The Evolution of Violent & Aggressive Behaviours

Violence throughout history has been due to conglomerate number of reasons; some researchers argue this is due to the prehistoric nature of man, whilst others argue it is response to environmental issues such as overpopulation. Human violence can be seen to be associated with food shortages and overcrowding especially among those in poverty and lower social classes. But is man’s aggressiveness really inherent? - It can be argued that those who are more affluent in society would show less violent mannerisms. However, in more affluent areas of England and Wales the crime rates more than doubled during the 1950’s to 60’s and amongst other wealthy areas (Russell & Russell, 1979). A consequential study was conducted by Russell & Russell on monkey populations.

They made a direct comparison of monkeys living in the wild and monkeys in the zoo – they both shared an abundant supply of food. Thus, the major differences they observed were the violence and quarrelsome behaviour from the Zoo monkey’s due to the lack of space and freedom to roam. A dictatorship from larger, more powerful male in the Zoo was also noticed in this study; this feature was also seen in other population studies that were conducted previously. Following on from this it can be understood that mammals much like man do have the ability to behave in a calm, merciful manner if the surrounding conditions allow it. An observation made by Stanislav Andreski highlighted that when prisoners of war were being released they proceeded to draw around their bodies the outline of space they wanted (Russell & Russell, 1979). In an attempt to gain a scientific understanding behind primitive and human behaviours – a study was conducted recently which showed that the level of violence interpersonally predicted among humans was very similar to that of primates, highlighting that lethal violence was embedded deep in the ancestry of humans (Gomez, Verdu, Gonzalez-Megias & Mendez, 2016). Overall the prevalence of aggression is high amongst animals, so what can be expected of humans?

Fundamentally it is understood that violence is a public health problem and continues to grow globally. The Lancet Journal, 2002 stated that changes are needed in refocusing the attention to reducing violence through behavioural, social and environmental means, through policies, legislature and public health awareness i.e. media campaigns and reducing risk factors (Krug et al., 2002; Mercy et al., 1993). On the other end of the spectrum, it is necessary to understand where violence and aggressive behaviour comes from, how it is manifested in humans today and how does it shape and mould the youth. Violence is not a new phenomenon, with recent indication showing that the most brutal massacre took place around 10,000 years ago in Naratuk, Africa (Seemangal, 2016). Violence can serve important functions for a society and species, in which the dominant prevails and the weak are eliminated, aiding in the individuals remaining in the species to adapt to new surroundings and become superior, impertinent and faster.

In animals, aggression is used between dominating males to develop a hierarchy and to intimidate other males, allowing females to only mate with more ‘powerful’ of males (Benton & Brain, 1979; Miczek et al., 2001), whilst also competing for food sources and territory. Since World War II, in which around 50-80 million people were slaughtered, homicide rates have notably increased, with 12% higher than last year in the United Kingdom alone (Office for National Statistics, 2018). With children shooting classmates in schools (Fernandez, Fausset & Bigood, 2018), gun and knife crime increasing (Weaver, 2018) and drug busts (National Crime Agency, 2018) becoming the ‘new normal’ is this the decline of civilisation as we know it?

This review seeks to understand the relationship between genetic heritability of criminal tendencies in a variety of individuals whilst taking into account gene x environment interactions. A range of genes polymorphisms will be reviewed, however the most relevant being Monoamine Oxidase A (MAOA), dopamine and serotonin levels through meta critical analysis and longitudinal studies.