Born to kill?

Born to kill?

Jeffrey Dahmer from Milwaukee, Wisconsin, USA was a serial killer preying on gay black men, a sex offender who occasionally indulged in necrophilia and cannibalism. The TV series “Dahmer: Monster - The Jeffrey Dahmer Story” became Netflix’s 2^nd biggest series ever a few weeks after its release.

Another notorious serial killer was Ted Bundy who kidnapped, raped and murdered young women. And like Jeff and Ted, there are many other serial killer psychopaths who have plagued society in the past.

What triggers these individuals, the vast majority of whom are male, to become serial killing monsters? Are they born with one or more genetic anomalies or mutations that pre-dispose them to exercise uncontrolled violence against other human beings?

The short answer is YES but more factors are involved than genetic mutations alone; it is a matter of nature viz. genetic pre-disposition regulated by nurture i.e. upbringing that can override the potential psychopath’s genetic pre-disposition to put his urge for violence into action.

James H. "Jim" Fallon is a brilliant American neuroscientist born to an Italian American family, a professor of psychiatry and human behaviour, whose interests include brain imaging, chemical neuroanatomy and circuitry, brain imaging, adult stem cells and more. His best selling book, The Psychopath Inside: A Neuroscientist's Personal Journey into the Dark Side of the Brain, published in October 2013 is highly recommended to anyone interested in the topic of psychopathy. The interested reader can check out Wikipedia for details on his extensive interests, knowledge, scientific contributions and academic brilliance.

Jim Fallon also has English and Irish ancestry some of whom where murderers as he reveals in his book.

After studying the brain scans of numerous psychopaths, Jim Fallon discovered reduced connections between the part of the brain responsible for sentiments such as empathy and guilt and the amygdala, which controls fear and anxiety. To quote Fallon: “ In psychopaths, I saw a loss of activity that extends from the orbital cortex into the ventromedial prefrontal cortex and into a part of the prefrontal cortex called the anterior cingulate. The loss then continues along the cingulate cortex to the back of the brain as a thin strip, then loops down into the lower part of the temporal lobe into the very tip of the temporal lobe and the amygdala.” Psychopaths have a normal dorsal system that thus allows them to plan and execute predatory behaviours without being deterred by emotions such as guilt, empathy, fear or anxiety and this also allows them to be highly manipulative.

The authors of a study Tiihonen et al. in “Neurobiological roots of psychopathy” found that “expression levels of RPL109, ZNF132, CDH5, and OPRD1 genes in neurons explained 30–92% of the severity of psychopathy, and RPL109 expression was significantly associated with degree of psychopathy also in astrocytes. It is remarkable that all the aforementioned genes except OPRD1 have been previously linked to autism and might thus contribute to the emotional callousness and lack of empathy observed in psychopathic violent offenders”. In other words, the anomolous functioning of certain parts of the brain are due to specific genetic mutations. 

Another interesting discovery is related to Monoamine oxidase A, also known as MAO-A, an enzyme that is encoded by the MAOA gene and catalyses the oxidative deamination of amines, such as dopamine, norepinephrine, and serotonin. Mutations in the MAOA gene results in monoamine oxidase deficiency (Brunner Syndrome) and are associated with other disorders including Alzheimer's disease, aggression, panic disorder, bipolar disorder, major depressive disorder, and attention deficit hyperactivity disorder. The MAOA gene has a promoter that comes in either a short form or a long form. The short promoter has been associated with aggressive behaviour and is called the “warrior gene”. Fallon discovered that psychopaths possess this aggression-related “warrior gene”. 

To summarize, psychopaths are born with mutations that cause an anomolous functioning of the brain as well as mutations that lead to the presence of a “warrior gene”.

When studying the brain scans of psychopaths, Jim Fallon used the brain scans of members of his family himself included as a reference of a normally functioning brain. To his complete astonishment, he was shocked to discover that his own brain scan showed the same patterns as those of the psychopaths that he was studying. After numerous analyses of his own behavioural patterns (neurological analyses, psychoanalysis, detailed discussions with family members and friends), he concluded that he did carry many of the traits of psychopaths e.g. lack of empathy, lack of remorse, willingness to take exaggerated risks without any fear of the consequences, manipulating others into very risky situations without their knowledge and so on but he was by no means a killer or murderer. He attributed this fact to a very stable childhood and an excellent upbringing. Based on his studies and experience, he formulated his three-legged stool explanation for the etiology of psychopathy:

1. unusually low functioning of the orbital prefrontal cortex and anterior temporal lobe, including the amygdala
2. the high-risk variants of several genes, the most famous being the warrior gene
3. early childhood emotional, physical, or sexual abuse.

Unlike himself who was brought up by loving and caring parents, practically all the psychopaths he was studying had experienced emotional, physical and/or sexual abuse. Thus, the nurture factor has a major influence on whether or not an individual carrying the mutations prevalent in psychopaths actually becomes one.

The vast majority of psychopaths are men and there is a logical explanation for that. The warrior gene, that has also been linked to changes in brain structure, is located on the X chromosome, one of the two sex determining chromosomes, the other one being a Y chromosome in males and another X chromosome in females. In order to be affected, men need to have the warrior gene in their X sex determining chromosome, whereas women would need to have it in both their X sex determining chromosomes and the probability for that to occur is consequently much smaller.

About 2 percent of individuals in all societies possess psychopathic traits even though only very few of them will turn into murderers or serial killers. As strange as this may seem, this fact indicates that these traits are beneficial to society or else evolution would have eliminated them. Psychopaths show strong leadership qualities; they have been found to make better financial decisions under risk, they face stressful situations without emotions, their narcissism enables them to succeed where others would not even dare to try. Thus, their traits give them specific advantages that can be beneficial for the survival of society. 

Sources:

James Fallon, “The Psychopath Inside”, Portfolio/Penguin, NY

Tiihonen, J., Koskuvi, M., Lähteenvuo, M. et al. Neurobiological roots of psychopathy. Mol Psychiatry 25, 3432–3441 (2020). https://doi.org/10.1038/s41380-019-0488-z)