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3
Biological
Beginnings
John W. Santrock
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Slide 2
Biological Beginnings
• What Is the Evolutionary Perspective?
• What Are the Genetic Foundations of
Development?
• What Are Some Reproductive Challenges and
Choices?
• How Do Heredity and Environment Interact?
The Nature-Nurture Debate
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
What Is the Evolutionary Perspective?
Slide 3
Natural Selection and
Adaptive Behavior
• Stories of the Jim and Jim Twins
– Identical twins separated after birth
– Identical lifestyles after 39 years apart
– Part of Minnesota Study of Twins Reared
Apart; other twin sets with similar
outcomes
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
What Is the Evolutionary Perspective?
Slide 4
Natural Selection and
Adaptive Behavior
• Natural selection: evolutionary
process favors individuals best
adapted to survive and reproduce
• Evolutionary psychology:
emphasizes adaptation, reproduction,
and “survival of the fittest” in shaping
behavior
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
What Is the Evolutionary Perspective?
Slide 5
Evolutionary Developmental
Psychology
• Extended “juvenile” period evolved
• Aspects of childhood prepare for
adulthood
• Some childhood characteristics are
adaptive at specific points in life
• Psychological mechanisms evolved
as domain-specific
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
What Is the Evolutionary Perspective?
Slide 6
Brain Sizes of Humans and
Primates
Fig. 3.1
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
What Is the Evolutionary Perspective?
Slide 7
Evaluating Evolutionary
Psychology
• Evolution gives bodily structures and
biological potentials; does not dictate
behavior
• Biology allows broad range of cultural
possibilities
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
What Are the Genetic Foundations of Development?
Slide 8
The Genetic Process
• DNA and the Collaborative Gene
– Life begins as a single cell; each has
replica of original code
– Chromosomes: threadlike structures
that come in 23 pairs, one member of
each pair coming from each parent
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
What Are the Genetic Foundations of Development?
Slide 9
The Genetic Process
• DNA: The Collaborative Gene
– DNA: complex molecule that
contains genetic information
– Genes: units of hereditary
information composed of DNA;
each has its own function
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Slide 10
Cells, Chromosomes, Genes, and DNA
Cell
Chromosomes
DNA
Nucleus (center
of cell) contains
chromosomes
and genes
Chromosomes are
threadlike structures
composed of DNA
molecules
Gene: a segment of
DNA (spiraled double
chain) containing the
hereditary code
Fig. 3.2
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
What Are the Genetic Foundations of Development?
Slide 11
The Genetic Process
• Human Genome Project
– Humans have about 25,000 genes
– Each gene is dependent, collaborative
• Mitosis, Meiosis, and Fertilization
– Mitosis: cell’s nucleus duplicates itself
– Meiosis: cell division to form eggs and
sperm (or gametes)
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
What Are the Genetic Foundations of Development?
Slide 12
The Genetic Process
• Mitosis, Meiosis, and Fertilization
– Reproduction: begins when female
gamete (ovum) fertilized by male gamete
(sperm)
– Zygote: single cell formed through
fertilization; 23 pairs of chromosomes
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
What Are the Genetic Foundations of Development?
Slide 13
The Genetic Process
• Sources of Variability
– Genotype: genetic heritage
– Phenotype: genotype expressed in
observed and measurable
characteristics
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
What Are the Genetic Foundations of Development?
Slide 14
The Genetic Difference Between
Males and Females
The X and Y
chromosomes
in 23 pairs
including sex
chromosomes
Fig. 3.4
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
What Are the Genetic Foundations of Development?
Slide 15
Genetic Principles
• Dominant-Recessive Genes Principle
– Recessive gene is influential only if both
genes are recessive
• Sex-Liked Genes: X-linked inheritance
• Genetic Imprinting
• Polygenetic Inheritance
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Fig. 3.5
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Genetic Principles
Brown-haired
parents can
have a blondhaired child:
the gene for
blond hair is
recessive
B Brown
hair
b Blond
hair
Father
Bb
B B
Mother
Bb
B b
B b
b b
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
What Are the Genetic Foundations of Development?
Slide 17
Chromosome Abnormalities
• Chromosome abnormalities: gamete
does not have normal set of 23
• Down syndrome: chromosomally
transmitted form of mental retardation
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
What Are the Genetic Foundations of Development?
Slide 18
Sex-Linked Chromosome
Abnormalities
Klinefelter syndrome
Disorder in males; extra
X chromosome
Fragile X syndrome
Abnormality in X chromosome;
becomes constricted or breaks
Turner syndrome
Female disorder; X chromosome
missing partially deleted
XYY syndrome
Disorder in males; extra
Y chromosome
Fig. 3.6
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
What Are the Genetic Foundations of Development?
Slide 19
Gene-Linked Abnormalities
• Phenylketonuria (PKU): individual
cannot properly metabolize an amino
acid; easily detected and prevented
• Sickle-cell anemia: affects red blood
cells; recessive gene influence
• Genetic counselors are available
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
What Are Some Reproductive Challenges and Choices?
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Prenatal Diagnostic Tests
• Ultrasound sonography: high-frequency
sound waves directed into abdomen
• Chorionic villi sampling: sample of the
placenta
• Amniocentesis: sample of amniotic fluid
•
• Maternal blood or triple screening
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
What Are Some Reproductive Challenges and Choices?
Slide 21
Infertility and Reproduction
Technology
• Infertility: inability to conceive after
12 months of regular intercourse
• In vitro fertilization (IVF)
• Gamete intrafallopian transfer (GIFT)
• Zygote intrafallopian transfer (ZIFT)
• Adoption: screened in/out couples
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Success Rates of Three Reproductive Techniques
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50
40
30
31%
29.2%
20
24.5%
10
0
IVF
GIFT
ZIFT
Fig. 3.8
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
What Are Some Reproductive Challenges and Choices?
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Caring for Children
• Effective parenting of adopted children
– Be supportive and caring
– Be involved and monitor the child
– Be a good communicator
– Help the child develop self-control
– Face challenges with a positive approach
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
What Are Some Reproductive Challenges and Choices?
Slide 24
Parenting Adopted Children
Infancy
Early childhood
Middle\late childhood
Develop positive
attachment bond
Family differentiation
Open communications
Adolescence
Provide support
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
How Do Heredity and Environment Interact? The Nature-Nurture Debate
Slide 25
Behavior Genetics
• Behavior genetics: influence of
heredity and environment on individual
trait and developmental differences
– Twin studies: compare behavioral
similarity of identical (monozygotic) twins
with behavioral similarity of fraternal
(dizygotic) twins
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
How Do Heredity and Environment Interact? The Nature-Nurture Debate
Slide 26
Behavior Genetics
• Behavior genetics: influence of
heredity and environment on individuals’
differences
– Adoption studies: discover whether
adopted children are more like adoptive
parents or biological parents
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
How Do Heredity and Environment Interact? The Nature-Nurture Debate
Slide 27
Heredity-Environment
Correlations
• Heredity-environment interaction has
complexities
• Individuals influence environments, yet
individuals “inherit” environments
• The three genotype-environment
correlations change as children grow
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
How Do Heredity and Environment Interact? The Nature-Nurture Debate
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Genotype-Environment
Correlations
Passive
When natural parents
provide rearing
environment
Evocative
When genotype elicits
certain types of physical
and social environments
Active
(niche-picking)
When children seek out
compatible and
stimulating environments
Fig. 3.10
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
How Do Heredity and Environment Interact? The Nature-Nurture Debate
Slide 29
Shared and Nonshared
Environmental Experiences
• Shared environmental experiences:
Siblings’ common experiences
– Parents’ personalities
– Intellectual orientation
– Family’s socioeconomic status
– Neighborhood
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
How Do Heredity and Environment Interact? The Nature-Nurture Debate
Slide 30
Shared and Nonshared
Environmental Experiences
• Nonshared environmental
experiences; the unique child
– Within family
– Outside family
– Not shared by another sibling
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
How Do Heredity and Environment Interact? The Nature-Nurture Debate
Slide 31
The Epigenetic View
• Development is the result of
ongoing, bi-directional interchange
between heredity and environment
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Slide 32
Comparison of the Heredity-Environment
Correlation and Epigenetic Views
Fig. 3.11
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
How Do Heredity and Environment Interact? The Nature-Nurture Debate
Slide 33
Conclusions About HeredityEnvironment Interaction
• Operate cooperatively
• Relative contributions are
not additive
• Many complex behaviors
have some genetic loading
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Slide 34
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The End
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.