ac2.1 biological theories Flashcards
Lombrosos theory
Argued physics shape of the head and face determined the “born criminal”
A “born criminal” is an atavism where physical makeup mentality and instincts are similar to a primitive man
His common foundings were large ears, pronounced jaw and sloping broe in criminals which are indicators of low intelligence
He argued this meant individuals wete not responsible for their actions because its inherited
Strengths of Lombrosos theory
Supported by Charles Goriny who found low order intelligence in convicts
Recent Chinese study put ID photos of convicted criminals through an AI programme which identified the male criminals 83% of the time and wrongly flagged only 6% of innocent men
Focuses on preventing not punishing crime
Criticisms of Lombrosos theory
Didnt use control group of non-criminals
Gender bias- theorised women are less evolved so less likely to commit crime so females that were criminal had masculine features
Not everyone with atavistic features is criminal and not all criminals have them
Lombrosos 3 identifications of criminals
Born criminals- atavistic
Insane criminals- mental illness
Criminaloids- predisposed characteristics
William Sheldons somatotypes theory
Sheldon uses body measurements to correspond with personality.
Endomotphic(fat and soft) tends to be sociable and relaxed
Ectomprphic(thin and fragile) are introverted and restrained
Mesomorphic(muscular and hard) tend to be aggressive and thrill seeking
Sheldon and Glueck research on body types
800 delinquents compared to a matched sample of non- delinquents found that delinquents more likely to be mesomorphs
Strengths of Sheldons theory
Sheldon used a large sample of 200 and had a control group of non-offenders
The most deliquent individuals in the sample had more extreme mesomorphic body shapes
Other study- Glueck
Found 60% of offenders in their deliquent sample were metamorphs comapred to 31% in non-delqiquent sample
Criticisms of Sheldons theory
Doesn’t account for the endomorphs and ectomorphs that commit non-violent crimes
Social class is the cause of mesomorphy because criminals are mostly working class males in manual labour
Criminality causes somatype because they need to be able to physically succeed
Identical twins
Non-identical twins
Monozygotic twins
Fraternal or dizygotic twins
Genetic theories: twin studies
Early research found higher concordance for MZ thsn DZ twins which supports suggestion of genetiv influence. However early research was flawed by its poor methods for determining zygocity anf small samples.
Recent studies found lower estimates for the heritability of criminality
Lange twin studies
10/13 of the MZ twins had a co-twin also in prison
2/17 of the DZ twins had a co-twin also in prison
Concordance rate for MZ twins that showed criminal tendencies was much higher
Christiansen twin studied
Examined over 3500 twin pairs in Denmark
Male MZ 35% Male DZ 13%
Female MZ 21% Female DZ 8%
Concordance rates are low even for MZ twins showing environment still plays a large part
Role of gender in criminal behaviour
Strengths of twin studies
Because MZ twins are identical it is logical to examine whether their offending behaviour is also identical
Reliable- large scale studies found higher concordance for identical twins than fraternal
Criticisms of twin studies
Parents treat MZ twins more alike than they do DZ twins and so MZ twins feel closer and shoe similarity in their criminality too
Higher concordance rates between identical twins may be due to them sharing same environment
It’s impossible to measure the effects of genes separately from environmental effects
Genetic theories: Adoption studies
This theory looks at relatives, twins and siblings that are adopted at a young age which means they share genes but not the same environment as their parents.
By taking environment out the picture we can be sure genetics are the cause of criminality.
Hutchings and Mednick
studied 14,000 adopted children and found a high proportion of boys who had committed a crime had biological parents with criminal records
Mednick et al
found significant correlation between the number of criminal convictions of their biological parents and their children
If the child is more similar to their adoptive parents than biological parents we can suggest criminality had an environmental cause
Strengths of adoption studies
Overcome problem in twins studies where biologically identical twins are brought up in same household making it impossible to separate genes and environment
Findings of adoption studies supports genetic explanations
Criticisms of adoption studies
Adopted children are often placed in environments similar to their birth family producing similar behaviour
Many children are not adopted after birth and spend some time with their biological family which may be the true cause of criminality
Genetics XXY syndrome- Jacob et al
XYY are more aggressive and potentially criminal than XY men
XYY men are overpopulated in the criminal population
15 per 1000 criminal population
1 per 1000 general population
Stengths of XXY theory
Jacob found an association between XYY and offenders imprisoned for violent behaviour
Prince and Whatmore found links between XYY syndrome and property crime
Criticisms of XYY theory
Even if some violent offenders have XYY syndrome this doesnt mean this was the cause of their violence
XYY males are tall and well built so fit stereotype of violent offenders and more likely to be labelled as such by court
Case of Phineas Gage
Severe damage to frontal lobe after an accident on the railroad in 1848
Developed a brain infection
Damage to prefrontal cortex (controls emotions and regulates behaviour) caused change in personality
Examples of brain diseases that increase likelihood of committing crime
Prenatal smoking/ alcohol
Prefrontal cortex/ impulsive behaviour
Prefrontal cortex is smaller in men than in women
Strengths of brain injuries and disorders
In extreme cases like Gage and Whitman brain injury led to major changes in personality including criminal behaviour
Prisoners are more likely than non prisoners to have brain injury
Criticisms of brain injuries and disorders
Brain injury is rare so personality is a more important factor
Prisoners higher likelihood of brain injury could actually benthe result of criminality e.g. getting into fights
Outline how sex hormones can be linked to crime
Over production of testosterone is linked with crime like rape and murder
It increases aggression and impulsivity and so decreases fear and worry
Levels peak between puberty and early 20s which correlates with male crime rates
Hormones fluctuate for women during post-natal depression and lactation so affect behaviour and can be used to justify infanticide to shop lifting
Outline how blood-sugar levels can be linked to crime
Low blood sugar can trigger aggressive reactions and can be linked to alcohol abuse because it lowers it
Alcohol abuse reduces awareness and is linked to crime of violence
Outline how substance abuse can be linked to crime
Abuse of some other legal and illegal drugs such as crack and cocaine that correlates with violence
Outline how other substances can be linked to crime
Low serotonin levels- aggression
Vitamin B deficiency- erratic and aggressive behaviour
Tartazine- hyperactivity
Strengths of biochemical explanations
Biochemical factors are recognised by the courts and in some cases written into laws e.g. infanticide
Strong medical evidence to support that substances and hormone levels can affect judgement and aggressions
Criticisms of biochemical explanations
Effect of biochemicals on aggression might be overstated e.g. more likely to lead to verbal aggression
Might create a pre-disposition to offending but need an environmental trigger
Criticisms of biological theories in general
Most research focuses on explaining male criminality
Sample bias- not representable of criminals who dont get caught or commit minor crimes
Ignores significance of environmental factors
