different ethnicities have different % of "anger," "warrior" gene carriers?

[latent aaaack]

I know the most widely held belief on this topic in previous threads has been that evolution has not separated humans enough to cause observable differences at the group level in behavior and in the brain. Hence me posting these recent research studies in which (although fairly tepid by themselves) the flat opposite seems to be stated. Should research like this even be carried out if someday it may lead to the scientific racist hypothesis being even partially proven?

The first new article I came across a couple months ago and me reading it lead me to do a little more reading about older similar studies. Again, the point is not the significance of the findings themselves but rather that they seem, to me anyway, to contradict the widespread consensus that there couldn't have been enough time for evolution to cause group differences involving brain structure/function. Are there some places science shouldn't go?

http://www.telegraph.co.uk/scienceandtechnology/science/sciencenews/5270316/Anger-is-in-the-genes.html

Isolation of a gene called DARPP-32 helps explain why some people fly into a rage at the slightest provocation, while others can remain calm.
...
Those who had the "TT" or "TC" versions of the gene portrayed significantly more anger than those with the "CC" version.
...
TT and TC versions are much more common in Western populations, with the researchers suggesting that demonstrations of anger can help people get ahead in life.
http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=10395334&pnum=0


Maori "warrior gene" linked to aggression

A New Zealand researcher claims there is an over-representation of the "warrior" gene, which has been linked to aggressive behaviour, in Maori men.
Dr Rod Lea said the monoamine oxidase gene, carried by a large number of Maori, could be key to addressing health issues.
....

Dr Lea said today he believed the influence of the gene, which appeared to feature in about 60 per cent of Maori men compared with 30 per cent of European men, could be small.From a link on wiki about this gene:
http://www.springerlink.com/content/ruvatc6nkuldw0y6/
Abstract We describe a new polymorphism upstream of the gene for monoamine oxidase A (MAOA), an important enzyme in human physiology and behavior. The polymorphism, which is located 1.2 kb upstream of the MAOA coding sequences, consists of a 30-bp repeated sequence present in 3, 3.5, 4, or 5 copies. The polymorphism is in linkage disequilibrium with other MAOA and MAOB gene markers and displays significant variations in allele frequencies across ethnic groups. The polymorphism has been shown to affect the transcriptional activity of the MAOA gene promoter by gene fusion and transfection experiments involving three different cell types. Alleles with 3.5 or 4 copies of the repeat sequence are transcribed 2–10 times more efficiently than those with 3 or 5 copies of the repeat, suggesting an optimal length for the regulatory region. This promoter region polymorphism may be useful as both a functional and an anonymous genetic marker for MAOA.

http://www.sciencedaily.com/releases/2009/06/090605123237.htm
'Warrior Gene' Linked To Gang Membership, Weapon Use


ScienceDaily (June 8, 2009) — Boys who carry a particular variation of the gene Monoamine oxidase A (MAOA), sometimes called the "warrior gene," are more likely not only to join gangs but also to be among the most violent members and to use weapons, according to a new study from The Florida State University that is the first to confirm an MAOA link specifically to gangs and guns.
...
"Previous research has linked low-activity MAOA variants to a wide range of antisocial, even violent, behavior, but our study confirms that these variants can predict gang membership," he said. "Moreover, we found that variants of this gene could distinguish gang members who were markedly more likely to behave violently and use weapons from members who were less likely to do either."
The MAOA gene affects levels of neurotransmitters such as dopamine and serotonin that are related to mood and behavior, and those variants that are related to violence are hereditary. Some previous studies have found the "warrior gene" to be more prevalent in cultures that are typified by warfare and aggression.


Anyone aware of more details and sources about these claims? What is the basis for the last highlighted claim?

[Dancing David]

So, hmm, you have yet to demonstrate that there are racial differenecs in the expression of genes. Even if the base studies are true, which I kind of doubt they have sample bases of 100,000 or good sample controls.

ETA: You would need to study large control groups as well to see what the prevalence of the gene expression is in different demographic groups and then the level of expressed violence. As well a good metric on the level of expressed violence.

There is also a correlation between ADHD and criminal activity. But none of this measures differences between large population of humans.

[HansMustermann]

"the gene, which appeared to feature in about 60 per cent of Maori men compared with 30 per cent of European men"

You know, the sad thing is that someone out there will make it sound like some kind of vindication of racism, completely missing the points that:

- 30% of Europeans have it too, and

- 40% of Maori don't

[latent aaaack]

Isn't this what the studies I cited did? I can't find the original research but these are quoted research results in legit media and scientific sources that says there's a difference. I don't understand what you're referring to with the 100,000 number - I've never known a sample to need such a large number.

So, hmm, you have yet to demonstrate that there are racial differenecs in the expression of genes. Even if the base studies are true, which I kind of doubt they have sample bases of 100,000 or good sample controls.

ETA: You would need to study large control groups as well to see what the prevalence of the gene expression is in different demographic groups and then the level of expressed violence. As well a good metric on the level of expressed violence.

There is also a correlation between ADHD and criminal activity. But none of this measures differences between large population of humans.

[Dancing David]

Isn't this what the studies I cited did? I can't find the original research but these are quoted research results in legit media and scientific sources that says there's a difference. I don't understand what you're referring to with the 100,000 number - I've never known a sample to need such a large number.


The main issue is that you have to be very cautious in making conclusions based upon small samples. populations and expressions of behavior.

Um it goes like this:

I am fairly certain that the studies you have mentioned have very small samples, I would guess that they are fewer than 100 inclusive of control groups. Maybe under 250 if they were really big studies.

That is not population genetics. To study population genetics needs very large samples, the FDA large trials barely approach 10,000. They can only indicate general trends in subset populations. And they do rely heavily on semi-random sampling (I say semi-random because they only deal with those who present for treatment.)

Now in the cases you mentioned the original studies would be crucial to making any claims about larger population, these are the possible reasons.

Selection bias: they most likely chose individuals who has already expressed traits (IE multiple convictions for certain crimes) and then found this marker for the MAO trait, which is fine. However until you go and survey a large percent of the possible population, find a large random sample of carriers of the trait then you can not say what possible correlation there is between the trait and aggressive behavior. So you need a population sample to
-determine the rate of the appearance of the trait in the population
-determine the frequency of expressed violence in the presence of the trait
-determine the frequency of expressed violence in the absence of the trait.


Population sampling and subgroups: the determination of traits within populations is very tricky, often the expression and presence of a trait within a population is wider than the expression and presence between groups. As a larger population set I would assume that the Maori and other study populations are heterogeneous, with large variation between subgroups of the general population. Without data sets that identify sub groups and large random samples within the general population it would be very difficult to say anything about the presence of a trait within anything except for the very small original sample group.

Therefore any conclusions about this being a trait amongst certain populations would be speculative. Especially without a larger sample group from random samples outside the 'Maori' population, it could be that it is a trait limited to certain subsets of the 'Maori' population, it could be that it is a widely distributed trait across many population groups.

Demographic matching: the expression of traits is rather interesting as they can set thresholds on tolerance for frustration, mood and the like. Especially when you are dealing with MAO, which is a clean up enzyme in the post synaptic cleft. This enzyme will effect most neural systems and neuro-transmitters. So in the expression of a trait such as 'level of expressed violence', it may be that history, social setting, adaptive learned behaviors and socio-economic variables have a huge impact upon the expression of the trait. People with lower tolerance for frustration (as just an example) will respond differently to high stress levels dependant upon all those factors. So you would have to use large sample sets and demographic matching and variation to rule out that you are not just seeing a consequence of a demographic stress upon the individual.
So again you would want a large population of people, those who have the trait and those who don't. Then you would want to compare levels of violence against different demographic metrics. If the traits is significantly associated with violence across most demographic metrics that would be very indicative. If the absence of the traits has a significant correlation with low levels of expressed violence across all demographic metrics that would be indicative.
If there is a significant marked difference between presence and absence of the traits and significant reverse correlation with expressed violence within demographic sets then that would be very indicative.

[Dancing David]

Did a little looking at the "Monoamine oxidase A genotype is associated with gang membership and weapon use" article, it is in a journal that you have to subscribe to read, at least currently.

It would appear that they used data from a large longitudinal study on adolescents and that somewhere there was a sample of 2,500. (I don't know if the overall sample was 2,500 or if the population studied was drawn from another study of 2,500)

But importantly I can't find anything about sample, control sample, population controls and demographic controls.

So to say that different ethnicities express the trait at any level is sort of unwarranted until large sample demographics occur.