Download Section Two - Black Hawk College

Chapter 3
Biological
Beginnings
Biological Beginnings
The Evolutionary
Perspective
Genetic
Foundations
Reproduction
Challenges
and Choices
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HeredityEnvironment
Interaction
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The Evolutionary
Perspective
Natural Selection
and Adaptive
Behavior
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Evolutionary
Psychology
3
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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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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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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•
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
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patterns.
Evolution and LifeSpan 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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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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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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Evaluating
Evolutionary
Psychology
• Albert Bandura
• Steven Jay Gould
• Theodore Dobzhansky
• The Bidirectional View
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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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Steven Jay Gould
• Concluded that in most
domains of human functioning,
biology allows a broad range of
cultural possibilities
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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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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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Genetic
Foundations
What Are
Genes?
Mitosis and
Meiosis
Genetic
Principles
Behavior
Genetics
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Molecular
Genetics
Chromosome
and GeneLinked
Abnormalities
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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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Genetic Building
Blocks
• DNA
• Genes
• Chromosomes
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Definition of DNA
• Deoxyribonucleic acid
is a complex molecule,
shaped like a double
helix, that contains
genetic information.
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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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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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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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The Difference
Between Mitosis and
Meiosis
• Mitosis
– Focus is on cell
growth and repair
– The number of
chromosomes
present remains the
same (the
chromosomes copy
themselves)
– Two daughter cells
are formed
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• Meiosis
– Involves sexual
reproduction
– The
chromosomes
are halved
– Four daughter
cells are
produced
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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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Genetic Principles
• Dominant-recessive genes
principle
• Sex-linked genes
• Polygenically inherited
characteristics
• Reaction range
• Canalization
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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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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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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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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
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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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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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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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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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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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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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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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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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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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Chromosome and
Gene-Linked
Abnormalities
• Chromosome
Abnormalities
– Down Syndrome
– Klinefelter
Syndrome
– Fragile X Syndrome
– Turner Syndrome
– XYY Syndrome
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• Gene-Linked
Abnormalities
– Phenylketonu
ria
– Sickle-Cell
Anemia
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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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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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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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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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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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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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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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•
•
•
•
•
•
Other Genetic
Abnormalities
Cystic Fibrosis
Diabetes
Hemophilia
Huntington Disease
Spina Bifida
Tay-Sachs Disease
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Reproduction Challenges
and Choices
Prenatal
Diagnostic
Tests
Infertility
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Adoption
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Prenatal Diagnostic
Tests
•
•
•
•
Amniocentesis
Ultrasound Sonography
Chorionic Villi Sampling
Maternal Blood Test
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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)
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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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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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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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Infertility
• Infertility is the
inability to conceive a
child after 12 months
of regular intercourse
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Causes of Infertility
• Women
• Men
– Ovulation
problems
– Antisperm
secretions
– Blocked
fallopian tubes
– Endometriosis
– Low sperm
count
– Immobile
sperm
– Antibodies
against sperm
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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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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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Research Findings on
Adoption
• Adopted children and adolescents often
show more psychological and schoolrelated 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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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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Heredity - Environment
Interaction
Intelligence
Heredity-Environment Shared and Nonshared Conclusions about
Correlations
Environmental Heredity-Environment
Influences
Interaction
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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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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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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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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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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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Passive GenotypeEnvironment 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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Evocative GenotypeEnvironment 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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Active (Niche-Picking) GenotypeEnvironment 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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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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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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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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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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