Biological
Beginnings
Chapter 2
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Chapter Outline
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The evolutionary perspective
Genetic foundations of development
Reproductive challenges and choices
Heredity-environment interaction: The naturenurture debate
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The Evolutionary Perspective
• Natural selection and adaptive behavior
• Evolutionary psychology
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Natural Selection and Adaptive
Behavior
• Natural selection - Evolutionary process by
which those individuals of a species that are
best adapted are the ones that survive and
reproduce
• Adaptive behavior - Promotes an organism’s
survival in the natural habitat
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Evolutionary Psychology
• Emphasizes the importance of adaptation,
reproduction, and survival of the fittest in
shaping behavior
• Evolutionary developmental psychology
– Interest has grown in using the concepts of
evolutionary psychology to understand human
development
– Psychological mechanisms are domain-specific
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Evolutionary Psychology
• Connecting evolution and life-span
development
– Benefits conferred by evolutionary selection
decrease with age
– Natural selection primarily operates during the
first half of life
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Evolutionary Psychology
– Older adults
• Weaken biologically
• Need culture-based resources
– Cognitive skills, literacy, medical technology, and social
support
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Figure 2.2 - Baltes’ View of Evolution and
Culture Across the Life Span
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Evolutionary Psychology
• Evaluation
– Evolution gave us biological potentialities but it
does not dictate behavior
– People have used their biological capacities to
produce diverse cultures
• Aggressive and peace-loving, egalitarian and autocratic
– Studying specific genes in humans and other
species and their links to traits and behaviors
• Best approach for testing ideas coming out of
evolutionary psychology
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Genetic Foundations of Development
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The collaborative gene
Genes and chromosomes
Genetic principles
Chromosomal and gene-linked abnormalities
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The Collaborative Gene
• Human life begins as a single cell
• Nucleus of each cell contains chromosomes
– Chromosomes: Threadlike structures made up of
deoxyribonucleic acid
– DNA: A complex double-helix molecule that
contains genetic information
• Genes: Units of hereditary information, are
short segments of DNA
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Figure 2.3 - Cells, Chromosomes, DNA,
and Genes
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
The Collaborative Gene
• Genome-wide association method - Identify
genetic variations linked to a particular
disease
• Human genome consists of many genes that
collaborate:
– Both with each other and with nongenetic factors
inside and outside the body
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
The Collaborative Gene
• Activity of genes is affected by their
environment
• Stress, radiation, and temperature can
influence gene expression
• Exposure to radiation changed the rate of DNA
synthesis in cells
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Genes and Chromosomes
• Mitosis, meiosis, and fertilization
– Mitosis: Reproduction of cells
– Meiosis: Cell division that forms sperm and eggs
(gametes)
– Fertilization: A stage in reproduction when an egg
and a sperm fuse to create a single cell, called a
zygote
• Zygote: A single cell formed through fertilization
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Figure 2.5 - The Genetic Difference
Between Males and Females
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Genes and Chromosomes
• Sources of variability
– Combining the genes of two parents in off spring
increases genetic variability
– Identical twins (monozygotic twins)
• Develop from a single zygote that splits into two
genetically identical replicas, each of which becomes a
person
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Genes and Chromosomes
– Fraternal twins (dizygotic twins)
• Develop when two eggs are fertilized by different
sperm, creating two zygotes that are genetically no
more similar than ordinary siblings
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Genes and Chromosomes
– Mutated gene - Permanently altered segment of
DNA
– Susceptibility genes - Make the individual more
vulnerable to specific diseases or accelerated
aging
– Longevity genes - Make the individual less
vulnerable to certain diseases and more likely to
live to an older age
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Genes and Chromosomes
– Genotype: Genetic heritage
– Phenotype: Way an individual’s genotype is
expressed in observed and measurable
characteristics
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Genetic Principles
• Dominant-recessive genes principle
– One gene of a pair always exerts its effects
(dominant), overriding the potential influence of
the other gene (recessive)
• Sex-linked genes
– When a mutated gene is carried on the X
chromosome, the result is called X-linked
inheritance
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Genetic Principles
• Genetic imprinting
– Occurs when the expression of a gene has
different effects depending on whether the
mother or the father passed on the gene
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Genetic Principles
• Polygenic inheritance
– Polygenically determined - Determined by the
interaction of many different genes
– Gene-gene interaction - Studies that focus on the
interdependence of two or more genes in:
• Influencing characteristics, behavior, diseases, and
development
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Figure 2.6 - Some Chromosomal
Abnormalities
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Gene-Linked Abnormalities
• Phenylketonuria (PKU)
– Metabolic disorder that, left untreated, causes
mental retardation
• Sickle-cell anemia
– Blood disorder that limits the body’s oxygen
supply
– Can cause joint swelling, as well as heart and
kidney failure
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Gene-Linked Abnormalities
• Cystic fibrosis
– Glandular dysfunction that interferes with mucus
production
– Breathing and digestion are hampered, resulting
in a shortened life span
• Diabetes
– Body does not produce enough insulin, which
causes abnormal metabolism of sugar
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Gene-Linked Abnormalities
• Hemophilia
– Delayed blood clotting causes internal and
external bleeding
• Huntington’s disease
– Central nervous system deteriorates, producing
problems in muscle coordination and mental
deterioration
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Gene-Linked Abnormalities
• Spina bifida
– Neural tube disorder that causes brain and spine
abnormalities
• Tay-Sachs disease
– Deceleration of mental and physical development
caused by an accumulation of lipids in the nervous
system
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Dealing with Genetic Abnormalities
• Every individual carries DNA variations that
might predispose the person to serious
physical disease or mental disorder
• Genes that are missing, nonfunctional, or
mutated can be associated with disorders
• Knowledge of genetic flaws might bring
important costs as well as benefits
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Reproductive Challenges and Choices
• Prenatal diagnostic tests
• Infertility and reproductive technology
• Adoption
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Prenatal Diagnostic Tests
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Ultrasound sonography
Brain imaging techniques
Chorionic villus sampling
Amniocentesis
Maternal blood screening
Noninvasive prenatal diagnosis (NIPD)
Fetal sex determination
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Infertility and Reproductive
Technology
• Infertility - Inability to conceive a child after
12 months of regular intercourse without
contraception
• In vitro fertilization (IVF) - Eggs and sperm are
combined in a laboratory dish
– Fertilized egg is transferred into the woman’s
uterus
• Success rate of IVF depends on the mother’s
age
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Adoption
• Social and legal process that establishes
parent-child relationship between persons
unrelated at birth
– Increased diversity of adopted children and
adoptive parents
– Outcomes for adopted children
• Adopted children fare much better than children raised
in long-term foster care
• Children who are adopted very early are more likely to
have positive outcomes
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Heredity-Environment Interaction:
The Nature-Nurture Debate
• Behavior genetics
• Heredity-environment correlations
• Shared and nonshared environmental
experiences
• The epigenetic view and gene x environment
(g x e) interaction
• Conclusions about heredity-environment
interaction
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Behavior Genetics
• Seeks to discover the influence of heredity
and environment on individual differences in
human traits and development
– Twin study: Behavioral similarity of identical and
fraternal twins is compared
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Behavior Genetics
– Adoption study: Seek to discover whether, in
behavior and psychological characteristics,
adopted children are:
• More like their adoptive parents, who provided a home
environment
• More like their biological parents, who contributed
their heredity
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Figure 2.11 - Exploring HeredityEnvironment Correlations
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Shared and Nonshared Environmental
Experiences
• Shared environmental experiences: Siblings’
common environmental experiences
– Their parents’ personalities and intellectual
orientation
– Family’s socioeconomic status
– Neighborhood in which they live
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Shared and Nonshared Environmental
Experiences
• Nonshared environmental experiences:
Child’s own unique experiences
– Both within the family and outside the family
– Not shared with another sibling
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Epigenetic View and Gene ×
Environment (G × E) Interaction
• Epigenetic view: Development is the result of
an ongoing, bidirectional interchange
between heredity and environment
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Figure 2.12 - Comparison of The Heredity Environment Correlation and Epigenetic Views
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document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
Heredity-Environment Interaction:
The Nature-Nurture Debate
• Gene × environment (G × E) interaction:
Interaction of:
– Specific measured variation in the DNA
– Specific measured aspect of the environment
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