Chapter 2: Independent Questions
I. Biological and Evolutionary Theories
1. Summarize the two introductory paragraphs of this section.
Development has many theories that help to explain it. These theories are used to form
hypotheses to try and prove or disprove these theories. There are five different families of
theories that have different ways of answering questions of development. There are also three
families of psychology theories which explain developmental changes.
2. Define the following terms related to genetics:
(a) Chromosomes: strings of genetic material in the nuclei of cells
(b) DNA: a chemical material that makes up chromosomes and genes
(c) Genes: complex chemical units of a chromosome that control or influence traits
(d) Genome: all the DNA that an organism possesses
B. Genotypes, Phenotypes, and Patterns of Inheritance
i. Dominant and Recessive Genes - Optional reading: Not on the exams
ii. Polygenic and Multifactorial Inheritance
3. Heredity is the passing of traits to offspring (from parents or ancestors). There are many different
patterns or rules of heredity/inheritance. Some inherited traits are referred to as Mendelian traits (that is,
traits that are under the direct control of a single gene). Predicting the expression of traits determined by
a single gene (Mendelian traits/monogenic inheritance) is relatively straightforward. However, unlike
monogenic inheritance, polygenetic and multifactorial inheritances are complex.
(a) What does polygenetic inheritance mean?
- a pattern of inheritance in which many genes influence a trait
(b) What does multifactorial inheritance mean?
- a pattern of inheritance affected by both genes and the environment
Some of the traits we inherit cannot be explained by our genes/genome. Epigenetics is a recent theory that
suggests heritability can be operating above the genetic level (i.e., the level of analysis that genetic
theories have traditionally focused exclusively on).
4. Define the following terms:
(a) Epigenome: the sum total of inherited and acquired molecular modifications to the genome
that leads to changes in gene regulation without changing the DNA sequence of the genome
(b) Gene expression: when a gene sequence is activated (“turned on”) and ready to be translated
in gene products- proteins for the most part
(c) Gene silencing: when a gene sequence is made inactive (“turned off”) and is prevented from
being translated into gene products- proteins for the most part
5. Summarize the research findings from the field of Epigenetics presented in the third and fourth paragraphs of this section on “Epigenetics” (pp. 27- 28).
- Epigenetic factors play a large role in development across the lifespan. Experiments on rats
show that maternal care can physically alter molecular epigenetic factors in offspring. This was
shown when an increased level of postnatal feeding and grooming led to calmer rat pups by
altering their molecular epigenetic structures. These changes can persist into adulthood although
through experiments, they can be reversed. Some epigenetic material is hereditary.
6. Read the Research Report on p. 59 in Chapter 3 entitled Twins in Genetic and Epigenetic Research.
a) What is the logic behind comparing identical and fraternal twins to assess the heritability of
traits? (See first and second paragraphs)
- If identical twins who are raised apart show greater similarity then fraternal twins who are
raised together, this shows that heredity plays a large role in the trait being studied. Intelligence tests
given to identical twins raised together, identical twins raised apart, fraternal twins raised together
and non-twin siblings raised apart show that there is strong evidence showing that intelligence may
be a hereditary trait.
b) The report states, “If intelligence and attitudes were determined solely by heredity, identical twins
would be exactly alike, and researchers would find correlations of +1.00” (fourth paragraph).
However, because the correlations found are less than +1.00, environmental factors must also
contribute to intelligence and attitudes. Summarize the key findings from the fifth and six
paragraphs of this research report.
- There is strong evidence to support the idea that genetics are not the sole factor in a person’s
phenotype and that the environment and epigenetics have a large impact as well. Studies looking at
monozygotic twins showed that throughout their lifetimes, the twins went from indistinguishable
epigenetic patterns and phenotypic characteristics as infants to having very different epigenetic
patterns and phenotypic characteristics as an adult, showing that their different experiences had an
influence on their phenotypes and epigenetic patterns.
D. Evolutionary Theories
7. Describe this theoretical view and identify the example provided.
- Nativism is the view that humans possess unique traits that will be manifested in all members of the
species regardless of differences in their environments.
- An example to support this is that all healthy children lean language early in life and so far scientists
have found no evidence to show grammatical language in non-human species.
8. Describe this theoretical view and identify the examples provided.
- Ethology emphasizes genetically determined survival behaviors that are assumed to have evolved
through natural selection.
- An example to support this is the fact that nests are necessary for the survival of young birds.
- Another example is that babies are genetically programmed to cry and the caregiver is genetically
programmed to be irritated by the noise and therefore soothe the child creating an emotional bond. The
genes for crying increase the infant’s chance of survival. iii. Behaviour Genetics
9. Describe this theoretical view and identify the examples provided.
- Behavior genetics is the study of the role of heredity in individual differences
- An example of this is the fact that traits or behaviors are believed to be influenced by genes when
those of related people are more similar to those of unrelated people. Heredity affects behaviors such
as shyness and aggressiveness.
10.Describe this theoretical view and identify the examples provided.
- Sociobiology is the study of society using methods and concepts of biological science. Individual
humans have the best chance for survival when they live in groups, therefore evolution has provided
humans with genetic programming that help us cooperate.
- An example of this is that every society has laws against murder. Sociobiologists believe that humans
are genetically programmed to create rules based on respect for other people’s lives.
v. Evolutionary Psychology - Optional reading: Not on the exams
vi. Evolutionary Developmental Psychology - Optional reading: Not on the exams
vii. Evolutionary Prenatal Programming and Adult Health and Disease - Optional reading: Not on the exams
E. Evaluation of Biological and Evolutionary Theories
i. Disease Control
11.Summarize all the text in this section.
- Advances in human genomics will likely play a role in predicting and preventing diseases in the 21 st
century. The greatest impact of advances in human genomics will likely be seen in the treatment of
multifactorial diseases such as heart disease and cancer. Scientists have begun decoding the genomes
and epigenomes of cancer samples with the aim of developing new strategies for early detection and
prevention. Learning more about epigenetics may help to discover more about how nurture interacts
ii. Early Intervention
12.Summarize all the text in this section.
- Research and evolutionary theory on early-life events are helping scientists make more accurate
predictive-adaptive responses that match future environments. There has been a growing awareness on
the need to promote early interventional strategies during prenatal development (ex. Good
health/nutrition in women of reproductive age). This will help to prevent chronic disease in future
iii. Remaining Questions
13.Summarize all the text in this section. - Critics of evolutionary theories claim that too much emphasis is placed on heredity and not enough
on environmental factors. For example, when the rules of a society no longer work, we invent new
ones which are passed down through the generations through language and not through genes.
- These theories are difficult to prove. How can you test that infants attach to caregivers because
attachment has survival value that has evolved over time?
- Specific cognitive strategies and social behaviors, while there is a strong biological basis, can still be
modified over time.
II. Psychoanalytic Theories
A. Freud’s Psychosexual Theory - Optional reading: Not on the exams
B. Erikson’s Psychosocial Theory - Optional reading: Not on the exams
C. Evaluation of Psychoanalytic Theories - Optional reading: Not on the exams
D. The Humanistic Alternative
14.Summarize the key points presented in the introductory paragraph about the general nature of
- Some psychologists take issue with the psychoanalytic emphasis on atypical development and have
proposed theories that focus on positive aspects of development such as the notion of innate
goodness (J.J. Rousseau) Internal drive is motivation achieve o