Thread by @SocDoneLeft

Joe Rogan recently platformed a racialist who argued that "black Americans" and "Africans" have a "proclivity to violence" because of "the MAOA gene", also known as the "warrior gene".

This is a common race realist talking point, and it is deeply misleading. Thread:

BACKGROUND:

What is "the warrior gene"? Oversimplified for Twitter:

- "The MAOA gene" has multiple variants
- MAOA variants can be lower activity or higher activity
- Lower-activity MAOA variants causes higher violence

geneticliteracyproject.org/2018/02/20/cha…

PROBLEM 1: RACE MISMATCH

The most obvious absurdity with racialist claims about MAOA and violence:

Low-activity MAOA variants are most common in Asian genetic samples -- the continental group with the lowest violent crime rates in the US:

This raises an obvious question: If continental low-activity MAOA rates don't neatly line up with crime rates, why did some scientists start believing that low-activity MAOA causes higher violence?

PROBLEM 2: WEAK AGGRESSION

Many individual studies found that low-activity MAOA correlated with much higher aggression in experiments.

However, this correlation appears much weaker in meta-studies (which combine many studies at once) and GWAS (which examine many genes at once).

For example, the Ficks and Waldman 2014 metastudy found that people (mostly male) with low-activity MAOA variants had ~1.1x higher anti-social behaviors (ASB, basically aggression and violence).

This is a significant increase, but a very modest one: sci-hub.st/10.1007/s10519…

Conversely, the Vassos et al. 2014 GWAS meta-study found that males with low-activity MAOA variants had insignificantly different aggression or violence (confidence interval .97x to 1.19x) -- in fact, no single gene had a significant effect: sci-hub.st/10.1038/mp.201…

Similarly, the Rautiainen et al 2016 GWAS on 176 people diagnosed w anti-social personality disorder found no significant MAOA correlation, despite finding other significant genes.

(MAOA variants are on the X chromosome, which had no significant results): sci-hub.st/10.1038/tp.201…

What's the TLDR of these GWAS studies?

Most genes have a small effect on violence. It's possible that low-activity MAOA variants cause higher violence -- but any effect is likely to be small, and evidence is consistent with no effect.

This is a classic problem with "candidate genes" for violence and intelligence:

A few smaller studies examining one gene find strong results, but then larger studies examining more or all genes find weak or no effects.

PROBLEM 3: GXE

Let's pretend that the evidence for low-activity MAOA is stronger than it appears and that it aligns with racialist categories.

There remains a massive problem for racialists: Gene-environment interactions (GxE or GXE).

Some of the earliest research on MAOA variants found that low-activity MAOA predicted higher antisocial behavior -- but only among adults who had been abused as a child: geneticliteracyproject.org/2018/02/20/cha…

This finding has had mixed replications.

However, overall, the Byrd & Manuck 2014 metastudy found that males w/ low-activity MAOA allele had significantly stronger effects from childhood maltreatment on violence than males with high-activity MAOA alleles: sci-hub.st/10.1016/j.biop…

Their findings suggest that low-activity MAOA increases "maltreatment-dependent risk for a range of conduct problems, and not aggression or criminal violence specifically."

Or: MAOA doesn't directly increase violence, but may increase the effect of child abuse on violence.

This is an example of a GxE effect: The low-activity MAOA variant doesn't just universally shift violence upward.

Instead, if MAOA does have an effect on violence, it's through multiplying the harms of child abuse and neglect on increasing adult violence.

This suggests an environmental solution, not a racist solution: We need to fight for lower child abuse and child neglect.

That's an achievable and worthy goal: Home nurse visits, social insurance, and preventative sex ed all reduce abuse rates:

TLDR:
- The "warrior gene" is most common among people of Asian origin, not African.
- The "warrior gene" has weak-to-zero effects on violence.
- If the "warrior gene" increases violence, it's by increasing the effect of child abuse on violence. The solution? Fight child abuse.