Psychology of Criminal Behaviour: A Canadian Perspective Chapter 2: Theories of Crime:
Biological and Evolutionary Explanations
CHAPTER 2: Theories of Crime: Biological and Evolutionary Explanations
1. Describe the range of biological explanations of crime, which include genetics,
neurochemistry, hormones, psychophysiology, and more.
2. Explain the basic principles of evolutionary psychology and demonstrate how these
principles are used to understand crime in general as well as more specific forms of
crime and specific types of criminal offenders.
3. Demonstrate that biological and evolutionary theories of crime are as much about the
environment as they are about biology and evolution.
4. Demonstrate that biological and evolutionary explanations are not incompatible with
traditional theories of crime (e.g., social learning theory, presented in Chapter 3), but
rather are complementary.
There are multiple pathways to crime. The focus in this chapter has been on evolutionary
and biological explanations. Multiple pathways exist within each perspective, including
biological factors such as genetics, neurochemistry, hormones, and psychophysiology.
Evolutionary perspectives are complex, and evolution is comprised of a series of micro
evolutionary theories (e.g., life history theory, frequency dependent selection).
Biological and evolutionary explanations of crime underscore the importance of the
environment. Environmental insults (e.g., a mother who drinks during pregnancy) change
the “biological” makeup of an individual such that he or she is now predisposed to a
future criminal lifestyle. Evolutionary mechanisms were shaped by the environment,
albeit a distant one. Evolution itself has determined our minds such that they adapt and
change to current environmental cues. The theory of evolution has more in common with
“environmental” theories such as social learning (discussed in Chapter 3) than one might
think. The only difference is that evolution focuses on the learning environment of the
entire species whereas social learning theories focus on the learning environment of an
It is a myth that evolutionary accounts of crime contradict traditional theories.
Evolutionary perspectives simply focus on providing ultimate explanations, and
traditional criminological theories focus on more proximate explanations. The
perspectives tend to complement rather than contradict. When theories do diverge it
indicates that one perspective is incorrect.
This chapter has shown that “the evidence for genetic influences on criminality is no
longer scientifically questionable” (Ellis 2008: 249). It has also demonstrated that the
path to crime is complex and that a number of biological subsystems interact with one
another to increase risk of future criminality, with the environment greatly influencing
whether certain biological predispositions will manifest.
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Evolution is uncontested in scientific circles. However, evolutionary psychology, in
particularly evolutionary forensic psychology, is in its infancy. More research from
different perspectives is required.
The link between evolutionary and biological explanations of crime is a natural one.
In the evolution section, we focused on psychological mechanisms that have evolved
in response to ancestral selection pressures. This does not negate the existence of evolved
biological mechanisms such as those reviewed in the first part of the chapter.
1. What Makes a Strong Theory?
Numerous textbooks and experts have defined the meaning of theory.
the definition here represents an amalgamation of perspectives: a theory is
an explanation of a particular phenomenon
a strong theory:
1. is parsimonious;
2. clearly identifies the causal mechanisms and corresponding
mediators and moderators underlying the phenomenon of interest;
3. is testable and hence falsifiable via hypotheses and predictions;
4. is based on empirical data and is modified in response to new data;
5. possesses interdisciplinary compatibility; and
6. respects gender, ethnicity, and culture.
7. “Does this perspective provide a good theory of crime?” e.g., are
certain explanations stronger (causal evidence is presented versus
2. Background: Historical Context:
phrenology is theoretical perspective stating there is a relationship
between the shape and size of a person’s head and his/her personality,
mental ability, and behaviours.
Spurzheim students, applied the principles of phrenology to explain why
30 women had killed their children.
Spurzheim concluded that the women suffered from an underdeveloped
part of the brain responsible for loving children.
Spurzheim failed to include a comparison group—women who had not
killed their children
phrenology eventually died out but an Italian physician, one step further
and began comparing criminals (men, and women and prostitutes), to
“normal” segments of the population
Lombroso argued that criminals possess distinctive physical features
(sloping foreheads and twisted lips not observed in his “normal” subjects.)
referred to these features as atavisms
suggested that criminals were evolutionary throwbacks who had more in
common with Neanderthals than modern-day man
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Lombroso remains the “father of criminology.”
Darwin published On the Origins of Species in 1859, almost 17 years
before Lombroso published the first volume of The Criminal Man.
Darwin posited that humans had evolved from ancestral species via the
mechanisms of natural selection.
Galton founded eugenics—the theory that was ultimately responsible for
the forced sterilization (or worse) of thousands of “unfit” individuals in
the United States during the early part of the twentieth century and for the
atrocities under Hitler’s regime (forced abortion, sterilization, and,
ultimately, death camps.
a number of social scientists have dismissed or scorned biological and/or
The study of biology and evolution has advanced considerably since
Darwin and Lombroso
3. Researching Biological Explanations of Crime:
Behavioural genetics researchers use twin methodology: are identical
twins are more likely to commit crime than non-identical twins?
Molecular biologists compare the genetic makeup of a group of
“criminals” to one of “non-criminals” to look for distinct genetic
differences between the two.
Neurochemical approaches examine how genes actually express
themselves in terms of the brain’s neurotransmitter systems.
other researchers rely on brain-imaging techniques such as computer
tomography (CT) to assess brain functions and impairment in antisocial
Defining crime is a complex task.
some researchers examine the link between biology and crime: compare
“normal” individuals to individuals who officially diagnosed with
antisocial personality disorder (ASPD), conduct disorder (CD), or
others use measures of aggression or composite indices of antisocial
behaviour obtained via self-report or from parents or teachers.
Researchers often define crime using current legal definitions, examine
biological factors to correlate or predict official criminal offending (use
the form of arrests or convictions).
Targets of study focus on males or females.
may study children, adolescents, adults, or specific groups of offenders
4. Genetics and Crime—Twins, Adoption, and Molecular Genetics:
need to disentangle genetic and environmental influences. Is criminal
behaviour a result of genes or socialized attitudes and life skills
behavioural genetics relies heavily on the study of twins and adoptions
which can help separate genetic from environmental influences
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Every human being shares about 99 percent of his or her DNA sequence
with the rest of the human species.
The percentage of DNA that humans collectively share is fixed and
accounts for our basic similarities
Behavioural genetics focuses on the remaining 1 percent of the variance
Monozygotic (MZ) or identical twins are genetically identical. They share
100 percent of their genes
dizygotic (DZ) or fraternal twins are no more alike than non-twin siblings,
sharing on average only 50 percent of that 1 percent
frequency of criminal behaviour is converted into a concordance rate that
represented the percentage of both twins classified as “criminal.”
Concordance rates would be calculated separately for MZ and DZ twins
and then compared.
A concordance rate of 30 percent for the DZ twins would mean that if one
of the DZ twins was “‘criminal,” then there was 30 percent chance that the
other DZ twin was also criminal
Evidence for a genetic contribution to crime is inferred if concordance
rates are higher among MZ than DZ twins.
Concordance rates are typically converted into a heritability coefficient—a
descriptive statistic that represents the proportion of phenotypic variance
in a given behaviour (e.g., criminal) that can be attributed to genetic
variation among individuals
more complex statistical approaches such as biometric ▯modeling have
been used to estimate heritability coefficients
statistical ▯modeling—permits the estimation of two types of
1. shared environmental factors (i.e., aspects of the environment shared
by all family members, such as living in poverty); and
2. non-shared environmental factors (i.e., aspects of the environment not
shared by all family members, such as exposure to different peer
groups or differential treatment by parents
genetic studies are about genes and are about environment.
this type of twin study may overestimate or underestimate the genetic
contribution for several reasons
1. parents are more likely to provide similar environments for MZ twins
than their DZ counterparts
2. inheritability estimates for MZ twins may be confounded by
prenatal factors that by definition aren’t necessarily genetic e.g., MZ
twins usually share one placenta and DZ twins usually have two
earlier twin studies were also criticized for using small sample sizes and
for being subject to political influence
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Adoption research has taken one of two forms:
1. parent–offspring: concordance rates (or correlations) between adoptive
parents and adoptees’“ antisocial behaviour” are compared to
concordance rates (or correlations) between biological parents and
adoptees. If the concordance rates/correlations are higher for the
biological parents and the adopted offspring than the adoptive parents
and the adopted offspring, genetic contributions to antisocial
behaviour are inferred
2. sibling–offspring: concordance rates between adoptive siblings are
compared with concordance rates between biological siblings. One
strong adoption study of 14 427 nonfamilial adoptions in Demark
between 1924 and 1947found: if both the biological and adoptive
parents had no criminal record, then only 13.5 percent of adopted sons
had criminal records; if the adopted parent had a criminal record and
the biological parent did not, this percentage increased marginally to
14.7 percent. In contrast, 20 percent of adopted sons had a criminal
record if the biological but not the adopted parent also had a criminal
record, but the highest level of criminality (24.5 percent) was observed
if both sets of parents—biological and adoptive—had criminal records.
the study demonstrate that genes play a role in explaining crime and that
environmental effects are important.
Adoption studies limitations:
1. generalizability; and
2. environments of adopted offspring tend to be more advantageous
relative to the general population,
meta-analytic review of studies (aggregating the results of 10 independent
adoption samples and 42 independent twin samples): the variance in
antisocial behaviour could be partitioned as follows: heritability,.41;
shared environment,.16; and non-shared environment,.43.
Moderators examined included: 1) zygosity determination (self-report vs.
blood typing, or both); 2) assessment method (e.g., parental ratings of
antisocial behaviour vs. teacher- and self ratings vs. official criminal
records); 3) operational definition of antisocial behaviour (e.g., psychiatric
diagnoses of conduct disorder and antisocial personality disorder vs. legal
definitions, official criminal convictions vs. overt aggressive behaviour—
e.g., gets into fights, uses a weapon frequently); 4) sex of the participants;
and 5) age of the participants.
highlights of the results of the moderator analysis: the observation that
twin studies garnered higher heritability estimates than adoption studies
and that genetic effects were slightly higher for females than males; that
the genetic proportion of variance increased with age (genes exerting more
influence during adulthood than childhood).
both genetics and the environment both contribute to variance in antisocial
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research increasingly shows that the gene–crime link is most likely not
direct but rather a function of the mediational effects of inherited
characteristics that predispose an individual to antisocial
genetics might reduce or magnifying the effects of environmental risk
behavioural geneticists: are there interactive effects between genes and
The evidence demonstrates that childhood maltreatment (e.g., physical
abuse, emotional abuse, sexual abuse, neglect) contributes to the
development of antisocial and criminal behaviour
less clear is why 50 percent of maltreated children do not engage in
delinquency, aggressive behaviour, or criminality
one study used a genetic risk continuum based on their co-twin’s conduct
disorder status and the pair’s zygosity: the experience of maltreatment (as
reported by parents) increased the probability of receiving a conduct
disorder diagnosis by 1.6 percent among children deemed “lowest genetic
risk”—i.e., MZ co-twin did not have CD diagnosis; the probability of
receiving a conduct disorder diagnosis increased to 23.5 percent among
children deemed “highest genetic risk”—i.e., MZ co-twin had CD
Molecular Genetics Research
Twin and adoption studies illustrate that there is a clear link between
genetics and antisocial behaviour (actual functional gene(s) involved has
not been identified).
The main function of a gene is to produce proteins comprised of amino
acids—the basic building blocks of life.
Proteins are responsible for the phenotypic expression of our genotype.
Faulty genes either reduce too much or too little of a particular protein.
Human genes are
Caspi and colleagues (2002), using an epidemiological study,
demonstrated an interaction between a specific gene [monoamine oxidase
A (MAOA), a sex-linked gene] and a well-known risk factor—childhood
The MAOA gene is responsible for encoding the MAOA enzyme, which
in turn is responsible for metabolizing key brain neurotransmitters such as
norepinephrine (NE), serotonin (5-Ht), and dopamine (DA), all of which
have been implicated in aggression and various forms of antisocial
The two existing versions of the MAOA gene—low activity and high
activity—are the result of apolymorphism.
Researchers found evidence for a strong gene by environment interaction
across all four measures of antisocial behaviour—conduct disorder,
violent convictions, violent disposition, and antisocial personality disorder
While maltreatment by itself had deleterious effects, its effects were
exacerbated by the presence of a low-activity MAOA gene.
Copyright © 2011 Pearson Canada Inc. 19 Psychology of Criminal Behaviour: A Canadian Perspective Biological and Evolutionary Explanations
Thus there is increasing evidence that the low-activity version of the
MAOA gene, sometimes dubbed the “warrior gene,” plays a significant
role in the expression of antisocial behaviour, particularly aggression and
more importantly, the low-activity MAOA gene only expresses itself in
the presence of certain environmental cues, such as childhood abuse or
5. Neurochemistry and Crime—Hormones and Neurotransmitters:
Genes are largely responsible for the expression of hormones and
the endocrine system regulates hormone production and distribution,
the nervous system regulates the production and function of
Hormones and Crime
The endocrine system governs more than 50 hormones
hormones are released into our bodily fluids (typically via the
bloodstream) by nine primary glands that comprise the endocrine system
(e.g., hypothalamus, thyroid, and gonads—testes and ovaries).
only specific target cells will actually respond to a given chemical
regulate metabolism, growth, and development, and impact behaviour.
imbalances may be minor, resulting in mood swings or severe, resulting in
serious illness or death
testosterone is implicated in criminal behaviour, violence and aggression,
Testosterone is a steroidal hormone of the family of androgens.
responsible for developing and maintaining male primary and secondary
The relations between aggression and testosterone is well established in
the animal world
earlier meta-analyses reached the same conclusion—the relations between
testosterone and aggression in humans is positive yet weak.
two factors moderated the effect: age and time of day testosterone
Gender, offender status, and method of testosterone or aggression
measurement did not influence the magnitude of the findings.
these studies were correlational – few if any have shown that testosterone
levels are either causally related to or predictive of future aggression
plausible that aggression actually causes testosterone levels to increase or
that some additional third mediating variable(s) is accounting for the effect
physical and chemical castration studies have shown that sexual re-
offending is reduced in offenders who have undergone chemical and/or
physical castration versus those who have not or who did not comply with
Copyright © 2011 Pearson Canada Inc. 20 Psychology of Criminal Behaviour: A Canadian Perspective Biological and Evolutionary Explanations
premenstrual syndrome (PMS), has been studied in the context of crime
and aggression and has been used (albeit rarely) successfully as a legal
defence in Britain and the United States and as a mitigating factor in
neurotransmitters are chemical messengers that operate in the brain and
are the messengers of the nervous system.
Neurons or nerve cells transmit instructional signals from one part of the
body to another and neurotransmitters play a critical role in this
there are two types of neurons—pre-synaptic (the sender) and postsynaptic
The postsynaptic cell receives the message using its dendrites.
Narrow gaps or synapses exist between the pre-synaptic and postsynaptic
Some of these synapses are electrical and some are chemical (electric
impulses are converted to chemical signals by the neurotransmitters)
Neurotransmitters are stored in synaptic vesicles.
Three neurotransmitters in particular have been studied in relation to
crime: serotonin, dopamine, and norepinephrine.
The neurotransmitter serotonin, or hydroxytryptamine (5-HT), plays an
important role in behavioural inhibition and mood regulation
produced from an essential amino acid, tryptophan.
Tryptophan is not produced naturally within the body but must be
obtained from diet (protein-based foods such as turkey and chocolate).
there is a link between a malfunctioning serotonin system and impulsivity,
irritability, and aggression – found in studies that operationalized
malfunctioning serotonin systems as low levels of serotonin, low levels of
its precursors such as tryptophan, low levels of its metabolites and faulty
serotonin receptor sites on the postsynaptic neuron
one meta-analytic review of 16 studies illustrated that serotonin levels
were substantially lower among antisocial individuals than non-antisocial
individuals – the effect was even more pronounced for individuals under
the age of 30 versus individuals over 30
The effect did not change as a function of gender, target of violence,
history of suicide, or alcoholism.
epidemiological research design was used to test the serotonin aggression
hypothesis between blood serotonin (high levels of blood serotonin mean
low brain serotonin levels).
results confirmed a moderate (positive) correlation between blood
serotonin levels and violent criminal behavior for men but not women and
results did not vary as a function of whether or not criminal behaviour was
measured officially or via self-report.
Copyright © 2011 Pearson Canada Inc. 21 Psychology of Criminal Behaviour: A Canadian Perspective Biological and Evolutionary Explanations
thus research clearly suggests that there is a correlation between a
malfunctioning serotonin system and aggression.
other research illustrates that low levels of serotonin increase impulsivity
(a known correlate of aggression) and suggests that serotonin may exert its
influence indirectly on aggression through the mediator of impulsivity or
perhaps negative mood.
The release of dopamine causes feelings of pleasure that accompany
factors such as sex, love, and food.
The dopamine pleasure centre can be triggered artificially with illicit
drugs, alcohol, and nicotine, (known to increase aggression).
research examining the dopamine/aggression link is relatively sparse in
comparison to the serotonin literature base and is somewhat mixed, with
some linking both high and low levels of dopamine with aggression
this may be explained by one hypothesis that posits that individuals with
low levels of dopamine require greater levels of stimulation to experience
pleasure and are more likely to develop addictions to illicit drugs such as
cocaine that quickly increase dopamine levels and create an immediate
“high” but also have the side effect of increasing aggressive tendencies.
dopamine also regulates other neurotransmitters, including serotonin and
norepinephrine – dopamine exerts its influence indirectly via these
More research is needed to fully understand the role that dopamine plays
in antisocial behavior and aggression.
signals the body to react to short-term stress by increasing heart rate and
Limited research suggests that high levels of norepinephrine are correlated
supported by the finding that certain drugs (e.g., reserpine) that reduce
norepinephrine levels also reduce aggression
further investigation is needed to determine the exact role of
norepinephrine in antisocial behaviour.
6. Psychophysiology and Crime:
A psychophysiological theory uses physiology (e.g., low resting heart rate)
to explain psychological constructs (e.g., emotions, motivation, learning
These theories try to link measures of autonomic response (e.g., heart rate,
electrodermal activity/galvanic skin response/skin conductance) to various
measures along the antisocial spectrum.
Electrodermal activity (EDA) measures the amount of electrical current
between two points on the skin.
Increases in heart rate and EDA are related to general emotional responses
such as fear, anger, or anxiety
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Biological and Evolutionary Explanations
One of the most prominent psychophysiological theories is Gray’s arousal
model based largely on animal models of behavior
Hypothesizes that personality, learning, motivation, and emotional
responses are largely governed by two underlying biological systems of
autonomic arousal: the behavioural activation system (BAS) and the
behavioural inhibition system (BIS).
The BIS is conceptualized as an avoidance system responsible for
inhibiting or stopping behaviour in the face of punishment
The BAS is an approach or reward-seeking system that responds to
the BIS is linked to anxiety, the BAS is linked to impulsivity and
hypothesized that antisocial individuals have underactive behavioural
inhibition systems (are more fearless, less anxious, and less responsive to
this fearlessness and absence of anxiety manifests in autonomic responses
such as a low resting heart rate or low EDA.
Antisocial individuals have underactive behavioural activation systems
and are prone to sensation-seeking and impulsive tendencies that tend to
lead to antisocial behaviour one of the most comprehensive reviews of the
literature on psychophysiological tests of antisocial behaviour found that
there is a small effect for the relation between HR or EDA and various
conceptualizations of antisocial behaviour (e.g., aggression,
psychopathy/sociopathy, conduct problems); and this small effect is most
evident for psychopathy when EDA is used as the measure of autonomic
arousal (regardless of whether the paradigm involved “rest,” “task,” or
This review supports idea some antisocial individuals, (psychopathic),
show deficits in their behavioural inhibition system:: Did a faulty
behavioural inhibition system (BIS) lead to psychopathic tendencies? Or
did psychopathic tendencies lead to a faulty BIS?
In sum, while measures of autonomic arousal are small or possibly
moderate correlates of antisocial behaviour, the predictive and/or causal
status requires more research.
7. The Brain and Crime—Neuroimaging and Neuropsychology
The story of Phineas Gage was the first documented “natural experiment”
linking the brain to personality and behaviour.
Scientists have accumulated much knowledge about the brain and
antisocial behaviour since Gage’s unfortunate accident using brain
imaging studies and neuropsychology
Brain imaging (or “neuroimaging”) research examines the structural and
functional characteristics of the brain B
Brain structure is typically studied with magnetic resonance imaging
(MRI) and computed tomography (CT), while brain function is studied
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Biological and Evolutionary Explanations
through positron-emission tomography (PET) and single photon emission
computed tomography (SPECT)
Brain imaging studies are complex and diverse: involve assessing a small
number of “known” antisocial individuals to a comparison group earlier
studies compared the brain structures and/or functions of the two groups
more recent studies have compared brain function while the test subjects
were engaged in some cognitive activity
a recent review by Raine and Yang (2006) summarizes the results and
provides an integrated conceptual framework:
the study hypothesized that structural and/or functional damage to the
areas of the brain posited to be responsible for moral reasoning and
emotional regulation result in an “antisocial tendency.”
This antisocial tendency is thought to manifest in a variety of forms,
ranging from violent and sexual offending to psychopathic tendencies
and general criminality.
summary identified structural and/or functional deficits in four areas of
1. the frontal lobe—implicated in several higher order functions such
as cognitive reasoning, planning, sound judgment, patience, abstract
thought, moral reasoning, violence, and aggression regulation;
2. the temporal lobe—also implicated in the production and inhibition
of aggression (includes the amygdala, specifically involved in
emotional and fear situations; and the hippocampus, specifically
involved in memory, learning, and emotion regulation);
3. the parietal lobe—integrates sensory information related to
movement and space; and
4. the cingulated gyrus—the part of the brain that partially surrounds
the corpus callosum (the juncture in the brain that joins the left and
right hemispheres). Importantly, several of these structures are part
of the interconnected limbic system (i.e., the amygdala,
hippocampus, and cingulated gyrus)
In general, the limbic system is associated with emotion and the
autonomic expression of emotion—faster heartbeat, faster
respiration, trembling and sweating, and basic drives such as sex,
hunger, thirst, and the “fight or flight” response
1. structural and/or functional damage to the frontal lobe, specifically
the pre-frontal lobe, is the most replicated brain imaging abnormality
found in offenders to date.
2. the evidence is starting to suggest that structural/functional
impairments to parts of the limbic system (e.g., the amygdala and the
hippocampus) and the temporal lobe are also implicated in antisocial
3. there is no single brain structure that is ultimately necessary for the
development of antisocial behaviour; rather there are multiple
Copyright © 2011 Pearson Canada Inc. 24 Psychology of Criminal Behaviour: A Canadian Perspective Chapter 2: Theories of Crime:
Biological and Evolutionary Explanations
potential contenders and as the number of deficits increases, so does
the probability of antisocial behaviour.
neuropsychology studies brain function indirectly: a battery of
paper/pencil and/or motor tests designed to diagnose what part of the brain
Experts in the field of neuropsychology have studied whether deficits in
executive functioning (cognitive functioning involving future goal-
oriented behaviour, purposive attention, organizational skills, and
inhibitory control) are related to antisocial behaviour.
these functions have been associated with the frontal lobe, and perhaps
other components of the brain such as the connector pathways
a recent meta-analytic study: A robust effect was observed, indicating that
poor executive functioning is related to antisocial behaviour.
8. Other Biological Considerations—Pregnancy, Birth Complications, Toxins, and
Certain environmental insults change our biology in a manner that
heightens our propensity toward antisocial behaviour.
Inadequate prenatal (during pregnancy) conditions, perinatal (during birth)
complications, improper diet, and environmental toxins (e.g., lead) result
in changes to our biology that may in turn make us more likely to engage
in antisocial behaviour.
There is some evidence of a link between hypoglycemia (low blood
sugar—known to result in panic, irritability, nervousness, and aggression:
a double-blind study found that a program reducing sugar reduced
antisocial behaviour by 48 percent.
Researchers have also investigated the impact of certain neurotoxins,
namely lead, cadmium, and manganese, on brain development.
age 11, children with elevated lead levels exhibited significantly more
antisocial behaviour than their “normal lead level” peers
Manganese is known to impact serotonin and dopamine levels and to
somehow alter the levels of the monoamine oxidase (MAO) enzyme:
children with learning problems, attention deficits, and attention deficit
hyperactivity disorder (ADHD) had elevated levels of manganese.
diet-related research regarding the impact that vitamins, minerals, fat, fatty
acids, food additives, and even food allergies can have on antisocial
behaviour as well as the known precursors of antisocial behaviour—e.g.,
abnormal fetal development due to a variety of factors—maternal
smoking, drinking (Fetal Alcohol Spectrum Disorder), poor nutrition,
trauma experienced by the mother, and birth complications may
predispose an individual to antisocial behaviour.
hypoxia or lack of oxygen to the brain at birth can have a profound
impact on development, increasing the probability of learning
disabilities, impaired cognitive functioning, and intelligence:
Copyright © 2011 Pearson Canada Inc. 25 Psychology of Criminal Behaviour: A Canadian Perspective Chapter 2: Theories of Crime:
Biological and Evolutionary Explanations
Raine (1993) has hypothesized a direct link between birth
complications and adult violence.
research has shown two things
1. the environment (e.g., positive parenting) can reverse the potentially
deleterious effects associated with pregnancy and birth-related insults
and thus serve to protect individuals from their “biology” 2)
2. the environment (e.g., poor parenting) can aggravate “biological risk,”
such as children born with subtle neurological impairments (perhaps
due to birth complications)
it is important to underscore the complex interactions occurring not only
within the biological subsystems but also between them.
there are complex interactions occurring at the environmental level. e.g.,
the positive impact of “diet” on hyperactive children is magnified when
accompanied by a supportive home environment