Behavioural Genetics [W1]
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Def: Sexual Selection
mate choice based on
Who likened the mind to a Swiss army knife?
Cosmides & Tooby (1992)
What do Cosmides & Tooby mean re: mind is like a Swiss army knife?
made up of specialised modules designed to solve specific problems–not general learning device. Central idea to evolutionary psych
Def: genotype
set of genes an organism posesses
Def: phenotype
appearance of the organism
Def: alleles
pair of genes that control the same trait
identical pair of alleles is _________
homozygous
different alleles of same gene are __________
heterozygous
Def: heritability
the estimate of how much genes contribute to the variation in a phenotypic trait in a given population
Def: epigenetics (vis a vis behaviour)
the study of how environmental factors influence gene expression
Explain the rat study by Tryon (1934)
Rats in maze to test cognitive abilities. Interbred rats who made fewest mistakes over generations –> ‘bright group’ (few errors). Interbred rats who made most mistakes over generations –> ‘dull’ group (most mistakes). Less overlap through successive generations. Conclusion: some elements of intelligence are determined by genes. Intelligence is likely a polygenic trait bc several generations required for groups to separate.
Explain the study by Cooper and Zubeck (1958) re: rats in restricted environments
Raised rats in restricted, normal and enriched environments. ‘Dull’ rats raised in enriched environments improved. ‘Bright’ rats weren’t as good if raised in restricted environments. Conclusion: experience ‘overcomes’ genetic influence
According to Plomin and DeFries (1998) in studies of intelligence, correlations between identical (monozygotic) twins exceed those for fraternal (dizygotic) twins in_______, __________, _________, _________.
Verbal abilities, adulthood, spatial abilities, childhood
Def: polygenic trait
several genes involved
Explain rat study by Searle (1949)
Compared ‘bright’ and ‘dull’ rats on 30 behavioural tests. Conclusion: selective breeding affects multiple (not single) traits
def: monozygotic (twins)
identical; develop from sign egg that splits after being fertilised by single sperm ==> share 100% of genes
def: dizygotic (twins)
fraternal; develop from two separate eggs, fertilised by two separate sperm ==> share 50% of genes (same as any other siblings)
Plomin and DeFries (1998) twin studies (intelligence). Explain.
compared twins (MZ/DZ) on range of cognitive tasks; conclusion: strong evidence for genetic influence on variations in intelligence, that doesn’t decrease over. Twins raised in similar environments –> diff in scores more likely due to genes [high heritability]. Twins raised in very different environments ==> lower heritability score
Plomin and DeFries (1998) adoption studies (intelligence). Conclusion?
Evidence for strong genetic influence on variations in ‘intelligence’
What part of cell contains entire genome?
nucleus
def: dendrite
a branch that extends from the cell and receives information from other cells
def: dendritic spine
a protrusion on a dendrite that increases the SA of the dendrite
def: nucleus
structure w/in cell that contains genes and chromosomes
def: nuclear membrane
the membrane surrounding the nucleus; separates chromosomes from rest of cell; has small pores to allow nucleic acids and proteins to pass through