1. Biological Beginnings
Chapter 3
Biological Beginnings

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4. Natural Selection
Natural selection is the evolutionary process that favors individuals of a species that are more adapted to survive and reproduce.
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5. 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 resources must occur among the numerous young born.
Those that survive pass on their genes to the next generation.
Believed that those who survive are superior to those who do not.
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6. Adaptive Behavior
Adaptive behavior is behavior that promotes an organism’s survival in the natural habitat.
It involves the organism’s modification of its behavior to include its likelihood of survival.
All organisms must adapt to particular places, climates, food sources, and ways of life.
Natural selection designs adaptation to perform a certain function.
Attachment is a system designed by natural selection to ensure a human infant’s closeness to the caregiver for feeding and protection from danger.
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7. Evolutionary Psychology
This branch of psychology emphasizes the importance of adaptation, reproduction, and “survival of the fittest” in explaining behavior.
It focuses on conditions that allow individuals to survive or to fail.
It believes natural selection favors behaviors 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.
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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.
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9. The Benefits of Evolutionary Selection Decrease with Age
Selection operates mainly during the first half of life during the period of reproductive fitness.
Given the much shorter life span in early human evolution, selection pressure could not function often in the later years of life.
This results in older adults having a higher number of deleterious genes and dysfunctional gene expressions, such as Alzheimer’s.
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10. The Need for Culture Increases with Age
As older adults weaken biologically, they need culture-based resources, such as cognitive skills, motivation, socialization, literacy, and medical technology.
Baltes stresses that a life span shift in the allocation of resources takes place away from growth and toward maintenance and the regulation of loss.
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11. Evaluating Evolutionary Psychology
Albert Bandura
Steven Jay Gould
Theodore Dobzhansky
The Bidirectional View
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12. Albert Bandura
Acknowledges the important influence of evolution on human adaptation and change
Rejects “one-sided evolutionism”—defining social behavior as the product of evolved biology
Believes the pace of social change gives testimony that biology permits a range of possibilities
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13. Steven Jay Gould
Concluded that in most domains of human functioning, biology allows a broad range of cultural possibilities
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14. Theodore Dobzhansky
Points out that the human species has been selected for learnability and plasticity, allowing us to adapt to diverse contexts rather than have our behavior be biologically fixed
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15. The Bidirectional View
States that evolutionary pressures created changes in biological structures for the use of tools.
This enables organisms to manipulate, alter, and construct new environmental conditions.
Environmental innovations of increasing complexity, in turn, produced new selection pressures for the evolution of specialized biological systems for consciousness, thought, and language.
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17. 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.
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18. Genetic Building Blocks
DNA
Genes
Chromosomes
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19. Definition of DNA
Deoxyribonucleic acid is a complex molecule, shaped like a double helix, that contains genetic information.
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20. What Are Genes?
The units of hereditary information—short segments composed of DNA—that act as a blueprint for cells to reproduce themselves and manufacture the proteins that maintain life.
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21. Definition of Chromosomes
Threadlike structures comprised of thousands of genes, that come in 23 pairs, one member of each pair coming from each parent
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22. 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.
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23. The Difference Between Mitosis and Meiosis
Focus is on cell growth and repair
The number of chromosomes present remains the same (the chromosomes copy themselves)
Two daughter cells are formed
Meiosis
Involves sexual reproduction
The chromosomes are halved
Four daughter cells are produced
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24. 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.
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25. Genetic Principles Dominant-recessive genes principle Sex-linked genes
Polygenically inherited characteristics
Reaction range
Canalization
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26. Dominant-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.
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27. 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.
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28. 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!
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29. 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 color
Psychological characteristics: intelligence, creativity, personality
For each genotype, a range of phenotypes can be expressed.
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30. Reaction Range
Reaction range is the range of possible phenotypes for each genotype, suggesting the importance of an environment’s restrictiveness or richness.
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31. 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.
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32. Behavior Genetics
This is the study of the degree and nature of behavior’s hereditary basis.
It assumes that behaviors are jointly determined by the interaction of heredity and environment.
Behavior genetics often uses twins or adoption situations to study the influence of heredity on behavior.
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33. Twin Studies
The behavioral similarity of identical twins is compared with the behavioral similarity of fraternal twins.
Identical twins (monozygotic twins) develop from a single fertilized egg that splits into two genetically identical replicas, each of which becomes a person.
Fraternal twins (dizygotic twins) develop from separate eggs and separate sperm, making them genetically no more similar than ordinary siblings.
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34. Issues with Twin Studies
By comparing groups of identical and fraternal twins, behavior 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.
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35. Adoption Studies
Investigators seek to discover whether, in behavior 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.
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36. Molecular Genetics
There is now 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.
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37. 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 the organism
The human genome consists of tightly coiled threads of DNA
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38. The Human Genome Project
Began in the 1970s
In the process of mapping the human genome
Has located the genes for Huntington disease, some forms of cancer, and many others
May possibly be used to transplant healthy copies of missing/defective genes into affected cells
May lead to the development of drugs that will alter the genetic makeup of the affected cells
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39. Chromosome and Gene-Linked Abnormalities
Chromosome Abnormalities
Down Syndrome
Klinefelter Syndrome
Fragile X Syndrome
Turner Syndrome
XYY Syndrome
Gene-Linked Abnormalities
Phenylketonuria
Sickle-Cell Anemia
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40. 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
retardation of motor and mental abilities
Women younger than 18 and older than 38 are more likely to have Down syndrome babies.
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41. Klinefelter Syndrome Sex-linked chromosome abnormality
Males have an extra X chromosome, making them XXY instead of XY
Characterized by:
undeveloped testes
enlarged breasts
become quite tall
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42. Fragile X Syndrome Sex-linked chromosome abnormality
The X chromosome becomes constricted and often breaks
Characterized by:
mental deficiency (varied in form from mental retardation to short attention span)
Occurs more frequently in males
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43. 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
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44. XYY Syndrome Sex-chromosome linked abnormality
The male 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.
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45. Phenylketonuria 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.
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46. 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 of the individual
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47. Other Genetic Abnormalities
Cystic Fibrosis
Diabetes
Hemophilia
Huntington Disease
Spina Bifida
Tay-Sachs Disease
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49. Prenatal Diagnostic Tests
Amniocentesis
Ultrasound Sonography
Chorionic Villi Sampling
Maternal Blood Test
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50. 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 )
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51. 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 as microencephaly
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52. Chorionic Villi Sampling
A prenatal medical procedure in which a small sample of the placenta is removed
Performed between the 8th and 11th weeks of pregnancy
Provides information about the presence of birth defects
Has a slightly higher risk of miscarriage than amniocentesis
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53. Maternal Blood Test 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
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54. Infertility
Infertility is the inability to conceive a child after 12 months of regular intercourse
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55. Causes of Infertility Women Men Ovulation problems Low sperm count
Antisperm secretions
Blocked fallopian tubes
Endometriosis
Men
Low sperm count
Immobile sperm
Antibodies against sperm
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56. Infertility Treatment Techniques
In vitro fertilization (IVF) - Egg and sperm are combined in a laboratory dish and resulting fertilized embryo is transferred into the woman’s uterus. (Success rate slightly less than 20%)
Gamete intrafallopian transfer (GIFT) - A doctor inserts eggs and sperm directly into a woman’s fallopian tube. (Success rate almost 30%)
Intrauterine insemination (IUI) - Frozen sperm—of the husband or an unknown donor—is placed directly into the uterus. (Success rate 10%)
Zygote intrafallopian transfer (ZIFT) - Eggs are fertilized in the laboratory then any resulting zygotes are transferred to a fallopian tube. (Success rate approximately 25%)
Intracytoplasmic sperm injection (ICSI) - A single sperm is injected by pipette into an egg and the zygote is returned to the uterus. (Success rate approximately 25%)
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57. Adoption
Adoption is the social and legal process by which a parent-child relationship is established between persons unrelated at birth.
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58. Research Findings on Adoption
Adopted children and adolescents often show more psychological and school-related problems than nonadopted children.
Adopted adolescents are referred to psychological treatment 2-5 times as often as their nonadopted peers.
Early adoption often has better child outcomes than later adoption.
Adoptees show higher levels of prosocial behavior than nonadopted peers.
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59. Adoption Related Issues
Research findings have implications for social policy regarding the foster care system.
Clinical psychologists report that sometimes adoptive parents try to make life too perfect for adoptive children, and thus the children feel that they can’t release any angry feelings or openly discuss problems.
Consensus among psychologists is that adopted children should be told they are adopted.
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61. Intelligence
Arthur Jensen sparked a debate theorizing that intelligence is primarily inherited.
He believed that standardized IQ tests are a good indicator of intelligence.
Jensen supported his theory with findings from twin studies:
IQs of identical twins yielded an average correlation of .82
IQs of ordinary siblings yielded an average correlation of .50
IQs of identical twins reared together yielded a correlation of .89
IQs of identical twins reared apart yielded a correlation of .78
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62. Criticisms of Jensen’s Work
IQ tests tap only a narrow range of intelligence, excluding important aspects such as everyday problem solving, work, and social adaptability.
Most investigations of heredity and environment don’t include environments that differ radically.
Developmentalists believe intelligence is influenced by heredity, but such a strong relationship has not been found.
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63. The Bell Curve: Intelligence and Class Structure in Modern Life
Highly controversial book written in 1994 by Richard Herrnstein and Charles Murray.
States IQ test scores vary across ethnic groups:
Asian Americans score several points higher than Whites.
African Americans score about 15 points lower than Whites.
IQ differences are partly due to heredity.
Believes government funding for projects such as Head Start is wasted.
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64. Criticisms of The Bell Curve
While experts agree that African Americans tend to score lower on IQ tests, they question the ability of the tests to accurately measure intelligence.
The U.S. Supreme Court endorsed this criticism by ruling that tests of general intelligence are discriminatory and cannot be used for determining employment.
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65. Heredity-Environment Correlations
Relates to the concept that individuals’ genes influence the types of environments to which they are exposed.
Behavior-geneticist Sandra Scarr described three ways that heredity and environment are correlated:
Passively
Evocatively
Actively
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66. Passive Genotype-Environment Correlations
Occur when biological parents, who are genetically related to the child, provide a rearing environment for the child.
Example:
Parents who have a genetic predisposition to be intelligent and read skillfully, provide their children with books to read. The children, in turn, become skilled readers due to both their inherited predispositions and environmental influences.
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67. Evocative Genotype-Environment Correlations
Occur because a child’s genotype elicits certain types of physical and social environments.
Examples:
Active, smiling children receive more social stimulation than passive, quiet children do.
Athletically inclined youth tend to elicit encouragement to engage in school sports.
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68. Active (Niche-Picking) Genotype-Environment Correlations
Occur when children and adolescents seek out environments they find compatible and stimulating.
Niche-picking refers to finding a setting that is suited to one’s abilities.
Active selection of environments is related to one’s genotype.
Example:
Teens who are musically inclined select musical environments in which they can successfully perform their skills.
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69. Shared and Nonshared Environmental Experiences
Even though children live under the same roof with the same parents, often their personalities are very different.
Robert Plomin found that common rearing, or shared environment, accounts for little of the variation in children’s personality or interests.
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70. Shared Environmental Experiences
Children’s common experiences such as:
their parents’ personalities and intellectual orientation
the family’s social class
the neighborhood in which they live
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71. Nonshared Environmental Experiences
Children’s unique experiences, both within the family and outside the family, that are not shared with another sibling.
Experiences occurring within the family can be part of the “nonshared environment.”
Parents often interact differently with each sibling, and siblings interact differently with parents.
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72. Conclusions about Heredity-Environment Interaction
Both genes and environment are necessary for a person to exist.
Heredity and environment operate together, or cooperate, to produce:
intelligence weight
temperament ability to pitch a baseball
height ability to read
The emerging view is that genes give people a propensity for a particular developmental trajectory that is ultimately realized through environmental circumstances.
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