Genes and behaviour Flashcards
genetics and behaviour debates
Free-will vs determinism
Reductionism vs holism
genetic arguments of behaviours
- Based on the principle inheritance
- Genes and their DNA passed down from parents to their offspring - 50% from each parent
- Humans have 23 pairs of chromosomes - approx 20,000 - 25, 000 genes
- Some genes identified for medical conditions
E.g. Mutation in the BRCA1 and BRCA2
gene
a unit or heredity, a region of DNA that encodes a specific trait or function
genome
Refers to all the genes an individual possesses
genotype
set of traits coded in individuals DNA
phenotype
The characteristics manifested in an individuals appearance, characteristics or behaviour.
Can be observable (e.g. eye colour) or unobservable (eg: blood type)
alleles
Different forms of the gene: can be dominate or recessive
recessive alleles
Trait controlled by the recessive allele only develops if allele is present in BOTH chromosome pairs
dominant allele
If trait is controlled by a dominant allele, only has to be present in ONE of the chromosomes in the pair
behavioural genetics
Even if an individual has a genetic predisposition towards a certain behaviour, without the appropriate environmental stimuli, the gene is not “turned on” and the behaviour is not expressed
diathesis-stress model
- a psychological theory that attempts to explain behaviour as a predispositional genetic vulnerability expressed as a result of stress from life experiences.
predicts that an individual with certain genes, when exposed to a certain environment, is more likely to develop the condition that someone with the gene, but not exposed to the environment
niche-picking
- way for genetic and environmental factors to dynamically interact
genetic predisposition causes the individual to select certain aspects of the environment, which in turn can influence their behaviour
epigenetics
the study of how your behaviours and environment can cause changes that affect the way your genes work
MAOA gene
- aka the ‘warrior gene’
- a gene carrying the aggression trait down to individuals
signals from cells to produce MAOA enzyme
- a gene carrying the aggression trait down to individuals
MAOA enzyme
an enzyme that breaks down neurotransmitters in the synapse
MAOA-L
- Low expression variant of gene
Having this gene means less MAOA is produced
concordance rate
- the correlation found between the heritability of a topic
- the higher the genetic relationship, the more similar the individuals will be if the characteristic being studied is inherited
concordance rates will increase is heritability is high and vice versa
twin studies
- MZ (monozygotic twins): genetically identical
DZ (dizygotic) twins: no closer genetically than normal brothers/sisters
family studies
- More representative sample of the general population
- Ordinary brothers and sisters will share 50% of genes with each other
Different degrees of genetical relatedness are compared with behaviour
- Ordinary brothers and sisters will share 50% of genes with each other
twin studies and concordance rates
Measure concordance rates of a particular trait across the two different types of twins (and maybe across other family relationships as well)
in context: refers to the chance that one twin will have a particular trait given that the other twin has it
twin studies use
- Twin studies reveal the power of genes, but usually also hint at the role of the environment
This means that even with sharing identical genes and being raised in similar environmental and social setting, there isn’t 100% change that one twin will develop a disorder even if the other has it.
family/kinship/pedigree studies
- More representative sample of general population
Child inherits half their genes from each parent- Shares 50% with sibling
- Grandparents and grandchildren share 25%
- First cousins share 12.5%
In family studies, these different degrees of genetic relatedness are compared with respect to specific traits of behaviour
genetic similarities
Greater the genetic similarity (relatedness), the greater the genetic influence
strengths and weaknesses of twin studies
- Produced great deal of data in support of biological roots of disorders - has helped psychologists to stress prevention for those who are vulnerable to such disorders
- High cross-cultural reliability of concordance levels
- MZ twins are now rarely separated at birth and raised in a totally different environment, yet this is necessary to substantiate claims as it commonly occurred in the past
MZ twins reared together share many of the same experiences. DZ twins reared together may not share the same experiences due to levels of attractiveness or temperament
natural selection
- Survival of the fittest will pass on their genes to their next generation
Adaptation- Disgust behaviour to avoid pathogens
what is evolution
- Adapting to one’s surroundings
- Best adapted = better chance of surviving
- Strongest mate –> produce offspring who are stronger
- Charles darwin
theory of natural selection
- Species require adaptive characteristics to survive
- Species who have characteristics better suited to the environment will be more likely to breed and pass on their traits
Over generations the results of natural selection is that species develop characteristics that make it more competitive in its environment = adaptation
- Species who have characteristics better suited to the environment will be more likely to breed and pass on their traits
mutations
- essential to evolution
Every genetic feature in every organism was, initially the result of a mutation. The new genetic variant (allele) spreads via reproduction, and differential reproduction is a defining aspect of evolution
differntial reproduction
comparing the successful reproduction rates of two groups of individuals in the same generation of a species population, each exhibiting a different genetically determined characteristic or genotype.
useful adaptations
- Psychologists believe that if a behaviour exists today, then it must be a useful adaptation that has helped us survive and reproduce, a concept know in evolutionary theory as ‘survival of the fittest’
- Point out that despite the wise diversity of human beings in different cultures scattered all over out planet, there are some reactions that seem to be almost universal - arguing that is because responses are adaptive
○ E.g:
§ Response of disgust to the smell of rotten eggs
§ Ideas of what is attractive in a mate
Fear or dislike of spiders and snakes
- Point out that despite the wise diversity of human beings in different cultures scattered all over out planet, there are some reactions that seem to be almost universal - arguing that is because responses are adaptive
testability
lack of empirical evidence (you can’t “observe” anything evolutionary)
falsifiability
the capacity for a theory to be proven wrong.
speculations about the environment
- Evolutionary adaptation is always adaptation to a certain environment
- To suggest evolutionary explanation of a trait, you need to have knowledge about the environment in which this trait evolved.
However, our knowledge of the environments in which homo sapiens evolved as a species is scarce. A lot reasoning in this field, arguably, is speculative.
- To suggest evolutionary explanation of a trait, you need to have knowledge about the environment in which this trait evolved.
retrograde amnesia
Describes amnesia where you can’t recall memories that were formed before the event that caused the amnesia
Usually affects recent memories, not ones from years ago
anterograde amnesia
Condition where a person is unable to create new memories after an amnesia-inducing event
May involve partial or total inability to remember events that have happened
declarative memory
The recollection of facts - whether as part of a specific event of just as unrelated information
Episodic (declarative) memory
Memory involving connections to times of places (e.g. Birthdays)
Semantic (declarative) memory
Simple facts that can be recalled but not linked to any specific episode of time (e.g. Capital cities, types of animals)
