UNIT 2 - AC2.1 - BIOLOGICAL THEORIES Flashcards
what did cesare lombroso propose in his theory
that people are ‘born criminal’ and this can be determined by physical features
that criminality is inheritable
examples of atavistic features
large jaw
upturned nose
large chin
long arms
fleshy lips
large ears
what did lombroso study
facial and cranial features (383 dead criminals and 3839 living ones)
concluded that 40% of criminal acts can be accounted for by atavistic features
murderers - bloodshot eyes and curly hair
sex offenders - thick lips and protruding ears
what did william sheldon propose in his theory
he believed there is a correlation between body types and behaviour
definition of somatotype
body shape
three somototypes
endomorphic - fat and soft, sociable and relaxed
ectomorphic - thin and fragile, introverted and restrained
mesomorphic - muscular and hard, aggressive and adventurous
sheldons evidence
sample of 400 male college students
200 delinquents and 200 non- delinquents
200 delinquents further split into delinquents and criminal delinquents
sheldon took photographs of all participants and rated their mesomorph on a scale of 1-7
findings - higher the delinquency, higher the mesomorphy rate
what did sheldon find with his correlation study
most convicts were mesomorphic, some endomorphic and little ectomorphic
brain abnormality theory
phineas gage
damage to the prefrontal cortex could result in an altered behaviour pattern
raine et al (1994)
PET scans used to study impulsive killers and damage was found to the prefrontal cortex
McIsaac et al (2016)
those who suffered head injuries are twice as likely to end up in prison
neurochemical theory
low levels of serotonin are linked to aggression
(scerbo and raine 1993) meta analysis of 29 studies found low levels of serotonin in anti-social adults and children
what does the XYY theory (jacob et al 1965) suggest?
that chromosomal abnormality can be an attributable connection to crime
what are the sex chromosomes for a male and a female?
female - XX
male - XY
what is a super male?
a male with an extra Y chromosome (XYY)
why have supermales been of interest to criminologists
suggested that they are more aggressive and more likely to use violent behaviour than males with one Y chromosome
how many supermales are there in the prison population
15/1000 in prisons in comparison to 1/1000 in the general population
what are monozygotic twins (MZ)
share 100% of their DNA
indentical twins
from one fertilised egg
what are dizygotic twins (DZ)
fraternal twins
share 50% of DNA
from two seperate eggs
raines twin study (1993)
conducted a review of all twin studies
all thirteen studies of crime show greater concordance rates for criminality in MZ that DZ twins
conclusion - if one MZ twin is criminal, it is highly likely the other will be too
what does concordance rate mean
in agreement / harmony
what is the principle of adoption studies
the comparison of criminals with both their biological and adoptive parents (nature/nurture)
hutchings and mednick (1975)
studied 14,000 adopted children
found high proportion of boys with criminal convictions had biological parents with criminal convictions
link between aggression and genetics
mednick et al (1994)
found no relationship between number of criminal convictions of adopted parents + their children but did with biological parents
