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Chapter 2

PSYC39 - chapter 2.docx

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David Nussbaum

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PSYC39 – Ch.2 Theories of Crime: Biological and Evolutionary Explanations Introduction - Focuses on biological and evolutionary explanations for antisocial behaviour, crime and related phenomena. - Biological explanations are varied: genetics exemplified by twin and adoption studies, brain neurochemistry and importance of diet. What makes a strong theory? - Parsimonious - Clearly identifies the causal mechanisms and corresponding mediators and moderators underlying the phenomenon of interest - Testable and falsifiable via hypotheses and predictions - Based on empirical data and is modified in response to new data - Possesses interdisciplinary compatibility - Respects gender, ethnicity and culture Background Historical Context - Franz Gall (1758-1828) was the father of phrenology – a theoretical perspective positing that there is a relationship between the shape and size of a person’s head and his/her personality, mental ability and behaviours. - Like most phrenology-oriented researchers at the time, Spurzheim (student of Gall) failed to include a comparison group, e.g. women who had not killed their children.  the ‘science’ of phrenology eventually died out. - Cesare Lombroso (1835-1909) was the father of criminology. He took Gall’s work one step further and began comparing criminals to ‘normal’ segments of the population. - Lombroso proposed that criminals possess distinctive physical features and referred to the features as atavisms. e.g. sloping foreheads and twisted lips often not observed in his normal subjects. He suggested that criminals were evolutionary throwbacks who had more in common with Neanderthals than modern-day man. - Charles Darwin posited that humans had evolved from ancestral species via the mechanisms of natural selection. (Published on the1st volume of The Criminal Man). But others began to misuse his work - Francis Galton founded eugenics – the theory that was ultimately responsible for the forced sterilization (or worse) of thousands of individuals deemed ‘unfit’ to reproduce in the US during the early part of the 20 century, and for the atrocities that occurred under Hilter’s regime – forced abortion, sterilization and death camps. (The science of improving a human population by controlled breeding to increase the occurrence of desirable heritable characteristics. Developed largely by Francis Galton as a method of improving the human race.) - Anderson (2007) demonstrates that the study of biology and evolution has advanced considerably since Darwin and Lombroso. It is becoming increasingly clear that biology is not destiny Researching biological explanations of crime - Researchers often define crime using current legal definitions and examine whether biological factors correlate or predict official criminal offending in the form of arrests or convictions. - Targets of study are varied. E.g. some focusing on males; others on females, children, adolescents, or specific groups of offenders such as violent of sexual. - Research methods and participant pools are vast and complex. Genetics and Crime – Twins, adoption, and molecular genetics - Behavioural genetics (relies heavily on the study of twins and adoptions) can help separate genetic from environmental influences - the percentage of DNA that humans collectively share, 99%, is fixed, accounting for our basic similarities. Behavioural genetics focuses on the remaining 1% of the variance that is free to vary. Twin Studies - Monozygotic (MZ) twins (identical) are genetically identical; Dizygotic (DZ) twins (fraternal) sharing on average only 50% of that free-to-vary- 1%. - In the earliest forms of twin studies, research would identify sample of MZ and DZ twins, both raised by their respective biological families and obtain some estimate of criminal behavioiur via self-report or official records. Concordance rates would be calculated separately for MZ and DZ twins then compared. 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 - descriptive statistics that represents the proportion of phenotypic variance in a given behvaiour, e.g. criminal, in a sample that can be attributed to genetic variation among individual. - Recently, more complex statistical appraches such as biometic modeling have been used to estimate heritability coefficient. - Biometic modeling – permit the estimation of two types of environmental factors: shared environmental factors and non-shared environmental factors (exposure to different peer groups or differential treatment by parents).  contrary to popular belief that genetics studies are just as much about genes as they are about environment - Common criticism against twin study: may overestimate (sometimes underestimate) the genetic contribution for several reasons. - 1. Parents are arguably more likely to provide similar environments for MZ twins than DZ counterparts, thus artificially inflating the genetic contribution (this problem us remedied by ‘natural experiments’, where MZ twins have been separated at birth and reared apart) - 2. Heritability estimates for MZ twins may be confounded by prenatal favtors = not necessarily genetic e.g. MZ twins usually have one placenta and DZ twins usually have two separate placentas, thereby introducing a potential biological difference that is not necessarily genetic. Adoption Studies - two forms: parent-offspring adoption studies & sibling-offspring adoption studies. - Parent-offspring paradigm: concordance rates/correlations between adoptive parents and adoptees’ antisocial behaviour are compared to that between biological parents and adoptees. if concordance rates are higher for biological parents and adopted offspring, genetic contributions to antisocial behaviour are inferred. - Related variation of the design is the cross-fostering paradigm. Adopted children have biological parents who were criminal/non-criminal OR adoptive parents who were criminal/non-criminal - Sibling-offspring paradigm, concordance rates between adoptive siblings are compared with that between biological siblings - Mednick et all (1984) performed a particularly strong adoption study of 14427 non-familial adoptions in Demark (1927-47). Ascending order of criminality of the offspring BP and AP were not criminal AP ys, BP no BP ys, AP no, BP and AP YES.  Results show that both genetics and environment both contribute to variance in antisocial behaviour - Limitations of adoption studies: 1. generalizability problem given that adoptees have higher rates of antisocial beh relative to the rest of the population 2. The environments of adopted offspring tend to be more advantageous relative to the general population. Which potentially reducing shared environmental effects due to restricted range - Research increasingly show that the gene-crime link is most likely not a direct conduit, but a function of the meditational effects of inherited characteristic that predispose an individual to antisocial behaviour, e.g. lower intelligence, impulsivity, ADHD. -  antisociality often results from a series of complex interactions between numerous factors. Molecular Genetics Research - Caspi and colleagues (2002) published a study demonstrating an interaction between a specific gene and a well-known risk factor – childhood maltreatment. The study was epidemiological in nature. They studied how the low-activity version of monoamine oxidase A (MAOA) may or may not intensity the effects of childhood maltreatment. - The MAOA gene is responsible for encoding the MAOA enzyme, which in turn is responsible for metabolizing or breaking down key brain neurotransmitters such as norepinephrine, serotonin, and dopamine. All of which have been implicated in aggression and various forms of antisocial behaviour - Two existing versions of the MAOA gene = low activity and high activity, are the result of polymorphism - Result: over 80% of youth classified as having low MAOA activity and as being severely maltreated were classified as conduct disordered; only 40% with high MAOA activity plus severe maltreatment were conduct disordered.  while maltreatment by itself had deleterious effects, its effects were exacerbated by the presence of a low-activity MAOA gene. - Foley et all (2004), Frazzetto et al. (2007) replicated Caspi et al’s findings as well. - Increasing evidence show that the low-activity version of the MAOA gene, sometimes dubbed the ‘warrior gene’ played a significant role in the expression of antisocial behaviour, particularly aggression and violence. * the low activity MAOA gene only expresses itself in the presence of certain environmental cues, e.g. childhood abuse or provocation. Neurochemistry and Crime – Hormones and Neurotransmitters Hormones and Crime - the endocrine system governs more than 50 hormones in the human body. Hormones are released into our bodily fluids (typically via the bloodstream) by nine primary glands. - Hormones not only regulate metabolism, growth, and development and impact behaviour - Testosterone is one particular hormone implicated in criminal behavior, e.g. violence and aggression. Studies found that younger males have higher level of testosterone; and testosterone levels fluctuate more in the morning and stabilizes in the afternoon and evening, thus higher level as well. - In physical and chemical castration studies shown that sexual re- offending is reduced in offenders. Suggesting the relationship between testosterone and sexual aggression may be more than correlational. - Premenstrual syndrome (PMS) has been used (albeit rarely) successfully as a legal defense in Britain and the US, and as a mitigating factor in Canada. PMS – related to aggression (p.40 for more details) Neurotransmitters and Crime - Like hormones, neurotransmitters are chemical messengers that operate in the brain. Neurotransmitters are the messengers of the nervous system. - Three neurotransmitters in particular have been studied in relation to crime: serotonin, dopamine, and norepinephrine - The neurotransmitter sertotonin, or hydroxytryptamine (5-HT) plays an important role in behavioural inhibition and mood regulation. It is produced from an essential amino acid, tryptophan. - Research has shown that there is a link between a malfunctioning serotonin system and impulsivity, irritability and aggression (directed at self or others). Malfunctioning serotonin systems: low levels of serotonin, low levels of its precursors such as tryptophan, low levels of its metabolites (once neurotransmitter has completed its job it breaks down into metabolites), and faulty serotonin receptor sites on the postsynaptic neuron. - Moore, Scarpa and Raine’s (2002) meta-analytic review of 16 studies, on average serotonin levels (as measured via cerebro-spinal fluid, CFS serotonin metabolites) were substantially lower among antisocial individuals than non-antisocial individuals. the effect was even more pronounced for individuals under the age of 30. - In Moffitt et al. (1998)’s epidemiological research design, results show a moderate (positive) correlation between blood serotonin levels and violent criminal behaviour for men but not women.  there is a correlational link between a malfunctioning serotonin system and aggression. - Studies that artificially manipulate the level of tryptophan and then examine its impact on aggression in a lab setting suggest a causal link. Other studies suggest that serotonin may exert its influence indirectly on aggression through the mediator of impulsivity or perhaps negative mood. Potential treatment implications suggest that changes in diet could reduce aggression! Anyhow, these researches remain preliminary. - Dopamine release causes feelings of pleasure that accompany factors like sex, love and food. - More research is needed to fully understand the role that dopamine plays in antisocial behaviour, particularly aggression. it is possible that dopamine exerts its influence indirectly via other neurotransmitters, e.g. serotonin and norepinephrine as dopamine also regulates them. Another hypothese is that individuals with low level of dopamine require greater levels of stimulation to experience pleasure – more likely to develop addictions to illicit drugs like cocaine that quickly increase dopamine levels and create an immediate high, but also have the side effect of increasing aggressive tendencies. - Norepinephrine signals the body to react to short-term stress by increasing heart rate and blood pressure. - Limited research suggests that high levels of norepinephrine are correlated with aggression.  further investigation is needed to determine the exact role of norepinephrine in antisocial behaviour. Psychophysiology and Crime - Psychophysiology theory uses physiology (low resting heart rate) to explain psychological (emotion, motivation, learning) constructs. - Some psychophysiological theories try to link measures of autonomic response (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 2 points on the skin. - Gray’s arousal model (based largely on animal modStuels of behaviour) hypothesized that personality, learning, motivation, and emotional response are largely governed by two underlying biological systems of autonomic arousal: the behavioural activation system (BAS) and the behavioural inhibition system (BIS). - BIS – an
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