Download chapter 3: biological beginnings

CHAPTER 3: BIOLOGICAL
BEGINNINGS
THE EVEOLUTIONARY
PERSPECTIVE
Natural Selection and Adaptive
Behavior
Natural Selection – The evolutionary process that favors
individuals of a species that are best adapted to survive and
reproduce – Darwin’s On the Origin of Species.
Adaptive Behavior – That which promotes an organism’s
survival in its habitat (e.g, eagle’s claws), attachment in
humans.
Evolutionary psychology – Emphasis on the importance of
adaptation, reproduction, and survival of the fittest in
explaining behavior. Evolution favors behaviors that promote
survival.
GENETIC FOUNDATIONS :
What are Genes?
Chromosomes – Threadlike structures of 23 pairs,
one member of each pair from each parent,
containing DNA. Each gene is a short segment
composed of DNA acting as a blueprint for cells to
reproduce themselves.
Mitosis is the process where each chromosome in
the cell’s nucleus duplicates itself. Meiosis is
where each pair of chromosomes separates – one
member going to each gamete.
Genetic Principles
Dominant-recessive genes principle – The explanation of
gene dominance relative to hair color, eyesight, and
freckles.
Sex-linked genes – An explanation of the XY
chromosomal makeup that determines gender.
Genetic imprinting – The dominance of imprinted genes
and its effect on some genetic diseases.
Polygenic inheritance – The interaction of genes, forming
the organism’s genotype and phenotype.
Reaction range – Demonstrates the importance of an
environment’s positive and negative effects.
Canalization – Nature’s pathway to development thought
to be a protective measure from environmental extremes.
Methods Used by Behavior Genetics –
genetic influence on behavior.
Identical twins – monozygotic – single fertilized egg
Fraternal twins – dizygotic – separate eggs
Twin studies help establish heredity’s effect on behavior.
Adoption studies reveal more strength for the inheritedbehavior theory.
Molecular genetics – and the categorization of the human
gene through the Genome Project. There is great potential
here for the control of some diseases.
Chromosome and Gene-Linked
Abnormalities
Down syndrome – The presence of a 47th chromosome, leading to a
child with specific physical characteristics and mental limitations.
Klinefelter syndrome – A sex-linked abnormality found in males who
have an extra X chromosome affecting sexual traits.
Fragile X syndrome – An abnormality in the X chromosome, causing
mental retardation and learning disabilities.
Turner syndrome – Females missing an X chromosome, leading to
possible infertility and some learning disabilities.
XYY syndrome – An extra Y chromosome in males, causing aboveaverage height.
Phenylketonuria – Organism cannot metabolize an amino acid – could
cause mental retardation and hyperactivity.
Sickle-cell anemia – Most often found in African Americans, affecting
red blood cells, causing anemia and possibly early death.
Reproductive Challenges and
Choices
Amniocentesis – A test by which amniotic fluid is withdrawn and
tested for chromosomal or metabolic disorders.
Ultrasound sonography – Soundwaves that are transformed into
visual representations of the fetus.
Chorionic villi sampling – Where a sample of the placenta is removed
and tested for birth defects; considered to be more dangerous than
amniocentesis.
Maternal blood test – Used to assess blood alpha protein level to
identify possible defects to the brain and spinal cord formation.
Infertility – Occurring in approximately 10 to 15 percent of couples in
the United States who cannot conceive a child through regular
intercourse. Causes and results are studied.
Adoption – The effects of adoption on children and the challenges to
adoptive parents are discussed.
HEREDITY-ENVIRONMENT INTERACTION
Intelligence – What is the heredity and environmental
influence on intelligence?
Jensen contended that environment is minimal to
heredity – a view that sparked controversy.
The Bell Curve – A book by Herrrnstein and Murray
(1994) statistically supporting Jensen’s contention also
provided controversy. The argument centers on the belief
that IQ can or cannot be quantified.
Environment – Scientists believe that rich environments can
raise intelligence, as is evidence by some studies that focused on
children born of low socioeconomic status parents and raised in
high socioeconomic status environments.
HEREDITY-ENVIRONMENT CORRELATIOINS
Passive genotype-environment correlations –Biological parents
provide rearing environment for child.
Evocative genotype-environment correlations – Genetic foundation s
elicit social and physical influences from the environment. (Agreeable
children get more positive attention.)
Active (niche-picking) genotype-environment correlations – seeking
environments that are found compatible to the individual.
Shared and nonshared environmental experiences – Children’s
common genetic inheritances versus their unique experiences in and
outside the family.
Conclusions about heredity-environment interaction – Heredity and
environment operate together. Both environment and heredity are
complex in their own way and both are influenced by the other.