Unit 3: Genetics & Evolutionary Foundations Of Behaviour (Chapter 3)

Question 1

Nature

Answer 1

The result of our genetic makeup.

Question 2

Nurture

Answer 2

The environment and experiences that shape us.

Question 3

Genome

Answer 3

Complete set of genetic material; the “blueprint” for making & maintaining an organism.

Question 4

DNA

Answer 4

Molecule that carries genetic information, organized and packaged within chromosomes.
- Most human body cells carry 2 pairs of 23 chromosomes (46 total).
- Exception: reproductive cells, which carry 23.

Question 5

Gene

Answer 5

Segment of DNA that codes for a particular protein. Humans have 2 versions (alleles) of each gene, 1 from each parent.

Question 6

Genotype

Answer 6

Made up of 2 alleles for a particular gene. An individual may be homozygous for gene (NN or nn) or heterozygous for gene (Nn).

Question 7

Phenotype

Answer 7

Observable characteristics of an individual, produced by interaction of genotype and environment.

Question 8

Recessive alleles

Answer 8

Determine phenotype only when individual is homozygous for gene.

Not all genes act in dominant/recessive fashion

Question 9

Dominant alleles

Answer 9

Determines phenotype regardless of whether an individual is homozygous or heterozygous for gene.

Not all genes act in dominant/recessive fashion

Question 10

What do genes code for?

Answer 10

Genes code for proteins, which contribute to phsycial structures & fuctons of the body, including the brain. Multiple genes are involved in giving rise to complex mental states, behaviours, and traits.

Ex: Code proteins and enzymes involved in production of chemical “messengers” and their receptors that allow neurons to “talk” to each other.

Question 11

Behavioural genetics

Answer 11

Establishing the degree of heritability for a trait. (I.e. How much variability for a trait can be attributed to genes.)

Question 12

Evolutionary psychology

Answer 12

Examining why certain genetically-encoded behaviours & traits emerged.

Question 13

Candidate gene studies

Answer 13

Compare individuals with the candidate gene with individuals without on a given trait or disorder.

Question 14

Limitations of candidate gene studies

Answer 14

• Typically correlational in nature (other factors, like other genes, cannot be ruled out).
• Underestimate biological complexity of multifaceted traits & behaviours.
• Many promising candidate gene studies have failed to replicate.

Question 15

Gene knockout

Answer 15

Remove or deactivate gene; modify it so it no longer produces its typical proteins.

Question 16

Gene knockdown

Answer 16

Make gene less active; “turn down” its volume.

Ex: Mice who don’t miss mom study; genetic knockdown of the u-opioid receptor = defecits in attatchment.

Question 17

Genome-wide association studies (GWAS)

Answer 17

Instead of looking at single gene (or small set of genes), scan entire genome & look for associations with particular phenotype. This may allow us to identify variants missed through candidate gene approaches.

Question 18

GWAS Limitations

Answer 18

• Run the rish of false positives,
• Biological relevance often not clear.
• Correlational.

Question 19

How do genes shape our environments?

Answer 19

Genes shape behavioural tendencies & preferences, and thus environments individuals seek out.

Ex: Individuals genetically predisposed to anxiety may seek less stressful professions.

Question 20

Environments moderate the impact of genes

Answer 20

The effect of a gene on the manifestation of a particular phenotype may depend on context. In statistical terms, context moderates impact of gene (can also say that genes and environments interact to produce outcomes). Not all genes read all the time, and environment affects which ones are turned “on” and “off”. Our genome is a blueprint for many potential biological selves.

Ex: Twin studies; chronic social isolation study (both regarding expression of genes).

Question 21

Diathesis-Stress Model

Answer 21

Some individuals have a predisposition (diathesis) that makes them more vulnerable to negative environmental influences (e.g., stress).

Question 22

Differential Susceptibility Model

Answer 22

Some individuals are more sensitive to both negative and positive environmental influences.

Ex: Maternal care as a newborn vs. child outcomes.

Question 23

Epigenetic change

Answer 23

A type of change to structure of DNA that affects gene expression without altering the underlying DNA sequence. I.e. Factors that affect whether a gene is “read” or not. Is reversible, but can have long lasting effects.

Ex: Rat moms with high or low LG.

Question 24

Methylation

Answer 24

Process by which a methyl group attaches to some of the parts in DNA. Influences the production of a gene’s specific protein; mehtylated genes are generally “shut off”.

Question 25

Behavioural genetics

Answer 25

Study of strength of genetic influences on a behaviour/trait/disorder.

Question 26

Heritability

Answer 26

How much of variation in phenotype across people can be attributed to
variation in genotype. Applies to populations, not individuals. Calculated as a proportion ranging from 0 to 1
- 0: Genes do not contribute to how people differ
- 1: Only genetic factors are responsible for differences.
**Typical range of a trait is between .3 and .6 (30% - 60%)

Ex: With identical twins, one can examine variation in genes while holding environment constant, or vice-versa.

Question 27

Identical/monozygotic twins

Answer 27

Share 100% of their DNA. Develop from the division of a single fertilized egg.

Question 28

Fraternal/dizygotic twins

Answer 28

Share 50% of their DNA. Develop from two seperate eggs.

Question 29

Evolution

Answer 29

Change in species over time; descent with modification from a common ancestor.

Question 30

Artificial selection

Answer 30

Human-controlled selective breeding.

Question 31

Natural selection

Answer 31

Process through which certain traits become more or less common in a population over time due to pressures of the environment.
Three key components:
1. Variation
2. Heredity
3. Differential fitness

Question 32

Variation

Answer 32

Within a population of organisms, there is variation in traits or characteristics.

Question 33

Heredity

Answer 33

Some of this variation is passed down from parents to offspring (we know know this is through genetic inheritance). Either through the reshuffling of genes during sexual reproduction on mutations.

Question 34

Mutations

Answer 34

Errors during DNA replication.

Question 35

Differential fitness

Answer 35

Not all individuals in a population survive and reproduce equally.

Question 36

Adaptations

Answer 36

Favourable traits better suited to the environment that increase chances of survival & reproduction. These favourable traits gradually accumulate over generations.

Question 37

Fitness

Answer 37

Interaction between characteristics & prevailing environment.

Question 38

Functionalist approach in psychology (Functionalism)

Answer 38

Explains behavioural / mental / emotional / physiological processes by their utility.

Ex: Why do we help others? Why do men tend to be more aggressive than women?

Question 39

Distal explanations of behaviour

Answer 39

What role did behaviour play in survival and reproduction over evolutionary time?

Ex: Male songbirds sing in the spring to attract females & warn other males to stay away.

Question 40

Proximate explanations of behaviour

Answer 40

Immediate triggers of the behaviour.

Ex: Increased daylight in the spring triggers testosterone production which acts on brain regions responsible for singing.

Question 41

Genes

Answer 41

The basic physical and functional units of heredity; made up of DNA.

Question 42

If you assume there has been an adaptation you should…

Answer 42

See some evidence of univerality around the world, across different cultures, people.

Question 43

Neuroscience

Answer 43

The study of how nerves and cells send and recieve information from the brain, body and spinal cord.

Question 44

Neurodiversity

Answer 44

The appreciation of the inherent differences among individuals in how their brains function.

Question 45

Genotype

Answer 45

The genetic makeup of an organism composed of the organism’s complete set of genes.

Question 46

Allele

Answer 46

A variant form of a gene; humans have two alleles per gene, one inherited from each parent. Alleles influence a phenotype by having a strong (dominant) or weak (recessive) influence.

Question 47

Gene expression

Answer 47

The turning on and off of genes in a particular cell to determine how that cell functions.

Question 48

Epigenics

Answer 48

The study of how the interactions between your genes and the environment regulate your gene expression through chromosomal modifications and chemical modification of DNA bases.

Question 49

Behavioural genetics

Answer 49

The study of how genetic factors influence trait variation (a difference in characteristics) between individuals, whether that trait is visible (ex: hieght) or more abstract, but still measurable (ex: emotional instability).

Question 50

Heritability

Answer 50

An indication of how much variation in phenotype across people is due to differences in genotype.

Question 51

Chromosome

Answer 51

A threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.

Question 52

Limitations to twin studies

Answer 52

• Equal environment assumption in MZ vs DZ twin studies:
  But MZ twins may be treated more similarly -> inflated heritability estimates.
• Selective placement in MZ twin adoption studies leads to more similar environments.
• Complex gene x environment interactions.
  MZ twins may create more similar environments.
  Environmental influences on gene expression, epigenetic processes, etc.

Question 53

The need to belong and the reason for why it emerged

Answer 53

Human beings have a fundamental need to form and maintain at least a minimum quantity of lasting, positive, and significant interpersonal relationships.
- Tendency to affiliate with others (and avoid exclusion) is an adaptation.
- Throughout our evolutionary history, group living served as multi-purpose survival tool:
Help hunting large game & foraging;
Sharing food;
Defensive vigilance and greater strength against predators and hostile outgroups;
Help caring for offspring;
Access to mates.