Exploring Human Aggression through Animal Behavior, Genetics, Neuroscience, Psychology, and Neuroethics
Lily Spagnola, Cedar Crest College
Abstract: Aggression is a complex phenomenon that has profound implications for individuals and society and has been the subject of extensive research across various disciplines. An interdisciplinary approach is used to examine aggression through the lens of behavioral studies, genetics, neuroscience, and psychology to gain a deeper understanding of the healthcare implications for individuals as well as strategies aimed at protecting public well-being. Behavioral studies, which utilize both animal and human models, investigate the environmental factors that play a role in promoting aggressive behavior, including social contexts, stressors, and learned behaviors. Genetics also plays a significant role, with certain gene variations and genetic markers being associated with aggressive tendencies, highlighting the role of heredity in aggression. Neuroscience gives valuable insight into the neural mechanisms that underly aggressive actions. Specifically, the crucial role of certain brain regions, neurotransmitters, and hormonal influences will be reviewed. Advancements in understanding the biology of aggression have led to a complex array of ethical questions surrounding societal responses to aggressive behavior. For example, the treatment of individuals with a predisposition to aggression in the legal system has not been codified but is beginning to be raised in trials. By understanding the multifaceted nature of aggression, lawmakers can develop better policies that meaningfully address this type of behavior. Overall, this paper highlights the growing emphasis on both biological and environmental factors when it comes to the root of aggressive behavior, as well as the importance of collaboration among disciplines when creating policies to address criminality.
Introduction
Human behavior is the intricate way individuals express themselves in differing social contexts. The study of these behaviors gives valuable insight into the human condition. One such behavior is aggression, a multifaceted behavior that can have serious implications for individuals and society overall. When studying aggressiveness and its cause, researchers often look through the lenses of biology, environment, and society to create a complete picture. Beginning with the use of animal models, the genes and neurotransmitters involved in aggressive behavior have begun to be uncovered. In combination with research focused on environmental and societal factors, it is found that they all play an equal role in aggressive tendencies. This becomes increasingly important in criminal cases, as it draws the question as to whether individuals should be held responsible for behavior that may be out of their control.
The Biopsychosocial Theory
One of the ways to study aggression is by employing George Engel’s biopsychosocial theory, which can be broken into three parts: biological, psychological, and social. The biological part of his theory focuses on the physiological factors related to health and disease, including brain structure, neurochemistry, and genetic predisposition (Engel 1977). The psychological aspect then accounts for psychosomatic and developmental experiences that could affect a person’s mental and emotional health (Engel 1977). For example, studies on inmates have found that neuroticism, trait anger, and agreeableness lead to a higher predisposition to state anger and aggression (Hornsveld and Kraaimaat 2022). A person’s executive functioning is also key to regulating emotions such as anger and aggression (Shumlich et al. 2018). Both forensic psychiatric patients and correctional offenders have been found to have significant executive dysfunction, which can manifest itself in socially inappropriate behavior, for example.
Equally as important are the social contributors to a person’s life, such as social relationships, environment, and romantic relationships, which can significantly impact an individual’s cognitive development and overall functioning (Sharma and Marimuthu 2014). For example, social status is often associated with reactive aggression or an individual’s response to a social threat or frustration (Bertsch et al. 2020). Individuals who grow up in lower socioeconomic classes interpret seemingly ambiguous stimuli as threatening, (Chen and Matthews 2003). This may be due to greater exposure to uncontrollable stressors such as violence, parental separation, crowding, and food insecurity (Evans 2004).
When viewed from a biological perspective, exposure to violence is significantly associated with an increase in amygdala response when exposed to angry faces (White et al. 2019), and factors other than violence exposure, such as parental separation/family conflict, crowding, and pollutant exposure, which are more common in areas of lower socioeconomic status, can cue this amygdala reactivity. This suggests that an individual's tendency to act aggressively is shaped not just by their underlying biology, but also by the interactions of psychological and social elements. Although this theory has three seemingly distinct lenses, it emphasizes the interplay of all these factors in their contributions to a certain behavior, in this case, aggression. Thus, the biological, psychological, and social influences in a person’s life must be considered when thinking about aggression.
Biology
Aggression is a complex behavior that is heavily influenced by various biological factors. More specifically, impulsive aggression is the inability to regulate affect and aggressive impulses (Seo et al. 2008). At the neurological level, the regulation of neurotransmitters such as dopamine, serotonin, and norepinephrine play a crucial role in modulating aggressive impulses and behaviors.
Dopamine and serotonin have been thought to contribute to antisocial behavior, which is associated with criminal behavior (Paul 2020). Dopamine regulates mood; specifically, the motivation and reward pathway. Aggression is considered a rewarding experience (Chester et al. 2017). The connection between dopamine and aggression can differ depending on the brain region affected. Both lower levels of dopamine and genetic defects in the dopaminergic receptor DRD2 in brain areas such as the nucleus accumbens and striatum put an individual at risk of impulsivity and subsequent violence, as they are more likely to be motivated to act aggressively to experience pleasure. However, increased dopamine projected by dopaminergic neurons in the ventral tegmental area (VTA) to the lateral septum is also linked to aggression (Mahadevia et al. 2021). Serotonin has an inhibitory effect on the brain and is involved in regulating emotion and behavior, including aggression (Seo et al. 2008). Dysregulation of serotonin systems in the brain is then associated with aggressive behavior. Specifically, low levels of serotonin have been linked with such behavior. The dopaminergic and serotonergic systems have been found to interact with one another, with dopamine promoting appetitive behaviors, and serotonin preventing such behaviors. The interaction of these two systems may be related to the mechanisms underlying impulsive aggression. Dopamine neurons are modulated by serotonin and receive strong projections from their neurons. Therefore, there is a functional modulation of serotonin over dopamine activities in the nervous system. A decrease in serotonin in the brain may thereby cause an increase in activity in the dopaminergic system, specifically in prefrontal regions, thus promoting impulsive behavior.
Norepinephrine has also been implicated in antisocial and criminal behavior (Paul 2020). The epinephrine/norepinephrine system facilitates autonomic nervous system activity and fight-or-flight reactions and generally functions as a central arousal system. The relationship between norepinephrine and maladaptive behaviors may be curvilinear; high and low levels can increase problem behavior. For example, there is hyperactivation of norepinephrine in people who face acute traumatic stress, correlating to an increase in maladaptive behavior (Goddard et al. 2010). Lower levels of this neurotransmitter may be linked to antisocial behavior (Wright and Newsome 2014).
GABA is another neurotransmitter that regulates the nervous system and cognitive functioning (Wright and Newsome 2014). It balances excitation in the brain by inducing relaxation and sleep. Reduced levels of GABA can lead to increases in irritability, anxiety, and violent behavior. In contrast, excessive levels of GABA depress cognitive functioning. Alcohol and the date rape drug gamma hydroxybutyrate (GHB) have effects on the brain like excessive amounts of GABA; body senses are inhibited, making it difficult to fully understand the immediate environment.
Additionally, neuropeptides and specific brain regions have been identified as key players in the biological underpinnings of aggression. It is thought that the neural circuits that control aggression are also regulated by neuropeptides, which are small proteins produced by neurons (Asahina et al. 2014). They coexist either with each other or with other neurotransmitters in a single neuron (Merighi 2017). Neuropeptides act on G-protein coupled receptors (GPCRs) and play a role in increasing and decreasing synaptic transmission. This dysfunction can result in excess or lack of neurotransmitters in the synaptic cleft, meaning the wrong amount of neurotransmitter is delivered to the postsynaptic neuron (Palavicino-Maggio and Sengupta 2022). As previously mentioned, too little or too much neurotransmitter can result in aggressiveness.
The biological causes of aggression have been studied heavily in animal models. The species Drosophila melanogaster, or the common fruit fly, is frequently used as a model for aggression because it is easily genetically manipulated and has the potential of individual neurons being identified that control specific behaviors. D. melanogaster displays sexually dimorphic aggressive fighting behaviors (Chan and Kravitz 2007). In this species, it is known that this sex difference-related aggression is caused by the fruitless (fru) gene, which regulates sexual differentiation in the brain.
Male fruit flies have a small cluster of sexually dimorphic FruM+ neurons, which express the neuropeptide tachykinin (Tk) (Asahina et al. 2014). When these neurons are activated or silenced, there is an increase or decrease, respectively, in intermale aggression. However, this does not affect male-female courtship behavior. When male and female fighting patterns were transferred to the opposite sex, through the masculinization or feminization of specific neuron populations, it was determined that there is a strong association between FruM+-expressing cells and aggression (Chan and Kravitz 2007).
Substance P (SP), a member of the tachykinin family of peptides, has also been identified as a crucial neuropeptide involved with the induction and regulation of aggressive behavior (Katsouni et al. 2009). One brain region known to utilize SP is the medial nucleus of the amygdala, which plays a role in emotional behavior responses. SP has a high affinity for the neurokinin-1 receptors, NK1. When studied in animals, it has been seen that SP activates hypothalamic NK1 receptors, inducing animal rage and aggressive behavior, emphasizing the complex neurochemical mechanisms underlying aggressive behavior.
Aggression can manifest itself in a series of different behaviors across species and is controlled by different brain areas. For example, defensive rage in cats is a response to threatening stimuli (Gregg and Siegel 2003). Physiological manifestations of defensive rage include pupil dilation, increased heart rate, baring of the teeth and claws, and aggressive pawstrike, mediated by a pathway between the periaqueductal gray and medial hypothalamus. On the other hand, predatory attack behavior includes quiet stalking and attacking of a prey object and is mediated by the lateral hypothalamus. Experimental manipulations that produce one of these behaviors inhibit the other, indicating that these behaviors work together in a neural circuit dependent on the GABAergic systems within the hypothalamus.
When cats were injected with the NK1 antagonist CP-96,345, a drug that blocks NK1 receptors, decreases in medial amygdaloid-induced defensive rage were observed (Shaikh et al. 1993). This supports the notion that the medial amygdala facilitates defensive rage through an SP mechanism in the medial hypothalamus. Giving felines microinjections of the NK1 agonist GR73632, a drug that activates NK1 receptors, into the dorsal periaqueductal gray facilitated a dose-dependent defensive rage, as well as spontaneous hissing, showing not only the significance of SP in regulating aggressive behavior but also the importance of NK1 receptors (Gregg and Siegel 2003).
A similar trend has been observed in rats. Rats have a brain region called the hypothalamic attack area, which is the only region where electrical and neurochemical stimulation can reliably cause biting attacks (Halasz et al. 2009). It is also known to express NK1 tachykinin receptors. Using SP that had been conjugated to saporin, a ribosome-inactivating protein, neurons that express NK receptors were lesioned. This subsequent decrease in NK1 receptors significantly decreased the number of hard bites performed by the rats, indicating NK1 receptor neurons from the hypothalamic attack area are directly involved in violent forms of attack.
Research has also been conducted on many genes to explore connections between genetics and aggression (Richter et al. 2011). Although more progress has been made using animal models, examples have also been found in humans. For instance, A-kinase-anchoring protein 5 (AKAP5) is associated with individual differences in both aggressive behavior and anger expression in humans (Richter et al. 2011). A-kinase-anchoring proteins are a group of proteins that bind to protein kinase A (PKA) and help regulate cell signaling. AKAP5 is a specific post-synaptic multi-adaptor molecule that binds to GPCRs, protein kinases A and C, and other intracellular signaling molecules. The human version of AKAP5 has a specific functional genetic polymorphism, or gene sequence variation, that causes the substitution of proline to leucine at position 100 (Pro100Leu). This substitution is thought to influence protein folding and curvature, and ultimately human aggression and aggression-related emotion due to its role in modulating neuronal activity. Individuals who carry the leucine allele rather than the more common proline allele scored significantly lower in the physical aggression domain of the Buss and Perry Aggression Questionnaire and higher in the anger control dimension of the state-trait anger expression inventory, which are both personality questionnaires that assess anger and aggressive behavior through a variety of factors.
The same study then used functional magnetic resonance imaging (fMRI), to reveal the AKAP5 Pro100Leu substitution is crucial in modulating human emotional processing and executive functions (Richter et al. 2011). Those carrying the Leu allele had increased activation of their anterior cingulate cortex when exposed to emotional interference, causing shorter reaction times, possibly related to their stronger ability to control emotional interference. Conversely, those with the Pro allele had increased orbitofrontal cortex activation during emotional interference, and thus no clear behavioral advantages.
Another gene more commonly understood to be linked to aggression in humans is monoamine oxidase A (MAOA), whose protein product helps break down neurotransmitters such as dopamine, norepinephrine, and serotonin (McDermott et al. 2009). MAOA also experiences polymorphisms, the most prevalent being low-activity MAOA (MAOA-L) and high-activity MAOA (MAOA-H). Specifically, MAOA-L has been thought to cause aggressive behavior.
As previously mentioned, MAOA is responsible for breaking down neurotransmitters. When neurotransmitters are not broken down, they will continue to stimulate the receptor. Individuals with MAOA-L have higher levels of serotonin and norepinephrine in their brains due to this lack of neurotransmitter breakdown (Godar et al. 2014). These higher levels of norepinephrine may contribute to aggressive behavior, while treatment with fluoxetine, a drug used to prevent serotonin reuptake, or reabsorption, into the neuron, caused a decrease in aggressiveness.
In humans, it is believed that these MAOA polymorphisms can help mediate the likelihood of early life trauma to lead to violent behavior as an adult. It has been found that children with MAOA-L who suffer abuse are more likely to develop antisocial issues as adults (Stetler et al. 2014). Fergusson et al. (2011) observed males at birth, 4 months, 1 year, annually to age 16 years, then at 18, 21, 25, and 30 years old and obtained blood samples from participants between ages 28 and 30, screening for MAOA activity and labeling them as having either MAOA-H or MAOA-L. History of exposure to abuse during childhood was taken and categorized as childhood sexual abuse, childhood physical abuse, exposure to significant childhood sexual or physical abuse, and interparental violence. Participants were also assessed for antisocial behavior, which included self-reported and officially recorded property or violence offenses, conduct problems, and hostility. Sociodemographic background, family functioning, and other individual factors were also considered. Overall, it was concluded that there is a stable interaction between genes and the environment, regarding MAOA, abuse exposure, and antisocial behavior across a lifetime. Those with the MAOA-L genotype and exposed to maltreatment during childhood were significantly more likely to report antisocial behaviors.
Violent crime was highly associated with individuals with the MAOA-L genotype when looking at male convicts in a Kansas correctional facility (Stetler et al. 2014). Interestingly, this finding was very significant with Caucasian individuals, while only slightly significant with African American individuals.
Likewise, research done by McDermott et al. (2009) investigated MAOA allele expression variance as it relates to differences in engagement of aggression. Individuals participated in an experimental game and were told a portion of their earnings were taken by an anonymous person. They were then allowed to punish said player by forcing them to eat hot sauce, or they could trade in the hot sauce for money. MAOA-L individuals were more likely to administer the punishment when more of their money was taken away compared to MAOA-H individuals.
It is evident that genetics plays a crucial and complex role in a human’s likelihood to engage in aggressive behavior. Understanding these genetic factors is essential to our comprehension of human behavior. However, these genetic factors do not work alone. In conjunction with external factors, such as environmental conditions including upbringing, social interactions, and cultural influences, a person’s tendency to become aggressive can be significantly influenced and shaped.
Psychology
In early childhood, humans experience major cognitive and social-emotional development (Young and Keenan 2022). These experiences, such as finding a new sense of self-awareness, more sophisticated language, and verbal communication skills, as well as goal-directed behavior, cause a child to strive for more independence. At the same time, parents typically begin placing more rules and limitations on their children in response to this newfound independence to prepare them to integrate and socialize within society. Conflict between the child and the parent causes the child to express frustration in response to this increase in limitations, which sometimes manifests in aggressive behavior. Violent behavior in children can range from explosive tantrums to physical aggression. Some children may also begin using weapons, engage in animal cruelty, or intentionally destroy property, which are symptoms of more serious behavioral disorders such as conduct disorder (Frick 2016). Aggressive behavior and tendencies can also be affected by situational triggers and experiences, such as exposure to violence, use of illicit substances, being the victim of bullying, and a combination of stressful familial socioeconomic factors. In typically developing children, aggressive behavior gradually declines within the first five years of life, as they learn to replace these behaviors with prosocial skills taught in early childhood, like communication as a form of conflict resolution and the ability to express one’s needs (Young and Keenan 2022).
One of the most well-known child aggression studies is Albert Bandura’s Bobo doll experiment (Bandura 1965). Preschoolers were divided into three groups and observed either aggressive behavior models, nonaggressive behavior models, or no behavior models. The behavioral models were adult researchers who interacted with “Bobo dolls,”: inflatable plastic toys painted like clowns. Aggressive models abused the doll both physically and verbally, whereas the nonaggressive models would ignore the doll and engage in another activity. In the next phase, the children were then subjected to aggression arousal, by being told they could not play with desired toys before being put in a room with the Bobo doll along with aggressive and nonaggressive toys. After 20 minutes, children exposed to the aggressive behavioral model displayed significantly higher aggression scores compared to the other two groups.
Similar studies have also observed the possible long-term potentiation of aggressive behavior in children. For example, intense anger responses in toddlers after exposure to a frustrating task is associated with higher aggression levels later in childhood (Liu et al. 2022). Toddlers who responded to an arm-restraint task by attempting to escape and support-seeking behaviors (looking at a parent) had an increase in anger expression, while those who responded with distraction (looking away) or focus-on-restraint behaviors (looking at a toy) did not show any changes in anger. This is consistent with findings that show children who engage in support-seeking behaviors when met with an unresponsive parent, experience subsequent increased anger expression. When the same children were observed at 4.5 years, those with high aggression as toddlers again exhibited higher aggression, and vice versa.
Characteristically across all cultures, aggression is a highly masculine-typed behavior, being viewed as more “appropriate” for males. Parents are typically more accepting of anger displayed by sons rather than daughters (Eliot 2021). This acceptance can be conveyed in different manners. For example, mothers often accept tantrums from sons rather than daughters (Potegal and Archer 2004). Fathers also contribute to this conditioning, as they are more likely to soothe their daughters and reprimand their sons for expressing fear or sadness. Despite both male and female children expressing an equal likelihood of experiencing frustration and anger early on in life, female children have a more rapid decline in their physical aggression (Eliot 2021).
Interestingly, the Bobo doll experiment also suggested sex-related differences regarding aggression expression (Bandura 1965). The original three groups were divided into six subgroups by gender, with half of the groups observing a same-sex behavior model and the other half observing an opposite-sex behavior model. Male subjects were more likely to imitate physical aggression than female subjects. Both female and male subjects were also more prone to imitate physical aggression seen by the male behavioral models compared to the female models. However, children were more imitative of verbal aggression from a same-sex model.
Adoption studies have commonly been used to study the connection between genes and the environment related to criminality; specifically, the implications of rearing environments. A study in Denmark found sons who had been adopted were more likely to have a court conviction if their biological parent had also had a court conviction (Mednick et al. 1984). Twenty percent of adoptees had one or more convictions if their biological parent also had one or more convictions, but their adoptive parent was law-abiding. If only the adoptive parent had been convicted, only 14.7 percent of adoptees also had a conviction. If neither the adoptive parent nor the biological parent had been previously convicted, only 13.5 percent of sons had convictions. This highlights the important role genetics plays in criminality, compared to environment. Despite children being raised in a positive living environment, in this case, genetic components seem to be more crucial regarding the likelihood of being a criminal later in life.
Expressing aggression is not always atypical; it is a normal part of childhood development (Aggression n.d.). Children often show anger when faced with frustrating stimuli such as being left out, needing attention, or having a toy taken. However, they are not born with the ability to regulate these emotions and are unaware of how this behavior can affect those around them. The parent or adult caregiver must intervene to teach the child healthy ways to express these feelings, helping foster emotional intelligence and self-regulation skills, such as talking through their emotions, rather than acting on them. Guiding the child to communicate their frustrations allows them to redirect their aggressive tendencies into more positive behaviors, benefiting the child’s social-emotional development and creating a more harmonious environment for the family.
Instead of considering outbursts during childhood as problematic, it is crucial to view them as opportunities to teach the child about appropriate emotional expression, so they can become well-adjusted individuals who can navigate challenging situations without resorting to aggression. Concern should begin if these interventions are not well received, and the behavior continues into late adolescence and early teenage years.
Viewpoints on aggression can also vary across cultures and countries. For example, Canada, Australia, and New Zealand are much less violent than the United States, while Africa and Asia are much more violent (Jhangiani and Tarry 2022). Children from the Middle East are less accepting of aggression than children from the United States (Huesmann and Skoric 1999). Living in a certain environment can also influence an individual’s behavior later on. For instance, Hispanic children who had been in the US were more accepting of aggressive behavior than those who had not been in the US as long (Guerra et al. 1993).
These differences can even be found between places seemingly closely related such as two neighboring states. A cultural norm prevalent in southern states is the culture of honor, which condones and encourages an individual to respond to an insult with aggression (Jhangiani and Tarry 2022). This norm is thought to be linked to the significantly higher homicide rate in southern and western states in America (Cohen et al. 1996). In studying this culture of honor in white males, it was found that individuals from the South, compared to the North, were more likely to perceive being bumped into as a threat to their masculinity, exhibiting greater physiological signs of being upset, such as high testosterone levels, and engage in more aggressive behavior, highlighting how aggression perception can vary even within a single country.
Neuroethics
It is unclear what the exact cause of criminal behavior is. However, the link between genes and violent behavior cannot be simply defined as a causal relationship (Forzano et al. 2010). There are a multitude of other factors, as previously noted, that must also be present for a person to act on their instincts. Since these elements work in conjunction, it is difficult to use just one to predict behavior. Although someone may have a certain genetic predisposition to act in a certain way, this does not necessarily mean they will become a criminal. A positive living environment, for example, may minimize the effects of genetic susceptibility, just as a negative living environment may trigger it, highlighting the relationship between genes and the environment (Tehrani and Mednick 2000).
Currently, much focus is on social factors such as socioeconomic status and home life. However, as more evidence is being made for genetic factors' role in aggression, there is increasing debate as to whether genetic predisposition is a reputable piece of evidence in a court of law. Using genetic disposition and information causes a few ethical concerns when it comes to the legal system, as well as to society. Neuroethics is a field that studies the ethical and legal implications of questions related to neuroscience and the mind.
A single “criminal gene” has not yet been identified, but multiple genes have been associated with aggression and therefore correlated to criminal behavior. Despite violent offenders sharing similar genetics, there is no strong evidence to implicate a singular gene in causing crime (Anand 2023). Instead, criminal behavior is influenced by a combination of gene interactions and behavioral characteristics, including psychopathy, neuroticism, impulsivity, manipulation, and a limited capacity for empathy. Therefore, behaviors such as impulsivity and sensation-seeking, combined with genetic factors, are more likely to be contributors of criminalistic tendencies, rather than one of these alone (Tehrani and Mednick 2000).
While certain behavioral characteristics make a person more susceptible to committing violence, those who carry the genes responsible for these traits are the ones who are likely to display this violent behavior (Anand 2023). However, there is no scientific support that these genetic variants prevent a person from controlling their aggressive behavior and acting socially appropriate (Forzano et al. 2010). Thus again, it is unfair to causally link a certain genetic predisposition to criminality. Someone possessing a specific “aggressive gene” variant may never act criminally in their life, making it difficult to determine when a safe assumption can be made to use this type of evidence to indict someone as not responsible for their actions.
Aspinwall et al. (2012) were one of the first groups of researchers to look at how judges view this type of biological evidence more directly and systematically. Judges were presented with a hypothetical murder case and asked the sentence the hypothetical suspect, Jonathan Donahue, should receive given a subset of evidence. All judges were given an “expert evaluation” from a psychiatrist, indicating Donahue had been diagnosed as a psychopath. Some judges also received evidence that detailed testimony from a neurobiologist, giving genetic and neurobiological explanations for Donahue’s development of psychopathy. Overall, judges who had not been given the additional evidence gave Donahue an average sentence of 13.93 years, while those who received the neurobiological evidence gave an average sentence of 12.83 years.
A prominent real-life instance of a person receiving a lighter sentence due to genetic disposition was the controversial 2009 case of Italy vs. Bayout, when the judge decided to reduce a murderer’s sentence to 8 years (Forzano et al. 2010). Bayout, who was diagnosed with schizophrenia, had decided to stop taking his psychotropic medication, causing him to have psychotic episodes. Due to his mental illness, he was originally given 9 years, a much lighter sentence than typical. However, during an appeal, genetic testing was performed to look for variants in the MAOA, COMT, SCL6A4, and DRD4 genes, revealing under-expression of MAOA (Fox 2009). The judge determined that these gene variants, specifically those that code for MAOA, made the man more prone to being aggressive in stressful situations, and therefore lowered his sentence again to just 8 years. This evidence was presented in combination with abnormal brain scans and reports from psychiatrists.
Both cases give strong evidence that judges in courts of law are beginning to consider biological, specifically genetic and neurological, evidence in criminal sentencing. Although controversial, this shift is a key step towards ensuring more informed decisions are being made. By doing so, judges can consider extenuating factors, such as a person’s genetic makeup or rearing environment, that may have contributed to their criminal behavior, allowing them to make a more educated decision about something that can influence a person for the rest of their life.
A pivotal distinction to make is that aggressive behavior is not always inherently bad or should be automatically linked to criminality. It can be argued that an innate drive towards aggressiveness is a natural evolutionary adaptation that allows species to survive, and potentially thrive, depending on the environment. Many species, especially social mammals, have dominance hierarchies, or societal structures in which resources are distributed based on rank (Lorenz 1966). In these situations, the mere threat of aggression, rather than the actual act of it, allows animals to conserve their energy, establish territories peacefully, and resolve conflict without direct violence.
Species also depend on aggression during mate selection. Aggressive behaviors, such as marking territory and being defensive, are employed by dominant individuals to outcompete rivals for resources such as food, water, and shelter (Lorenz 1966). Being aggressive and having accessibility to resources allows individuals the best chances for development and attracting a potential mate, in turn allowing them to pass on desirable traits to their offspring. This then strengthens the species by promoting the survival of the fittest individuals.
Conclusion
Overall, the question of why aggressive behavior occurs is not as simple as nature versus nurture; it is the interplay of nature as well as nurture that must be explored. It is clear from both animal and human models that genetics play a role in aggressive behavior. At the same time, an individual’s environment is also significant. Thus, when implicating a person in a crime, it is essential to examine both factors equally. It is also crucial to recognize that certain environments may require individuals to act more aggressively to survive; therefore, the question is raised as to whether these individuals should be treated differently than others if they are to commit a crime related to aggression.
The data presented could also be beneficial to improving the reform system. For example, it has been seen that being raised in a positive environment helps prevent these aggressive predispositions from appearing. Therefore, instead of punishing criminals by locking them in cells, putting them in a more positive environment where they could learn about the mistakes and the misjudgments in their actions may help prevent re-offenses.
It is also important not to be drawn into the misconception of causality. A person is not defined by their genes and as mentioned, can behave differently than their genetic predisposition would suggest. It is essential not to immediately stereotype people based on genetic makeup, especially in legal situations.
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