Download Life span chapter 2-1 File

Earliest Development
The Interaction of Heredity and
Environment
Beginning of Life
Gametes from male and female join
– Ovum and sperm
Fused gametes create zygote
At the moment of conception (a), humans receive 23 pairs
of chromosomes (b), half from the mother and half from
the father. These chromosomes contain thousands of
genes, shown in the computer-generated map (c).
The Contents of a Single Human Cell
Genes
– DNA
Chromosomes
– Rod-shaped DNA
portions in 23 pairs
– Contain genetic
blueprint for individuals
– Replicate through
mitosis
And baby makes two or three or more!
Rising Multiples
Multiple births have
increased significantly over
the last 25 years.
What are some of the
reasons for this
phenomenon?
Source: Martin et al. 2010.
What causes multiple births?
•
•
•
•
Fertility drugs
Age of mother
Inherited differences
Racial, ethnic, and national differences
Determining Sex
•
23rd chromosome
determines sex of
child.
• Female: Two
matching X
• Male: XY
•
New techniques help
to identify DNA in
sperm; unwanted sex
chromosomes can be
discarded.
Mixing and Matching of Genes
Just the right type
Genotype
– Homozygous
– Heterozygous
Phenotype
Genetic Information Transmission
Uniquely Human?
• Humans have about
25,000 genes,
making them not
much more
genetically complex
than some primitive
species.
Source: Celera Genomics:
International Human Genome
Sequencing Consortium, 2001.
The Human Genome and Behavioral
Genetics: Cracking the Genetic Code.
• In 2001, molecular geneticists mapped the
sequence of genes on each chromosome.
• Number of human genes revised
downward to 25,000.
• 99.9 percent of gene sequence shared by
all humans.
• Human gene sequence supports field of
behavioral genetics.
In what ways can information from the
Human Genome Project affect your life?
When Development Deviates
Causes
– Genetics
– Spontaneous mutation
– Environmental insult
When Development Deviates
Consequences
Down Syndrome
Fragile X Syndrome
Sickle-cell Anemia
Tay-Sachs Disease
Klinefelter’s Syndrome
Genetic Counseling:
Predicting the Future
From the Genes of the
Present
Genetic counseling
In amniocentesis, a sample
of fetal cells is withdrawn
from the amniotic sac and
used to identify a number
of genetic defects.
•
Focuses on helping
people deal with inherited
disorders issues
•
Uses variety of data:
Physical examination,
karyotype
•
Germ line therapy
Prenatal Testing
Amniocentesis
Sonoembryology
CVS
Embryoscopy
Sonogram
FBS
Ultrasound
sonography
In humans, the male sex cell (sperm) and the
female sex cell (the ovum) provide the developing
baby with 23 chromosomes each.
A recessive gene responsible for a disorder may be
passed on silently, revealing itself only when it is
paired with another recessive gene.
The field of behavioral genetics, a combination of
psychology and genetics, studies the effects of
genetics on behavior.
Sex cells (the ova and the sperm) are different
from other cells because they:
a. have twice the 46 chromosomes necessary so that
when the cells combine and material is “spilled,” the
appropriate number of chromosomes will still be there.
b. each has half of the 46 chromosomes so that when
they combine, the new zygote will have all the genetic
information necessary.
c. are younger than all other cells in the developing
human body.
d. are the only cells with chromosomal information.
According to Mendel, when competing traits are both
present, only one trait, also known as the
______________ trait, can be expressed.
a. homozygous
b. recessive
c. polygenic
d. dominant
Just because a disorder has genetic roots does not
mean that environmental factors do not also play a
role.
• True
• False
How can the study of identical twins who were
separated at birth help researchers determine
the effects of genetic and environmental
factors on human development?
The Interaction of Heredity and Environment
What do you think?
A given behavior is not caused just by
genetic factors, nor is it caused solely by
environmental factors.
Studying Development: How Much Is
Nature? How Much Is Nurture?
Nonhuman animal studies
– Controls genetics and environment
– Offers substantial opportunities, but cannot
guarantee generalization to humans
Human studies
– Includes adoption studies; twin studies; family
studies; non-related people of similar background
studies
– Cannot control genetic background or human
environments
When nurture becomes nature
• Transgenerational epigenetic inheritance:
Individual’s life experiences can be passed
down to children, grandchildren, and
subsequent generations
• Why would the poor life choices we make in our
youth, rather than those we might make later in
life, have possible consequences for our
children?
Do you have your mother’s eyes?
Physical traits: Family resemblances
• More genetic similarity  more likely to
share physical characteristics
Nature, Nurture, and Intelligence
• Relative contributions of nature and nurture
highly researched
• Closer genetic link = greater correspondence of
overall IQ scores
Genetics and IQ
Do we inherit our personality?
A link look
Two of the “Big Five”
personality traits linked
to genetic factors
– Neuroticism
– Extroversion
Less basic personality
traits also linked
– Political attitudes
– Religious interests and
values
– Attitudes toward human
sexuality
Are some children born to be
outgoing and extroverted?
The answer seems o be “yes.”
What evidence supports this claim?
What about environmental influences?
Culture
Parental
encouragement
Cultural
Dimensions
Can a culture’s
philosophical outlook
be determined by
genetics?
Religion may help mold
temperament;
temperament may make
certain religious ideals
more attractive.
Psychological Disorders: The Role of
Genetics and Environment
Several psychological disorders are related, at
least in part, to genetic factors.
•
•
•
•
•
Schizophrenia
Major depression
Alcoholism
Autism
ADHD
Genetics of Schizophrenia
Psychological Disorders: The Role of
Genetics and Environment
Genetics often produces a tendency toward a
future course of development, but when and
whether the characteristic will be displayed
depends on the environment.
Gene-environmental Influence
Sandra Scarr suggests three ways a child’s
genetic predisposition may influence his or her
environment.
– Active
– Passive
– Evocative
Fundamental Principle
Within debate about relative influence
of nature and nurture
– Role of genetics is often to produce
tendency toward future course of
development
– Role of environment affects when and
whether a certain behavioral characteristic
will actually be displayed
Using a variety of approaches, developmental
researchers have come to the general conclusion
that virtually all traits, characteristics, and behaviors
result from a combination and interaction of nature
and nurture.
Genetic influences have been identified in physical
characteristics, intelligence, personality traits and
behaviors, and psychological disorders.
There is some speculation that entire cultures may
be predisposed genetically toward certain types of
philosophical viewpoints and attitudes.
Most behavioral traits are a product of genetic
influence and environmental factors. This is also
known as ______________.
a. systematic desensitization
b. creative orientation
c. genetic predetermination
d. multifactorial transmission
Instead of asking if behavior is caused by genetic
or environmental influence, we should be asking
how much of the behavior is caused by genetic
factors and how much is caused by environmental
factors.
• True
• False
According to psychologist Jerome Kagan,
differences in temperament between Chinese and
American children suggest a culture’s philosophical
outlook may be related to ______________ factors.
a. environmental
b. genetic
c. cultural
d. social
Are there personality characteristics that you
believe you inherited from one or both or your
parents?
How might they have been affected by an
environment different from the one you have
experienced?