Evolution gave us body structures and biological potentialities, not behavioral dictates.
In most domains of human functioning, biology allows a broad range of cultural possibilities (Gould, 1998).

8. Review and Reflect: Learning Goal 1
Discuss the evolutionary perspective on development
Review
How can natural selection and adaptive behavior be defined?
What is evolutionary psychology? What are some basic ideas about human development proposed by evolutionary psychologists? How can evolutionary psychology be evaluated?

9. Review and Reflect: Learning Goal 1
Which is more persuasive to you: the views of evolutionary psychologists or their critics? Why?

10. Genetic Foundations The Genetic Process Chromosomes
Threadlike structures that come in 23 pairs, one member of each pair coming from each parent. Chromosomes contain the genetic substance DNA.
DNA (deoxyribonucleic acid)
A complex, double-helix-shaped molecule that contains genetic information.

11. Genetic Foundations The Genetic Process (continued) Genes
Units of hereditary information that are short segments of DNA. They direct cells to reproduce themselves and to assemble proteins, which are the building blocks of cells and regulate the body’s processes.

12. Genetic Foundations Cells, Chromosomes, Genes, and DNA
Refer to Figure 3.2

13. Genetic Foundations Genes and Chromosomes:
Genes get passed from generation to generation through mitosis, meiosis, and fertilization.
Mitosis: The process by which each chromosome in a cell’s nucleus duplicates itself and divides.
Meiosis: The process by which cells in the reproductive organs (sperm in males, eggs in females) duplicate their chromosomes, then divide twice, forming four cells, each having half of the genetic material of the parent cell.

14. Genetic Foundations Mitosis and Meiosis (continued)
By the end of meiosis, each egg or sperm has 23 unpaired chromosomes.
Fertilization: The process in which an egg and a sperm fuse to create a single cell, the zygote.
Zygote: The single cell formed through fertilization; in the zygote, the unpaired chromosomes from the egg and from the sperm combine to form one set of paired chromosomes.

15. Genetic Foundations
Union of Sperm and Egg
Refer to Figure 3.3

16. Genetic Foundations Sources of Variability
Changes during separation and recombination of chromosomes during meiosis
Sex differences on 23rd pair of chromosomes: XX and XY
Genotype: A person’s genetic heritage; the actual genetic material.
Phenotype: The way an individual’s genotype is expressed in observable and measurable characteristics.
Mutated genes: Permanently altered DNA segments.

17. Genetic Foundations The Genetic Difference Between Males and Females
Refer to Figure 3.4

18. Genetic Foundations Genetic Principles
Dominant-Recessive Genes Principle
Some genes are dominant and will always override so-called recessive genes.
Sex-Linked Genes
X-linked inheritance describes inheritance of a mutated gene carried on the X chromosome.
Because males have only one X chromosome, they are more likely than females (who would be carriers) to manifest an X-linked disease.

19. Genetic Foundations Genetic Principles (continued) Genetic Imprinting
Occurs when genes have differing effects depending on whether they are inherited from the mother or the father.
Imprinted genes dominate over genes that have not been imprinted.

20. Genetic Foundations Genetic Principles (continued)
Polygenic Inheritance
The genetic principle by which many genes interact to influence a particular characteristic

21. Genetic Foundations
How Brown-Haired Parents Can Have a Blond-Haired Child
Refer to Figure 3.5

22. Genetic Foundations Chromosome and Gene-Linked Abnormalities
Chromosome Abnormalities
Sometimes when a gamete is formed, the sperm and ovum do not have their normal set of 23 chromosomes.
Down syndrome: A form of mental and motor retardation and abnormalities of physical features caused by the presence of an extra copy of chromosome 21.

23. Genetic Foundations Chromosome Abnormalities (continued)
Sex-Linked Chromosome Abnormalities
Most commonly involve an extra X or Y chromosome or the absence of an X chromosome.
Klinefelter syndrome: Males have an extra X chromosome, making them XXY instead of XY.
Fragile X syndrome: Abnormality in the X chromosome, which becomes constricted and often breaks.

24. Genetic Foundations Chromosome Abnormalities (continued)
Abnormalities of the Sex Chromosomes (continued)
Turner syndrome: Females either lack an X chromosome, making the person XO instead of XX, or the second X chromosome is partially deleted.
The XYY syndrome: Males have an extra Y chromosome.

25. Genetic Foundations
Some Chromosome Abnormalities
Refer to Figure 3.6

26. Genetic Foundations Gene-Linked Abnormalities
Phenylketonuria (PKU): A genetic disorder in which an individual cannot properly metabolize phenylalanine, an amino acid needed for production of proteins in the body. PKU is now easily detected, but if left untreated results in mental retardation and hyperactivity.

27. Genetic Foundations Gene-Linked Abnormalities (continued)
Sickle-cell anemia: A genetic disorder that affects the red blood cells and occurs most often in people of African descent.
Other gene-linked abnormalities: Cystic fibrosis, diabetes, hemophilia, spina bifida, and Tay-Sachs disease.

28. Genetic Foundations
Some Gene-Linked Abnormalities
Refer to Figure 3.7

29. Genetic Foundations Dealing with Genetic Abnormalities
Genes are not destiny.
Missing, nonfunctional, mutated: Gene does not function normally.
Identifying abnormalities can help in suggesting most effective ways to deal with them, but raises concerns about privacy.
Genetic counselors are familiar with these problems, the odds of encountering them, and strategies for offsetting some of their effects.

30. Review and Reflect: Learning Goal 2
Describe what genes are and how they influence human development
Review
How does the genetic process work?
How can the genetic principles of dominant-recessive genes, sex-linked genes, genetic imprinting, and polygenic inheritance be characterized?
What are some chromosome and gene-linked abnormalities?

31. Review and Reflect: Learning Goal 2
What are some possible ethical issues regarding genetics and development that might arise in the future?

32. Reproductive Challenges and Choices
Prenatal Diagnostic Tests
Scientists have developed a number of tests to determine whether a fetus is developing normally.
Ultrasound sonography: High-frequency sound waves are directed into the pregnant woman’s abdomen (7 weeks into pregnancy and beyond; may be used during amniocentesis).
Chorionic villi sampling: A small sample of the placenta is removed (between weeks 8 and 11).

33. Reproductive Challenges and Choices
Prenatal Diagnostic Tests (continued)
Amniocentesis: A sample of amniotic fluid is withdrawn by syringe and tested for chromosomal or metabolic disorders (between weeks 8 and 11).
Maternal blood screening: Triple-screen test measures alpha-fetoprotein (AFP), estriol, and human chorionic gonadotropin to identify risk for birth defects (between weeks 16 and 18).

34. Reproductive Challenges and Choices
Infertility and Reproductive Technology
Infertility: The inability to conceive a child after 12 months of regular intercourse without contraception.
Causes may rest with the woman (not ovulating, abnormal ova, blocked fallopian tubes, disease that prevents implantation) or the man (too few sperm, sperm lack motility, blocked passageway).

35. Reproductive Challenges and Choices
Infertility and Reproductive Technology (continued)
Three common high-tech assisted reproduction techniques:
In vitro fertilization (IVF)
Gamete intrafallopian transfer (GIFT)
Zygote intrafallopian transfer (ZIFT)
Often results in multiple births
Children adjust as well as those who are naturally conceived or adopted

36. Reproductive Challenges and Choices
Success Rates of Three Different Assisted Reproduction Techniques
Refer to Figure 3.8

37. Reproductive Challenges and Choices
Adoption
Adoption: The social and legal process by which a parent-child relationship is established between persons unrelated at birth.
Adopted children and adolescents often show more psychological and school-related problems than nonadopted children, but are also more outgoing and more altruistic; the majority of adopted children adjust effectively.

38. Reproductive Challenges and Choices
Socioemotional Development at Adolescence of Children in Three Family Types: In Vitro Fertilization, Naturally Conceived, and Adopted
Refer to Figure 3.9

39. Review and Reflect: Learning Goal 3
Identify some important reproductive challenges and choices
Review
What are some common prenatal diagnostic tests?
What are some causes of infertility? What types of reproductive technology are used to improve the success rates of having children for infertile couples?
How does adoption affect children’s development?

40. Review and Reflect: Learning Goal 3
We discussed a number of studies indicating that adoption is linked with negative outcomes for children. Does that mean that all adopted children have more negative outcomes than all nonadopted children? Explain.

41. Heredity and Environment Interaction: The Nature-Nurture Debate
Behavior Genetics
Seeks to discover the influence of heredity and environment on individual differences in human traits and development.
To study the link between heredity and behavior, geneticists often use twin studies or adoption studies.

42. Heredity and Environment Interaction
Behavior Genetics (continued)
Twin study: Compares the behavioral similarity of identical (monozygotic) twins with the behavioral similarity of fraternal (dizygotic) twins.
Identical twins develop from a single fertilized egg that splits into two genetically identical replicas.
Fraternal twins develop from separate eggs and separate sperm with no more genetic similarity than ordinary siblings.

43. Heredity and Environment Interaction
Behavior Genetics (continued)
Adoption study: Investigators seek to discover whether the behavior or psychological characteristics of adopted children are more like their adoptive parents (nurture) or their biological parents (nature).

44. Heredity-Environment Interaction
Heredity-Environment Correlations
Individuals’ genes influence the types of environments to which they are exposed.
Passive genotype-environment correlations
Correlations that occur because biological parents provide an environment that matches their own genetic tendencies, and their children inherit genetic tendencies from their parents.

45. Heredity-Environment Interaction
Hereditary-Environment Correlations (continued)
Evocative genotype-environment correlations
Correlations that exist when the child’s genotype elicits certain types of physical and social environments.
Active (niche-picking) genotype-environment correlations
Correlations that exist when children seek out environments they find compatible and stimulating.

46. Heredity-Environment Interaction
Exploring Heredity-Environment Correlations
Refer to Figure 3.10

47. Heredity-Environment Interaction
Shared and Nonshared Environmental Experience
Shared environmental experiences
Children’s common environmental experiences that are shared with their siblings, such as their parents’ personalities and intellectual orientation, the family’s social class, and the neighborhood in which they live.

48. Heredity-Environment Interaction
Shared and Nonshared Environmental Experience (continued)
Nonshared environmental experiences
The child’s unique experiences, both within the family and outside the family, that are not shared by another sibling. Experiences occurring within the family can be part of the “nonshared environment.”

49. Heredity-Environment Interaction
The Epigenetic View
Emphasizes that development is the result of an ongoing, bidirectional interchange between heredity and environment.

50. Heredity-Environment Interaction
Conclusions About Heredity-Environment Interaction
Heredity and environment operate (cooperate) together.
The relative contributions of heredity and environment are not additive.
Emerging view: Many complex behaviors likely have some genetic loading that gives people a propensity for a particular developmental trajectory, but actual development also requires an environment.

51. Heredity-Environment Interaction
Comparison of the Heredity-Environment Correlation and Epigenetic Views
Refer to Figure 3.11

52. Review and Reflect: Learning Goal 4
Characterize some of the ways that heredity and environment interact to produce individual differences in development

53. Review and Reflect: Learning Goal 4
What is behavior genetics?
What are three types of heredity-environment correlations and what is an example of each?
What is meant by the concepts of shared and nonshared experiences?
What is the epigenetic view?
What conclusions can be reached about heredity-environment interaction?

54. Review and Reflect: Learning Goal 4
Someone tells you that he or she has analyzed his or her genetic background and environmental experiences and reached the conclusion that environment definitely has had little influence on his or her intelligence. What would you say to this person about his or her ability to make this self-diagnosis?

55. Summary
Natural selection is the process that favors the individuals of a species that are best adapted to survive and reproduce.
Evolutionary psychology is the view that adaptation, reproduction, and “survival of the fittest” are important in explaining behavior.

56. Summary
The nucleus of each human cell contains 46 chromosomes, which are composed of DNA, and short segments of DNA constitute genes.
Mitosis and meiosis are two ways in which new cells are formed.
In the process of reproduction, an egg and a sperm unite to form a zygote.

57. Summary
Sources of genetic variability distinguish between genotype and phenotype.
Genetic principles include those involving dominant-recessive genes, sex-linked genes, genetic imprinting, and polygenic inheritance.

58. Summary
Chromosomal abnormalities produce Down syndrome as well as sex-linked chromosomal abnormalities.
Gene-linked abnormalities involve harmful genes.
Genetic counseling has increased in popularity as more couples desire information about their risk of having a child with defective characteristics.

59. Summary
Ultrasound sonography, chorionic villi sampling, amniocentesis, and maternal blood screening are used to determine the presence of defects once pregnancy has begun.
Approximately 15% of U.S. couples have infertility problems, some of which can be corrected through surgery or fertility drugs.
Although adopted children and adolescents have more problems than their nonadoptive counterparts, the majority adapt effectively.

60. Summary
Behavior genetics is the field concerned with the degree and nature of behavior’s hereditary basis; major research methods are twin studies and adoption studies.
In Scarr’s heredity-environment correlations view, heredity directs the types of environments children experience: passive, evocative, and active (niche-picking).

61. Summary
Shared environmental experiences refer to siblings’ common experiences, such as their parents’ personalities and intellectual orientation, the family’s socioeconomic status, and the neighborhood in which they live.
Nonshared environmental experiences involve the child’s unique experiences, both within a family and outside a family, that are not shared with a sibling.

62. Summary
The epigenetic view emphasizes that development is the result of an ongoing, bidirectional interchange between heredity and environment.
Many complex behaviors have some genetic loading that gives people a propensity for a particular developmental trajectory, but actual development also requires an environment, and that environment is complex.