AuthorCallender, John S.


Introduction 1121 I. Behavioral Genetics 1123 II. Brain Dysfunction and Crime 1136 III. Traumatization and Crime. 1143 IV. Criminal Justice and Paradigm Shift 1153 V. Imagining the Future 1160 Conclusion 1166 INTRODUCTION

If there are beings in the world whose acts shock all accepted prejudices, we must not preach at them or punish them ... because their bizarre tastes no more depend upon themselves than it depends on you whether you are witty or stupid, well made or hump-backed.... What would become of your laws, your morality, your religion, your gallows, your paradise, your gods, your hell, if it were shown that such and such fluids, such fibers, or a certain acridity in the blood, or in the animal spirts, alone suffice to make a man the object of your punishments or your rewards? (1) After all, I would probably never have been able to do anything with my magnanimity--neither to forgive, for my assailant may have slapped me because of the laws of nature, and one cannot forgive the laws of nature; nor to forget, for even if it were the laws of nature, it is insulting all the same. (2) De Sade and Dostoevsky were both writing before the advent of neuroscience. (3) These quotations illustrate that the application of neuroscience research to criminal behavior is casting a fresh light on, and throwing into relief, much older, philosophical questions about the nature of human actions. Are instances of criminal behavior to be understood in the way that we understand other events in the world, such as changes in the weather, or do they have a special quality that sets them apart? This special quality is usually understood in terms of concepts such as free will and responsibility. (4) The idea that we possess a capacity for free will and responsibility is an important element of our self-concept that imbues our lives with meaning. (5) The proposal that we are not creatures of God, with a God-given capacity for free will, but instead just puppets dancing on the strings of causal necessity, is a threat to this sense of exceptionalism. (6)

This threat extends beyond individual identity. There are major institutions in our societies that rest, at least implicitly, on foundations that are being challenged by neuroscience research.' These include most of the major religions and our systems of justice. (8)

There are also our intuitive, emotional responses to wrongdoing, especially when we, or those who are close to us, are the victim. (9) Nietzsche pointed out that "punishment developed as a retaliation absolutely independently of any preliminary hypothesis of the freedom or determination of the will." (10) In most societies, the state has taken over the role of punishment from individual victims and their families or clans. (11) In some cases, punishment of perpetrators may be an important element in helping victims recover from the traumatization of crime. (12) As illustrated by the quote from Dostoevsky, a scientific approach to crime may be seen as invalidating current rationales for blame and punishment. (13) The result is that all of the emotions generated by criminal acts could be denied any form of practical expression.

All of these questions lurk behind neuroscience approaches to criminality and create disquiet about where all of this is leading us. (14) Norms, practices, and institutions in criminal justice have evolved over centuries, and there are understandable anxieties about the potential for unintended consequences if these are undermined. (15)

The growth of neuroscience research in criminality and moral decision-making has been exponential in the past few decades. (16) It would take several large volumes to summarize this growth. In this Article, I will focus on three areas that seem to be of importance and will describe some research that illustrates how progress is being made. These are behavioral genetics, brain damage or dysfunction, and psychological traumatization. These each have impacts on individuals that increase the risks of criminality. (17) Furthermore, we often see a clustering of risk factors, and it is sometimes the combination of two or more of these factors that results in a criminal act rather than a single risk acting alone. (18)

I will conclude that the growth of research in neuroscience and criminality has taken us to a point at which we need a "Copernican revolution" in criminal justice. This would be a paradigm shift from a system based on prescientific beliefs, such as free will and good and evil, to one based on a scientific worldview. (19)


    Research into genetic factors in criminality has been carried out for many decades. (20) The two main sources of information have been twin and adoption studies. (21)

    In twin studies, the heritability of a characteristic is assessed by comparing concordance rates in monozygotic (MZ) and same-sex dizygotic (DZ) twins. (22) The concordance rate is the probability that both twins will possess a characteristic if one member of the twin pair does so. (23) Monozygotic twins are genetically identical. (24) Dizygotic twins have the same genetic similarities as non-twin siblings. (25) Differences in concordance rates can separate the impact of genetic and environmental factors in the causation of crime. (26) Twin studies of adult crime uniformly show higher concordance rates for MZ than DZ twins. (27) MZ concordance was on average around 50 percent, while DZ concordance was less than half of this. (28)

    In adoption studies, the prevalence of a characteristic under consideration is ascertained in a cohort of adoptees. (29) The relative influence of genetic and environmental factors is assessed by comparing the prevalence of the characteristic in the adoptive and biological families. (30) A landmark adoption study was carried out in Denmark by Mednick and others in 1984. (31) The researchers ascertained criminal convictions in adopted sons and their biological and adoptive parents. (32) If neither set of parents had a criminal record, the conviction rate in sons was 13.5 percent. (33) If the adoptive parents, but not the biological parents, had a criminal record, the conviction rate in sons was slightly higher at 14.7 percent. (34) If the biological parents alone had a criminal record, the conviction rate in the sons was significantly higher at 20 percent. (35) If both biological and adopted parents had been convicted, the rate in sons was higher still at 24.5 percent. (36) Moreover, there was a correlation between the number of offenses in the biological parents and the number in adoptees. (37)

    Both twin and adoption studies therefore point to genetic inheritance as one risk factor for crime. (38) But we need much more detail if this research is to be of practical use. We need a more precise description of what inherited characteristics increase the risk of criminality. We need to know which genes are important and how they produce effects on behavior. We need to know how these genes interact with each other and with environmental causes.

    One focus of research has been on callous-unemotional (CU) personality traits in children. (39) CU traits include diminished ability to feel guilt, failure to show emotions, lack of concern about school performance, and lack of concern for the feelings of others, (40) and are found in a group of children who are at high risk of developing persistent antisocial behavior. (41)

    Twin studies have shown that such traits are highly heritable. (42) In one study, the heritability of antisocial behavior was compared in children with high levels of CU traits and children with lower levels of CU traits. (43) Antisocial behavior in high-CU children was almost entirely influenced by genes with very little environmental impact. (44) In low-CU children, antisocial behavior was influenced by both genes and environment. (45) The high heritability of CU traits has been confirmed in more recent studies. (46) Takahashi and others assessed CU traits in twin pairs at ages seven, nine, twelve, and sixteen. (47) The heritability of CU traits at baseline was high at 76.5 percent. (48) There was an independent genetic influence on the developmental course of these traits. (49) It was also clear that environmental influences had a major role on whether these traits were maintained, increased over time, or decreased. (50)

    One environmental factor that may be important is quality of parenting. (51) Waller and others studied the relationship between parental harshness and warmth with differences in CU traits and aggression in MZ twin pairs. (52) Parental harshness was related to both childhood aggression and CU traits. (53) Low parental warmth was related to CU traits but not aggression. (54) This raises the possibility that intervention in families aimed at improving parenting practices might lower the emergence of aggression and CU traits in children.

    A major development over the past twenty years has been research into gene-environment interactions. There are six recognized "nonspecific neurotransmitter projection systems each having its origin in nuclei located in the brainstem." (55) These are specified by the neurotransmitter secreted at the axon terminals (dopamine, serotonin, noradrenaline (norepinephrine), adrenaline (epinephrine), histamine, and acetylcholine). (56) These are said to be nonspecific because they have modulating effects on widely distributed areas of the brain. (57) Abnormalities in these systems have been implicated in the causation of illnesses such as schizophrenia, affective disorders, obsessive-compulsive disorder, and others. (58) The enzyme monoamine oxidase A (MAOA) plays a major role in the metabolism of neurotransmitters such as serotonin, noradrenaline, and dopamine, thus rendering them inactive. (59)

    The significance of this enzyme in the study of crime first emerged in 1993, when Brunner and others described a family in which several males were affected by...

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