1. Chapter 4 Biology and Crime
Lee Ayers-Schlosser, Southern Oregon University

2. Chapter Objectives (1 of 2)
Learn the history of biological explanations of criminal behavior. This includes early biological theories and their policy implications, including eugenics.
Understand the methodologies used by scientists in their attempt to separate nature (genetics) from nurture (environment). This includes twin studies, adoption studies, and molecular genetics.

3. Chapter Objectives (2 of 2)
Grasp the known biological correlates of crime, which range from neurotransmitters to biological harms such as lead poisoning.
Understand biosocial theories of criminal behavior and how policy implications differ between modern biosocial explanations and early biological theories.
Understand the basis of evolutionary theories of criminal behavior and to link this with a specific evolutionary theory.

4. You Are the Criminologist
Can Biological Risk Markers Identify Potential Criminals?
Futuristic fiction: An instrument can be used to screen for a particular biological trait as a predictor of violent behavior.
Do you think that there is a genetic component to criminal behavior?
What kinds of ethical dilemmas would such an instrument create?

5. Early Biological Theories (1 of 2)
Early history of criminology (many early criminologists were physicians)
Theory: the presence of certain physical traits makes criminal behavior more likely

6. Early Biological Theories (2 of 2)
1. Phrenology
2. Lombroso’s “born criminal”
3. Physical deficiencies
4. The XYY “supermale”
5. Somatotype theory

7. Phrenology Exterior of the skull reflects the mind
Bumps on the head indicate criminal tendencies

8. Lombroso’s “Born Criminal” (1 of 3)
Cesare Lombroso
19th‑century Italian physician
Led the movement from classical school to scientific positivism
Major contributions
Study of the individual offender and crime conditions
Application of statistical methods to data collection and analysis, as well as multiple‑factor analysis
Use of typological methods to classify and study criminals and examine criminological phenomena

9. Lombroso’s “Born Criminal” (2 of 3)
Atavism
Criminals as amoral, not fully evolved
Physical traits
Low foreheads
Broad noses
Small cranial capacities

10. Lombroso’s “Born Criminal” (3 of 3)
Types of criminals
Insane
Idiots, drug addicts, moral degenerates
Criminaloids
Those who have physical stigmatas and whose moral degeneracy is less pronounced
Criminals by passion
Passion (like love, hate, honor) fueled their criminal rage

11. Physical Deficiencies
Charles Goring
Criminal behavior related to defective intelligence
Earnest Hooten
Criminals physiologically inferior
Physical traits
Low foreheads
Pinched noses
Compressed faces
Narrow jaws

12. Somatotype Theory (1 of 3)
Developed by William Sheldon (supported by the Gluecks at Harvard)
Body build (somatotype) linked to:
Behavioral tendencies
Temperament
Life expectancy
Susceptibility to disease

13. Somatotype Theory (2 of 3)
Basic body types
Endomorph
Fat, soft, and round
Tend to be extroverts
Ectomorph
Thin and wiry
Easily worried, sensitive, and introverted
Mesomorph (most criminals)
Muscular
Gregarious, aggressive, assertive, and action oriented

14. Somatotype Theory (3 of 3)
Explanations
Those with muscular builds tend to enjoy the physical activity involved in crime.
Mesomorphic body type may have an advantage in the rough‑and‑tumble activities of street crime.
Mesomorph is perceived as a threat and is therefore more likely to be arrested and/or incarcerated.

15. The XYY “Supermale” Chromosomal abnormality (extra Y chromosome)
May be more likely to engage in criminal behavior (but not violent behavior)
Extremely rare chromosome structure (less than 0.1% of total male population)

16. Policy Implications of Early Biological Research
Focuses on single factors that cannot be changed
Policy solution: remove these individuals from society
Eugenics—forced sterilization

17. Modern Biological Approach (1 of 2)
Despite the tarnished legacy, there has been a comeback in biological research in recent years.

18. Modern Biological Approach (2 of 2)
1. Behavioral genetics
2. Biological correlates of criminal behavior
3. Biosocial theory
4. Evolutionary theory (sociobiology)

19. Behavioral Genetics (1 of 5)
Can criminality be inherited?
Family studies
Twin studies
Adoption studies
Molecular genetics

20. Behavioral Genetics (2 of 5)
Family studies
Early studies traced family history (Jukes)
Modern studies look at parent’s crime (Sampson and Laub)
Findings: Parental crime consistently predicts children’s criminal behavior.
Criticism: Environment could easily explain this finding.

21. Behavioral Genetics (3 of 5)
Twin studies
Compare monozygotic (MZ) and dizygotic (DZ) twins
Findings: MZ twins have higher concordance rates than DZ twins.
Criticism:
People may treat MZ twins more similarly
MZ twins more likely to share friends (including delinquent peers)

22. Behavioral Genetics (4 of 5)
Adoption studies
Compare criminal record of adopted children with their biological and adoptive parents.
Findings: Children’s criminal behavior relates more to biological parents.
Criticism: Adoption agencies might have biased placements.

23. Behavioral Genetics (5 of 5)
Molecular genetics
Isolates particular genes that may be related to criminal disposition
Helped by Human Genome Project
Findings: Some potential genes have been identified (e.g., predisposition for antisocial behavior).
Criticism: Any particular gene will have only minimal effect on human behavior.

24. Biological Correlates (1 of 2)
Physiological differences exist between criminals and noncriminals.
A wide range of factors potentially contribute to criminal behavior.

25. Biological Correlates (2 of 2)
1. Neurological factors
2. Autonomic nervous system
3. Biological harms
4. Hormones

26. Neurological Factors (1 of 3)
Direct measures of the brain
Prefrontal cortex
Executive functions (e.g., cognition, attention, impulsivity)
MRI and PET scans analyze brain structure and activity
Differences in the frontal lobe exist between criminals and noncriminal control groups

27. Neurological Factors (2 of 3)
Neurochemical measures
Neurotransmitters (like serotonin) allow cells to communicate with each other.
Low levels of serotonin are linked with impulsive and aggressive behavior.

28. Neurological Factors (3 of 3)
Indirect measures
Use IQ and other neuropsychological tests to predict delinquency
Test executive functions (which reflect differences in brain functioning)
Potentially reflect underlying neurological deficits

29. Autonomic Nervous System
Controls how the body reacts to stimuli (heart rate, gland secretions)
Some criminals have lower resting heart rates than noncriminals.
Studies of skin conductance (sweat) yield mixed results.
Criminals potentially have low levels of arousal.

30. Biological Harms (1 of 3) Perinatal risks linked with criminality
Smoking (cigarettes, marijuana)
Alcohol consumption (fetal alcohol syndrome)
Delivery complications
Low birth-weight children
More pronounced effect in unstable families

31. Biological Harms (2 of 3) Environmental toxins Lead exposure
Highly toxic substance (especially for young children)
Found in lead paint and leaded gasoline
Can cause serious health and behavioral problems
Linked to delinquent behavior

32. Biological Harms (3 of 3) Nutrition and diet
Focus on high levels of sugar and junk food intake
Relates to antisocial behavior, irritability
Some studies showed that hypoglycemia is linked with violent, impulsive behavior
Not well supported by research

33. Hormones Testosterone (male androgen) Premenstrual syndrome (PMS)
Higher levels linked to antisocial, aggressive behavior
Premenstrual syndrome (PMS)
Relationship to female offending unsupported by research

34. Biosocial Theory
Combinations of environmental and biological risk cause criminal behavior
1. Life-course-persistent offending
2. Personality-based theory
3. Female delinquency

35. Life-Course-Persistent Offending
Developed by Terrie Moffitt
Adolescent-limited (AL) offenders
Criminal behavior limited to adolescence
Life-course-persistent (LCP) offenders
Chronic offending starts early in life
Caused by neurological deficits and ineffective parenting

36. Personality-Based Theory
Developed by Hans Eysenck
Personality traits driven by underlying biology cause crime.
Children with low arousal will be difficult to socialize.
In criminal families, low arousal might prevent children from learning criminal behavior.

37. Female Delinquency
Early onset of puberty is linked to criminal behavior.
This is true for girls in coed schools, but not for those in all-girls schools.
Conclusion: Girls who start puberty early attract the attention of older, crime-prone males, which may lead to delinquency.

38. Evolutionary Theory (1 of 2)
Uses principles of evolution to explain modern human behavior
Research
Rape
“Cads and dads” theory
Criticism
Difficult if not impossible to test
Evidence sometimes runs counter to predictions

39. Evolutionary Theory (2 of 2)
Rape
Evolutionary processes allow males who are pushy and aggressive in the pursuit of sex to pass on their genes successfully.
“Cads and dads” theory
Alternative strategies for reproductive success
Cads—pretend caregivers who really want to reproduce with as many females as possible
Dads—invest time and energy to help nurture and raise offspring

40. Summary Many biological factors involved in criminal behavior:
Inherited
Results of biological harm
Biological factors contribute to criminality in certain environmental circumstances.
Humans may be partially driven toward crime by natural forces beyond their control.

41. Biological Theories Criticisms (1 of 2)
Lombrosian fallacy
Incarcerated persons not representative of criminals in general population
Bias from social structure and criminal justice system

42. Biological Theories Criticisms (2 of 2)
Ignores some types of crimes
White-collar
Organized
Political crime
Focuses on aggression or antisocial behavior in children and street crime in adults

43. Policy Implications (1 of 2)
Fears ethical problems
Biology not necessarily destiny
Provide unsound justifications for the control of minority populations
New eugenics
Gene therapy
Discrimination based on presence of biological risk indicators

44. Policy Implications (2 of 2)
Criminality as a public health problem
Prenatal care for at-risk mothers
Strengthen environmental counterbalances for children with biological risk indicators

45. Conclusion
Lessons from the biological school are limited to certain crimes and offenders.
More research is needed.
Nature vs. nurture relationship
Interdisciplinary study with criminologists and physical and medical scientists