The Biology of Violence: Ethico-Philosophical Response

Image Source: Swiss National Science Foundation

The dominant model to understand violence for the most part of the twentieth century was exclusively based on sociological and psychological models. Bruce Lipton’s, The Biology of Belief, 1 teaches that our belief has a significant role in our genetic expression and also seems to support these models to some extent. But today we have new developments in science that add information that calls us to understand violence in a new light. These new findings chiefly arise from two important branches of science today. Molecular and behavior genetics are demonstrating that most of our behavior has in part basis in genetics. Along with these developments, we can also find that some revolutionary techniques of brain imaging are opening a new window into the biological basis of crime. This study aims to understand the findings of these principles and techniques to understand our antisocial /violent behavior. These new developments raise several ethical questions and legitimate social fears. They seem to force us to leap into an eugenic society and hence, challenges us to strive to evolve appropriate ethical responses to these bold findings.


Socio-Biology of Violence

Ceasre Lombroso
Image Source: Cosmos Magazine

The scientific study of the biology of violence is said to have started in the work of Ceasre Lombroso in 1871. 2 He was an Italian army medical officer working as a psychiatrist and prison doctor at an asylum for the criminally insane in the town of Pesaro. While doing a routine autopsy he noticed an unusual indentation at the base of the  skull that he interpreted as reflecting a small cerebellum. He then proposed a theory based on these observations that the basis of the criminal behaviour was in the brain and the criminals were an evolutionary throwback to more primitive species. He suggested that criminals could be identified on the basis of a large jaw, sloping forehead, and singular palmar crease. He in fact created an evolutionary hierarchy that portrayed his eugenic orientation which placed the Jews and northern Italian on top and southern Italian, Bolivians and Peruvians at the bottom. He seems to be tilting to a theory that claimed that criminals are born. 3But in the twentieth century Lumbrosian thinking fell into disrepute and was replaced by the socio-psychological perspective of human behaviour. Thanks to new scientific fields like socio-biology, we can trace a new and refined presentation of the biological basis of violence and crime. Besides, developments in genetics and neuroscience have revealed the anatomy of violence and it has become possible to hold that there is, in part, a biological basis of violence and crime. Like violence, altruistic behaviour that leads us to cooperate with each other is learnt through the evolutionary process because of its benefits.

Genetic Basis of Violence

In the evolutionary terms human capacity for antisocial and violent behaviour was not a random occurrence. It is said that this capacity is present among the early hominids  who exhibit an ability to reason, communicate and cooperate. At this evolutionary phase, violence may have been employed as a strategy  to take away  resources from others. The females were also attracted to the brave and resourceful males. Though in our days, we perceive violence as maladaptive and aberrant, social biologists seem to suggest that violence may have been our vital survival strategy. Besides being offensive aggression to gain hold over the resources of others and to attract females, violence was also a defensive mechanism to ward off others who were competitors for their resources and females. Today we are socialized against these violent instincts and we seem to have been domesticated by the civilizing process. Along with the sociologists, the radical genetic basis of our life and behaviour is taught by geneticist Richard Dawkins in his 1976 book, the Selfish Gene. 4His thesis was that genes are ruthlessly selfish in their struggle for survival giving rise to selfish human behaviour. He makes genes the basic unit of selfishness and presents a gene-eye-view of violence and crime.

Neuroscientific Basis of Violence

PET (Positron Emission Tomography) allows us to measure the metabolic activity of different regions of the brain simultaneously. It is found that the prefrontal cortex (that part of the brain which is above our eyes and below the forehead) is the chief site in the brain to understand violence. A study of a sample of 41 persons revealed that the prefrontal cortex of some persons who were involved in murders showed a striking lack of activation. They did not exhibit any such problems with the occipital cortex which houses our vision system as it manifested strong activation (glucose metabolism). It seems to indicate that a poor functioning of the prefrontal cortex would dispose someone to violence. Although these brain imaging techniques do not necessarily establish causality, we are led to move towards it in this context. This is so because reduced prefrontal functioning can result in loss of control of the functioning of some evolutionary primitive parts of the brain such as the limbic system that generate raw emotions such as rage and anger. A more sophisticated prefrontal system keeps a control on these limbic emotions. If the prefrontal cortex is dysfunctional, these emotions will boil over. 5 Besides, research on neurological patients who had damaged prefrontal cortex exhibited tendencies to take risks, irresponsible behaviour and rule breaking. This means such people are already tilting to violent behaviour. At the personality level, any damage at the  orbitofrontal cortex triggers impulsivity, loss of self control, inability and inhibits behaviour appropriately.6


Biology of Violence and Nature / Nurture Tangle

The Violence as Public Health Problem

Deep down in the brain, below the civilized upper crust of the prefrontal cortex we have the limbic system that is the site of our emotion and more primitive parts of our neural makeup. It is here that the amygdala that fires up our emotions that trigger both predatory and affective attacks. The hippocampus regulates aggression and when stimulated sets in motion predatory attack. Thalamus is a relay station between emotional limbic systems. Mid brain when triggered gives expression to full blooded affective emotional aggression. Studies on murderers both reactive and proactive ones exhibit a higher activation of the subcortical limbic regions. Thus, behind the apparent innocent face of the criminal there is a lot bubbling under the deeper sub cortical cauldron of the brain functioning. Some researchers have also tried to demonstrate that a poorly functioning hippocampus and a dysfunctional posterior cingulate that lies more towards the rear of the head and deep inside the middle of the brain are predisposing some people to violent  anti-social and criminal behaviours. 7These studies seem to indicate that violence and crime is a public health problem and as such can be treated. Hence, we need to think of violence in medical terms.

Biosocial Factors of Violence

Violence is not only grounded in biology. The biological disposition for violence coupled with social dysfunctional upbringing has shown that the rate of crime increases four times more than those who had normal social upbringing but has biological disposition. 8 Further, it has been found that biosocial interaction leads to the onset of violence early in age. 9 But these studies somehow did not explain violence that started later in life. The social factor that aggravates the already biological disposition for violence was found to be maternal rejection like attempts to abort the foetus in Copenhagen studies  or those that were exposed to famine, starving and malnutrition  as found by the studies of New York State Psychiatric Institute were more prone to exhibit violent criminal behaviour. 10 Here one also can trace that a mother who had an unwanted pregnancy but did not take any action that suggests rejection did not seem to affect the violent behavioural outcomes of the child. It was found that maternal rejection seems to be more responsible for the launching of particularly violent carriers. 11 All this shows that the hand that rocks the cradle is ruling the world as the early period when connected with the mother really counts12 and any damage to this child mother bond can produce a psychopath adult. 13 This means some of us are born with markers of violence but social factors can aggravate our violent behaviour.

Food and Violence

The link between nutrition and violence has been studied by several researchers. Some have broadened it to include larger factors like social deprivation but found that the malnutrition leads to increased aggressive behaviour. 14 Within the malnutrition deficiency of iron was found to be more prone to facilitate aggressive behaviour. 15 It is found that children below the age of three afflicted by malnutrition also exhibit low IQ  at that age and also at the age of 11 years. 16 The decreasing scores of IQ increase aggressive behaviour. Some studies have shown that people with high fish diets do not exhibit hostile and aggressive behaviour. People with low levels of Omega-3 have been shown to be more aggressive. 17 Omega-3 has two important components: DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid). These are known to play vital roles in neural structure and function. 18 Like iron, zinc deficiency has been shown to be igniting possibilities of increased violent behaviour. Micronutrients like iron and zinc are necessary for the production of neurotransmitters and are important for brain and cognitive development. 19 Similarly it is said that a high tryptophan diet reduced aggressive behaviour. Some studies have revealed that low blood sugars lead people to both physical and verbal violence. 20 More studies reveal that lead is lethal to our brain. It is found to be  neurotoxic. The toxic effects of lead are documented by several brain-imaging studies among workers exposed to lead. It has been shown that these workers manifest a considerable amount of brain volume reduction.  It has been demonstrated that people who are in an atmosphere of lead exposure are at risk to violent behaviour. 21 Hair samples of violent offenders in the U.S have shown high levels of cadmium and has also  been linked to aggressive behaviour among children living close to cadmium mines. 22 Some say that excessive manganese can result in lowering brain functioning and lower IQs. 23 Mercury is toxic to the brain and other bodily organs but despite its toxicity, it has been shown that it does not necessarily predispose humans to violent behaviour. This has been shown by some studies on individuals with high levels of mercury in their blood but there are also other studies that have shown conflicting results regarding the propensity of mercury to induce aggressive behaviour. 24 It has been studied that it is selenium that latches onto mercury molecules and keeps it from binding with brain tissue in some cases preventing brain damage 25.


Deepening the Nature / Nurture Puzzle 

The Biosocial Enlargement

It has been well accepted that social factors do influence criminal behaviour. Now with the studies on the biology of violence, we have to talk about biosocial factors of criminal behaviour. Social upbringing, peers and neib There is body politics erupting from the bodies as they are radicalised, marked by caste/race, medically named as disabled/ diseased/ fit, theologically disembodied, consumerism by the market, digitalised by communication technology etc. ourhoods, poverty, dysfunctional brain can increase violent behaviour among humans. Biological dispositions get a social push and we find mindless human violence. Scientists have shown the link between the genes, brains and violence. But social factors cannot be kept out for these biological inclinations that  convert into full blooded psychopathology that triggers antisocial and violent behaviours among humans. Besides, changes in gene expression (Epigenetics) have been studied and environmental factors along with psycho-social factors also have been shown to play a role in the proteomics that will also affect the genomics.26 (264-265).  Such factors have  led to the consideration of biological factors in criminal behaviour leading to the emergence of neural-law in the USA27.

The Question of Agency 

The reduction of violent behaviour to biosocial factors takes away human agency. Such a view does question the existence of human freedom and seems to indicate that we are all determined by our biology and sociology and we cannot do anything about it. This simply means that the freedom that we think we have is a delusion. Therefore, our legal and justice system that is dealing with crime and its punishment is fundamentally flawed and we are punishing innocent and helpless people. This also reduces into a disease that may be cured by effecting biological changes in our brain. Primatologists like Travis Rayne Pickering teach that primates like Chimpanzees also rape murder and wage rudimentary wars28. Hence, we have the challenge to respond to new biological determinism. This means we are faced with a biology of unfreedom that seems to take away all moral responsibility in the context of human criminality.

Dangers of Neo-eugenics 

These new findings seem to have resurrected the age old racists divide. The biology of violence seems to draw a line between those who enjoy good birth and those who are born with biological predispositions for violence.  We seem to be re-inaugurating the dangerous brave new world of Aldous Huxley driving the ‘us and them’ divisions even more strongly than before.  These prospects produce legitimate fears and raise ethical questions that we have faced in the context of this rising neo-eugenics.


Facing the Biology of Violence 

Crime and Biological Cure 

With the arrival of the biology of violence, there is optimism among some regarding the possibilities of treating violence as a disease. Attending to the biological factors that induce violence has shown that conduct disorder and violence can be controlled to a large extent. While we attend to the biological pathways to violence, we have to heal the socio-psycho pathways to violence too. Besides, some reformists have used extreme interventions like castrations to reduce violent behaviours among some unmanageable people, paradoxically healing violence with violence. This makes us think how what we call biological intervention is not free from violence. Yet these studies are important to prevent individual as well as human collective violence and even total human extermination.

Neuro-Scientific Evidence and Law 

The new findings of the biology of violence have literally put the human brain on trial.  The neuro-scientific evidence seems to be interrogating our well established tradition of justice and brings mercy to the fore. As the findings of genetics and neurobiology gain wider circulation and social acceptance, the current legal system has begun to look cruel and the need for its review has begun to look more urgent.  This attention to the biological evidence to human violence is welcome and can be emancipative.

Biology of (Un) Freedom 

Biology of violence has given a hard blow to human freedom. It seems that it has put hard determinism on solid scientific footing. While we face these findings of what may be also called the science of (un)freedom, we cannot blindly accept this physicalist and positivist reductionism of human behaviour as merely brain driven.  Besides, the brain, humans also have a mind and are spiritual beings. While we embrace these important findings, we cannot fall into the reductive  traps that merely impoverish and dehumanize humans.  Hence, we may tilt to compatibilism (existence of freewill and determinism together), if not libertarianism as regards the existence of human freedom. This way we can still consider the moral responsibility of the human person for both good and evil behaviour. This means we have to critically accept the findings of the biology of violence.


The biology of violence seems to be constructing a portrait of Homo Pugnax, the violent species. The basis of violence in our biology factors without taking away the social factors is enlightening and insightful yet it has a great challenge to the existence of Human agency and consequently to moral culpability  to violent and aggressive crimes. While these findings push us towards a denial of human freedom and as such the biology of violence becomes a form of biology of (un)freedom, we resist this temptation of philosophical suicide and wish to overcome the reductive anthropology of science that does not recognize the mind and the soul. This reductive anthropology fixes human behaviour into the genes and brain mechanisms but we try to open these findings to the synergy that mind and soul have in human life.


  1. Bruce H. Lipton, the Biology of Belief: Unleashing the Power of Consciousness Matter and Miracle (Santa Rosa: Elite Books, 2005)
  2. D.G. Horn, The Criminal Body and Lombroso and the Anatomy of Defiance (New York: Routledge, 2002)
  3. Adrain Raine, The Anatomy of Violence: the Biological Roots of Crime (London: Penguin Books,2013) 11-13
  4. Richard Dawkins, the Selfish Gene (New York: Oxford University Press, 1976).
  5. A. Damasio, Decartes’ Error: Emotion, Reason and Human Brian (New York: G. P. Putmam’s son, 1994)
  6. Adrain Raine, The Anatomy of Violence, 67-69.
  7. Ibid., 76-83.
  8. Ibid., 186.
  9. Ibid.
  10. Ibid., 207.
  11. Ibid., 187.
  12. Ibid., 191.
  13. Ibid., 192.
  14. Ibid., 209.
  15. Ibid., 210.
  16. Ibid., 211.
  17. Ibid., 215.
  18. Ibid.
  19. Ibid., 218.
  20. Ibid., 222.
  21. Ibid., 223-225.
  22. Ibid., 227-228.
  23. Ibid., 229-230.
  24. Ibid., 230-231.
  25. Ibid., 231.
  26. Ibid., 264-265.
  27. S.A, Barnett, Biology and Human Freedom : an Essay on the implication of Human Ethology (Cambridge: Cambridge University Press, 1988), 41.
  28. Article accessed on 17th Nov. 2017.


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