1. Biological theories

2. Nature v. nurture What’s presently accepted? Inheritance & environment don’t “cause” but may “predispose” – Crime is a social definition -- Malum in se v. mala prohibita – Not all maladaptive behaviors are illegal Behavior is affected by... – Inherited characteristics – Inherited characteristics, affected by environment – Environment effects on health (injury, pollution, diet…) General agreement that biology and environment interact Sociologists, including criminologists, tend to minimize biological and psychological factors – But as we learn more about the human organism, more and more winds up being explained by chemistry

3. A trip through the past: body type (“somatotypes”) Sheldon linked physique and temperament – Endomorph: Soft physique, relaxed and comfort-seeking temperament – Mesomorph: Muscled physique, active and assertive temperament – Ectomorph: Lean, frail physique, introverted temperament Gluecks found correlation between mesomorph somatotype and aggressive/antisocial/uninhibited behavior

4. Family studies - Goring Examined relationship between heredity, environment and length/frequency of imprisonment – Heredity  imprisonment? – Environment  imprisonment? Findings – Environmental factors not correlated with imprisonment Poverty, broken homes, nationality, birth order – Biological factors are correlated with imprisonment Physical size (smaller, worse off) Mental inferiority Criminal family members

5. Criticisms of Goring and family studies Failure to adequately measure environmental variables Current data does not suggest that crime “runs rampant” in families Difficult to control for environmental effects within families, as all are usually exposed to similar circumstances

6. Twin studies Difficult to control environmental variables – So, control heredity Fraternal twins: different eggs, different DNA – Can inherit different biological factors Identical twins: one egg, same DNA – Biological factors the same Look for similarities and differences in behavior – Similarities between identical twins can be hereditary or environmental; differences cannot be hereditary – If behavior of sets of identical twins is more alike than behavior of sets of fraternal twins, heredity may be important

7. Studies of identical twins -- Christiansen 6,000 pairs of male twins – Male identical twins: 67 pairs where at least one was registered as a criminal. In 36% of these pairs (n = 24) both were criminals – Male fraternal twins: 114 pairs where at least one was registered as a criminal In 12% of these pairs (n=14) both were criminals – Higher concordance for serious crimes Issue: Could higher concordance of behavior for identical twins be due to a more similar environment?

8. Twins reared apart Similar environments might make identical twins act alike, so study identical twins reared apart Grove (32 pairs separated shortly after birth); Christiansen (8 pairs). – Both found evidence that antisocial behavior can be inherited Walters - 1992 meta-analysis of 14 twin studies – Considered sample size, quality of research design – Support for hereditary basis to criminality May be difficult to control for environmental effects

9. Adoption studies Attempt to control for environmental effects Hutchings and Mednick -- biological fathers appear to influence boys’ criminality Boys not delinquent Boys delinquent Bio. father Not criminal 69%51% Bio. father criminal 31%49%

10. Number of court convictions of biological parents (not adoptive parents) influences youth criminality, but only for property crimes Other influencers: – Socioeconomic status of biological and adoptive parents – Personality disorders of biological parents – Number of placements before adoption – Criminality of biological and adoptive fathers interacts Issues with adoption studies – Low sample sizes – Recent studies found link between heredity and behavior only for minor and property crime (far more frequent than violent crime) – Adoptive parents often more law-abiding than general population Mednick -- cont’d

11. Brain chemistry Neurotransmitters – Chemicals that transmit electrical impulses in the brain – Levels affected by medication, diet, drug use, stress – Imbalance may promote aggressive or compulsive behavior Violence, drug use Hormones – Testosterone: Documented role in animal aggression, effects found in human research Issues – Causal order: Aggression may be the cause (not the effect) of high levels of hormones – Booth and Osgood study Association between testosterone and adult deviancy BUT – effect of high levels mediated by social integration High levels  lack of social integration  aggression

12. Central nervous system (CNS) Brain and spinal cord Cerebral cortex - outer portion of the brain Four lobes (frontal, temporal, parietal, occipital) Frontal and temporal lobes control goal-directed behavior, impulses and emotions

13. CNS and criminal behavior Some evidence that abnormalities in the lobes may be associated with violent and sexual offending – Frontal dysfunction may be associated with violent offending – Temporal dysfunction may be associated with sexual offending – Violent sexual offenders may have both dysfunctions Issues – Research methodology - no sampling (with a hammer, everything’s a nail) – Precise path to offending is unknown

14. Autonomic nervous system (ANS) Controls involuntary functions: Blood pressure, heart activity, intestinal activity, hormone levels “Fight/flight” situations: ANS prepares body to respond – Blood from stomach to muscles – Increases respiration – Stimulates sweat (increases electrical conductivity of skin)

15. Anxiety (e.g., conditioned fear of being punished for telling a lie) is basis for lie detection Anxiety may be the primary socializing agent for children – They behave properly to avoid anxiety of punishment Hypothesis that defective response can interfere with socialization – Antisocial persons might be more difficult to “condition”, so they are less likely to fear punishment ANS - continued

16. Environmental-biological factors: Drugs and alcohol Alcohol in lower doses increases aggressive behavior, especially in males Marijuana may reduce but does not increase aggression Opiates may reduce aggression – Chronic use may increase aggression – Withdrawal from opiates may also increase aggression Methamphetamine, PCP and LSD may increase aggression – May be especially true for those predisposed to violence – Police anecdotes about extreme violence and strength displayed by persons high on Meth and PCP No direct evidence of effect of cocaine on violence – Association between violence and areas where rock cocaine is used (inner cities) – Note - “rock” cocaine is much more concentrated

17. Other environmental-biological factors Lead in diet may affect brain functions – May cause hyperactivity and antisocial behavior in children Head injury with brain damage may cause violent behavior – Decrease cognitive and social skills – Headaches and irritability – Damage frontal and temporal lobes, increasing anxiety, anger and hostility Delivery complications correlated with violent offending – Particularly when parents had psychiatric problems