Evolutionary Psychology - Lecture 2: Nature and Nurture Flashcards
Biology from a psychological point of view and general significance
Shapes views on nature vs nurture debate and position on other things such as academic, political and social implications -> gender, differences in sexual orientation, intelligence, race and aggression
Is Biology destiny?
No - need to understand that genes’ effects are mediated by environment
Genotype
What is inherited
Broad - The set of DNA molecules contained in nucleus
Personalised - A genotype particular to a trait
Phenotype
What develops
An organisms physiology, anatomy, behaviour
Breakdown of DNA
Body -> Cell -> Nucleus -> Chromosomes - 22 autosomes and 1 sex chromosome - DNA organised into 23 sets of chromosomes - 1 part of each set from each parent -> DNA -> DNA Sequence - ATCG -> this is what is analysed
Chromosome
Thread-like structures contained in the cell nucleus. Each chromosome is a DNA molecule. Chromosomes occur in pairs. Human somatic cells usually contain 23 pairs
Gene
A stretch of DNA that produces a specific protein
Allele
Alternative forms of gene at same locus (position of gene on chromosome)
Homozygous
When an organism possesses 2 identical alleles for a particular trait
Heterzygous
When an organism possesses 2 different alleles for a particular trait
Dominant
An allele that manifests it effects in both homozygotes and heterozygotes
Recessive
An allele that manifests it effects in only homozygotes
Polygenic inheritance
A trait whose phenotypic expression is influenced by many genes e.g. most psychological traits
Who founded PKU and experiment he did?
Asbjorn Folling did a urine test and found increased levels of PKU led to severe mental retardation
Full form of PKU
Phenylketonuria
What is PKU
“Inborn” metabolic disorder - causes vomiting, seizures, hyperactivity, retardation
How many white infants in USA does PKU affect?
1/10,000
What causes PKU?
Single recessive gene on chromosome 12
Normal pathway of phenylalanine
Enzyme phenylalanine hydroxylase (PAH) -> tyrosine
PKU pathway of phenylalanine
No enzyme -> Phenylpyruvate
What does phenylpyruvate do?
It is toxic to developing nervous system
Side effects of PKU
Blood levels of phenylalanine elevated
Prefrontal lobe damage
What can diet do in terms of PKU (Herzberg & Diamond 1993)?
Can intervene in effects of PKU by changing environment -> nature and nurture act together
Early application of diet reduces, but does not eliminate, cognitive deficits
Diets very hard to comply with “a diet devoid of meat, fish, dairy products, breads, nuts, and many other foods. Keeping this diet is difficult and PKU children must take a food additive in order to get enough protein”
What was the Dunedin study able to do?
Maintain high retention growth
Warrior gene
On x chromosome, the warrior gene affects the function of enzyme Monoamine oxidase A (MAOA) -> affects metabolism - the way the body processes various neurotransmitters in the brain
Known to be “genetic cause” of violent behaviour
What is the function of MAOA?
Metabolise neurotransmitters such as norepinephrine, serotonin, and dopamine
What do a number of different mutations causing warrior gene do?
Reduction in performance of MAOA and lowers abilities to metabolise neurotransmitters shown both in animal and human studies
How was it looked at as to how genetic makeup interacted with environmental diffs regarding PKU?
Along with physical assays, looked at extensive documentation of childhood experiences
Graph interpretation
High levels of MAOA = small differences, whereas low levels of MAOA in severe treatment = really high differences
Why is it wrong to think that genes inevitably lead to violence in certain people?
Need to know and understand how genes affect behaviour but can also intervene to change consequences of genes
Why are corelations not always causal relationships?
Not just genes that run in family, but also shared family culture
Statistical corelation
Any kind of relationship between 2 variables - not necessarily causal
3 things that could cause corelations
Randomly via chance 3rd variable Causal relation (causation) could be opposite direction to corelation
Heritability
The proportion of variation in a population that is attributable to genetic differences
Heritability depends on the range of typical environments in the population that is studied. If the environment of the population is fairly uniform, then heritability may be high, but if the range of environmental differences is very large, then heritability may be low. –> If everyone is treated the same environmentally, then any differences that we observe will largely be due to genes; heritability will be large in this case. However, if the environment treats people very differently, then heritability may be small.
Proportional score equation
H^2= G/V G = genetic differences V = variation
Heritability estimates do not…
- indicate the degree to which a trait can be modified
2. apply to individuals (it’s a population statistic!)
Hertiability estimates do…
- depend on the range of environments and genotypes-i.e. they are specific to the populations sampled
- assume additivity-that the genotype and environment “add up” the same way in all situations
- -> genetic differences have the same affect across all environments
What did early IQ tests remove?
Items that speculated differences between the two genders
Are IQ tests reliable?
Relatively, but validity of IQ tests causes controversy -> no universally agreed definition of intelligence - could have several domains
Correlation between IQ and shared genes chart
Shows that more shared genes = higher IQ scores/corelation -> IQ highly heritable
–> effects of shared genes are not decoupled from shared environments
3 ways we can separate the effects of shared genes from shared environments?
- Identical (monozygotic) vs non-identical (dizigotic) twins
- Adoption studies
- Separated identical twins
Adoption studies and problem with them
Can have people adopted out and see how IQ scores differ
Problem - Not randomly allocated to uncorrelated environments therefore methodical confounds
Identical (monozygotic) vs non-identical (dizigotic) twins and problems
If IQ identical then correlations of IQ scores of mono = higher IQ than di
Identical twins are treated more similarly than non-identical therefore could also lead to mono = higher IQ than IQ of di -> therefore not good for heritability study of IQ
Separated identical twins and problems
Best type of study - better when separated asap
-> if raised by relatives - living in same town e.g. same school -> bc same age - same class -> correlation in enviro -> affects correlation of IQ scores
Also fetal enviro also has impact -> shared fetal enviro in womb
-> v hard to do studies with twins
SNPs
Polymorphism can differ at one particular location -> change of 1 of DNA bases -> SNP
Can look at SNPs across whole genome -> how affects intelligence
COMT
Catechol-O-methyltransferase (COMT) is a methylation enzyme that catalyzes the degradation pathway and inactivation of dopamine.
What is associated with variation in COMT activity?
The COMT Val158Met polymorphism on chromosome 22 is associated with variation in COMT activity.
What does COMT affect?
Affects dopaminergic physiology, prefrontal cortex (PFC) function, and cognitive performance
Association between COMT and academic achievement in Chinese cohort
Kids with COMT (‘IQ gene’) did worse in test -> led to increased cognitive function but also more prone to stress/anxiety -> shows intellectual performance in difference enviros -> No one major gene is responsible for intelligence - is 1000s of genes with small effects
Social and political implications about high heritability of IQ
Approx. 10% difference between black and white ethnicities’ IQ scores on average
-> There is a clear difference between the 2 ethnicities’ IQs but it isn’t solely caused by genetics
What heritable is IQ according ot Herrnstein and Murray?
Highly hertiable - at least 50%
Herrnstein and Murray’s theory on IQ and faults with them
- There are major differences between ethnic groups and classes in IQ -> True
- IQ tests measure intellectual ability -> Debatable as intelligence isn’t defined
- IQ highly heritable -> Methodological flaws - SNPs polymorphisms show substantial heritability
- Highly heritable traits cannot be changed -> False opposition between nature and nurture
therefore…
Ethnic and class differences are genetic
Ethnic and class differences cannot (and should not) be changed
-> Conclusions don’t necessarily follow because it could be enviro differences between different ethnicities and class differences
According to H&M’s argument what is a waste of money?
Spending public money on welfare and public education programmes for different groups as changes in differences of IQ between different ethnic groups can’t happen, as these differences are fixed
H&M Bell Curve/Gottfredson 1999 - IQ predicts social success
People’s IQs sit somewhere on a bell curve which predicts a lot of things:
There is a corelation between IQ scores and social outcomes -> confounding factors affect social outcomes -> higher socioeconomic backgrounds leads to better access to better education -> Higher IQ test score
Jim Flynn and the Flynn Effect
If you look at the IQ scores worldwide for generations, they have been substantially increasing -> must be due to enviro changes not genetics
therefore. ..all around the world increasing IQ scores means IQ can be changed
- > As a result H&M claim is wrong
What does the Flynn effect argue in regards to heritability of IQ?
Intellectual performance can be changed, but doesn’t necessarily argue against high heritability of IQ
Lewontin’s argument – different causes of within vs between group differences
Within group: Enviro variation is uniform -> all differences are due to genes
Between groups: 2 different enviros that are uniform lead to differences in genes due to their separate conditions
IQ & ethnicity when children raised together - Scores of residential nursery kids on 3 nonverbal IQ tests
All very much similar -> shows heritability of IQ scores aren’t necessarily a factor for accounting in differences between ethnic groups
