Monoamine Oxidase-A: The Gene That Controls Violent Behaviour?

There has been much talk over the years about a gene called Monamine Oxidase-A (MAO-O for short). This gene helps to limit the activity of neurotransmitters (brain chemicals) such as dopamine, adrenaline and serotonin. It has been found that people with low levels of MAO-A are more suceptable to the effects of these neurotransmitters and are thus more prone to aggressive and depressive behaviour. The following well-written article from a blog called “The Unsilenced Science” includes the following useful discussion:

I couldn't find an image of the gene MAO-A, so here's a picture of an aggressive fist
I couldn’t find an image of the gene MAO-A, so here’s a picture of an aggressive fist

This gene produces an enzyme that breaks down the neurotransmitters that activate many of the brain’s circuits. Back in the 1990’s, scientists discovered a mutation of MAOA that completely turns it off. The result is called Brunner syndrome, which only 14 related men have been known to have (plus animal models). What makes this extremely rare mutation so important is that it proves that MAOA really is a violent delinquency gene. A man with Brunner syndrome is what expert psychiatrists refer to as “a bad guy.” Five of these men were arsonists. Some of the men were rapists or attempted killers. Inexplicably, four men with the mutation somehow escaped having the syndrome, but for men with the mutation, those are not good odds. Nevertheless, out of the approximately three-and-a-half-billion men in the world, 14 really are not that many. Trust me, your neighbor—the one with the motorcycle—is probably not one of them. In conclusion, out of sight, out of mind.

The MAOA gene has a portion with repeated segments of DNA. This section of the gene is called a promoter because having more repeats increases the amount of enzyme that the gene produces (with a rare, debatable exception). After a 2002 study found that having three repeats together with having suffered child abuse is somewhat associated with violent tendencies, a flood of follow-up research ensued, and MAOA was relabeled “the warrior gene.” This version of the gene and one with four repeats are the most common versions, or alleles. These studies always had a few people with neither the 3-repeat nor the 4-repeat allele. A small number only had 2-repeats. The scientists decided that having 2-repeats in the promoter is sort of like having 3-repeats, so they invented the term “MAOA-L.” (“L” stands for low. Pretty clever, huh?) However, a pair of studies in 2008 found that the 2-repeat allele is associated with twice the rate of violence without child abuse coming into the equation. This allele is less powerful than Brunner syndrome but far more common.

Two small studies gave hints that the especially dangerous 2-repeat allele might be more common among African Americans. One study wrote that 6% of their non-white (but probably mostly African-American) male subjects had this allele. The other had 5 of 37 (14%) African-American men possessing “rare MAOA alleles.” Those percentages are remarkable given that studies of white men have suggested that 1% or fewer have this gene. 


#BlackLivesMatter’s ambivalence toward straight Black Men

#BlackLivesMatter is a movement that continues to make the headlines, years after it first emerged following the killing of Trayvon Martin by the George Zimmerman in 2012. Looking closely at the official #BlackLivesMatter website, you find that its founders have a very distinct set of ideas regarding gender and sexuality which seek to push heterosexual, ‘cis’ gendered males to the sidelines. Far from being concerned with all black lives, the #BlackLivesMatter originators appear to be mainly concerned with those Black lives which they feel have been marginalised by Black straight men.

The official Black Lives Matter crew has an ambivalent attitude toward straight black men
The official Black Lives Matter crew has an ambivalent attitude toward straight black men

The ‘About’ section of the official website of #BlackLivesMatter says the following:

“It goes beyond the narrow nationalism that can be prevalent within Black communities, which merely call on Black people to love Black, live Black and buy Black, keeping straight cis Black men in the front of the movement while our sisters, queer and trans and disabled folk take up roles in the background or not at all.
Black Lives Matter affirms the lives of Black queer and trans folks, disabled folks, black-undocumented folks, folks with records, women and all Black lives along the gender spectrum. It centers those that have been marginalized within Black liberation movements. It is a tactic to (re)build the Black liberation movement.” 

The ironic thing is that the issues which have brought #BlackLivesMatter movement to public attention are issues which overwhelmingly impact Black males. Straight Black males at that. For example, when it comes to extra-judicial killings by the police in the US, men (and especially Black men) are by far the biggest victims.

On their website, BLM also draws attention to the issue of people being locked up in prisons. They have the following two claims:

2.8 million Black people are locked in cages in this country is state violence.”

1 million Black people are locked in cages in this country–one half of all people in prisons or jails–is an act of state violence.”

The inconsistency in the figures is a common facet of campaign advocacy of this kind. Putting that aside, the naked fact is that black men are much much more likely to be imprisoned than black women. In fact, white men are more likely to end up in jail than black women! The #BlackLivesMatter website actually hides the clear gender dynamic here because they are ideologically committed to pushing male heterosexuals to the sidelines.

The overwhelming majority of black prisoners are male.
The overwhelming majority of black prisoners are male.

Now it seems that the #BlackLivesMatter movement has transcended the vision of its original founders, a fact which they rail against on their website. With this in mind, it is only right to point out that perhaps the majority of activists who mobilise under the #BlackLivesMatter banner (and who share memes on social media using the hashtag) probably understand it to be about Black lives generally. But if the movement were to stay true to the ideology of its founders, it should probably be called BlackFemaleQueerTransLivesMatter. Obviously that would never have caught on!


Why Criminals are Less Intelligent (Satoshi Kanazawa)

In a 2010 article for Psychology Today, Satoshi Kanazawa gives a suggestion as to why low IQs and criminality seem to go hand in hand:

“Criminologists have long known that criminals on average have lower intelligence than the general population, but they do not know why.  The Hypothesis may be able to shed new light on this question.

Controversial evolutionary biologist Satoshi Kanazwa
Controversial evolutionary biologist Satoshi Kanazwa

From the perspective of the Hypothesis, there are two important points to note.  First, much of what we call interpersonal crime today, such as murder, assault, robbery, and theft, were probably routine means of intrasexual male competition in the ancestral environment.  This is how men likely competed for resources and mating opportunities for much of human evolutionary history.  They beat up and killed each other, and they stole from each other if they could get away with it.

We may infer this from the fact that behavior that would be classified as criminal if engaged in by humans, like murder, rape, assault, and theft, are quite common among other species.  The criminologist Lee Ellis documented many instances of these “criminal behavior” among different species with photographs in 1998.  The primatologist Frans de Waal and his colleagues have documented brutal murders, assaults, and other interpersonal violence among chimpanzees, bonobos, and capuchin monkeys.

Second, the technologies and institutions that control, detect, and punish criminal behavior in society today – CCTV cameras, DNA fingerprinting, the police, the courts, the prisons – are all evolutionarily novel.  There was very little formal third-party enforcement of norms in the ancestral environment, only second-party enforcement (retaliation from vigilance by victims and their kin and allies) or informal third-party enforcement (ostracism).

It therefore makes sense from the perspective of the Hypothesis that men with low intelligence may be more likely to resort to evolutionarily familiar means of competition for resources (theft rather than full-time employment) and mating opportunities (rape rather than computer dating), and not to comprehend fully the consequences of criminal behavior imposed by evolutionarily novel entities of law enforcement.

Men with lower intelligence are less likely truly to comprehend evolutionarily novel entities.  Some of these evolutionarily novel entities are alternative means to resource acquisition and accumulation they could pursue instead of evolutionarily familiar means which are now classified as criminal in civilized societies.  Other evolutionarily novel entities they are less likely truly to comprehend are means that law enforcement agencies employ to detect and capture criminals.  The Hypothesis therefore offers one possible explanation for the negative association between intelligence and criminality.

At the same time, the Hypothesis also offers a novel hypothesis with regard to intelligence and criminality.  As I mention above, while formal third-party enforcement of norms is evolutionarily novel, second-party enforcement and informal third-party enforcement are evolutionarily familiar.  Thus the Hypothesis would predict that the difference in intelligence between criminals and noncriminals will disappear in situations where formal third-party enforcement of norms is weak or absent, and criminal behavior is controlled largely via second-party enforcement, such as situations of prolonged anarchy and statelessness, in fact, any situation that resembles the ancestral environment.  Paradoxically, the Hypothesis would predict that less intelligent men will commit fewer crimes if the police disappeared, although more intelligent men may commit more crimes then.”