The vast majority of murders are committed by men. Why?

Are men ‘hardwired’ by evolution to be killers? Or is it imprinted upon them after birth by their experiences? The statistics are being investigated by scientific debate.

Why do men kill? It’s a classic debate. And the answer depends upon whom you ask.

The statistics are brutal. Undeniable.

But they’re not specifically revealing.

Australian males are six times more likely to commit homicide than females, according to data collected by the Federal Government’s Crime Statistics Australia. And 75 per cent of all murders were of an acquaintance or domestic partner.

Why?

It’s something sociologists and evolutionary psychologists have been arguing about for decades.

They’re no closer to agreement.

It all comes down to separating the influence of nature and nurture - the role of hereditary genetics, versus that of the environment you grow up in.

Science has been attempting to figure out what drives people to kill for decades.

DISSECTING THE DATA

A recent World Health Organisation study assembled gender-based violent crime data from 63 countries. The diversity was deliberate — it was an attempt to determine cross-cultural trends.

Most previous studies had tended to focus on Western populations.

So, how much of male behaviour could be attributed to culture they were raised in?

Overall, that male teenagers were almost three times more likely to have been in a fight than females, hinting at some degree of genetic predisposition.

But, the rate of offending varies dramatically between cultures.

And not in ways that are expected.

“But when we looked at female involvement in frequent fighting, we found this varied substantially across societies, perhaps more than evolutionary perspectives would expect (ranging from 0.07% [Tajikistan] to 25% [Samoa]),” it reads.

The researchers argue the variation in these figures indicate “some forces that drive physical aggression are not sex-specific”.

Other findings were counterintuitive: the study’s analysis showed that sex differences actually decrease as gender inequality increased.

But, perhaps we shouldn’t be surprised.

The researchers suggest this may be because those societies physically separate young males and females, and impose a severe stigma upon premarital sex and relationships.

“This segregation of adolescent male and female life spheres may limit the kinds of male formidability competitions that are likely one of the motivational roots of fighting among adolescent males.”

In other words, there’s less opportunity to fight over girls.

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Born bad? Or made bad? The role of nature versus nurture in male homicide is hotly debated.

NATURE OF THE BEAST

Australia has about one murder per 100,000 people each year. This is compared to America, with five and South Africa at 34.

In all cases, males are by far the most prevalent killers.

The reflex-response is to examine a killers upbringing. Were they under-privilidged. Were they abused? Or were they simply ‘born evil’.

Research indicates a strong link between childhood abuse and murder. But, undeniably, not all horrifically abused children become killers.

So nurture in itself cannot be either entirely blamed or dismissed.

Science argues an absent or violent father can result in a ‘lack of love’, meaning young adults are deficient in compassion and empathy. And this can lead to aggressive, domineering behaviour.

Blame is also reflexively aimed at mothers: were they insufficiently upright and chaste? They certainly can play roles — such as a domineering parent striving to keep their child ‘pure’ and ‘virginal’, equating physical attraction with ‘sin’.

Again, not all male children of strict puritanical parents become killers.

And what about when a murderer — such as serial killer Ted Bundy and cannibal Jeffrey Dahmer — comes from a loving, stable home?

Is it the neighbourhood they live in? Peer pressure? Community expectations? Religion? Politics?

Some mix of the above is almost always present. But rarely is it solely at fault.

So something else must also be at play.

Serial killer Ted (Theodore) Bundy appeared to come from a healthy home. So what drove him to kill?

‘WARRIOR’ GENES?

For thousands of years, animal breeders have known personality traits are passed down through bloodlines. And they’ve used this knowledge to actively intervened in breeding to produce either docile lap-dogs or vicious fighting varieties.

But does such thinking apply to humans?

We know what works for a lab rat often does not translate to human medicine.

What about murder?

We inherit our eye colour from genes, and tendencies towards height and weight. Not to mention a wide variety of diseases — including mental conditions.

And one particular variant of a human gene, labelled MAO-A, has been dubbed the ‘warrior gene’ because it has been found to have an association with violence.

Defence lawyers have seized upon its discovery, arguing in courts that its presence makes killers ‘vulnerable’ to violent activity.

But, again, the gene alone is not enough.

Scientific studies have shown that, when combined with child abuse, the chances those with the gene becoming a violent offender skyrocket more than 400 per cent.

But is that an excuse?

“A person doesn’t choose to have this particular gene or this particular genetic makeup,” argues forensic psychiatrist William Bernet of Vanderbilt University. “A person doesn’t choose to be abused as a child. So I think that should be taken into consideration when we’re talking about criminal responsibility.”

Access to weapons is a major contributor to a decision to kill.

CHOICE AND CONSEQUENCE

The search for the source of a murderer’s motive is complicated. It’s also far from complete.

Genetic correlations are sometimes identified. And there’s often factors such as adoption, alcohol, education, social interactions and expectations.

But for every killer, there are dozens with a similar mix of circumstances that don’t kill.

This indicates people may be set down a path by their personal mix of nature and nurture. But, in the end, it’s a matter of choice.

Science indicates both nature and nurture produce killers.

Researchers are seeking a refinement of how much influence each contributes, whether one always needs the other, and how to intervene before any ‘tipping point’ is reached.

What we also know is murder can be mitigated.

The decision to kill is often a snap one. And the choice is made easier with the availability of weapons.

In Australia, murder, as a whole, has declined by almost 25 per cent over the past 25 years. This can largely be attributed to the post Port Arthur massacre restrictions on firearms. The number of murders involving guns fell 57 per cent between 1989-90 and 2013-14.

When in a fit of rage, few Australians have a firearm within arms reach.

Knives are not as destructive and are much more ‘personal’ because of the close proximity they must be used in. Poison takes time and premeditation.

All this gives perpetrators an opportunity to consider their decision — and its consequences.

@JamieSeidelNews

Originally published as The vast majority of murders are committed by men. Why?