Thread by @crimkadid

The title of tonight tweetstorm is “How are the Blacks like the Irish?”, but it’s really about how selection against schizophrenia has been a powerful influence on differences in personality and intelligence between human groups. @Steve_Sailer ,@DavidePiffer , @hbdchick

This figure shows the calculated polygenic risk score for schizophrenia among different populations. CEU (Mormons) and TSI (Tuscans) are lowest, YRI (Yoruba) and LWK (Luhya) the highest.

The author of the study believes the differences shown make polygenic risk assessment a bit absurd, as "The distributions of scores for African and European subjects hardly overlapped." biorxiv.org/content/biorxi…

I don’t believe it’s absurd. I think that what you’re ultimately seeing in that figure is a measurement is each population's disposition toward a dopamine mediated sensation seeking, a rough measure of extraversion and "interestingness".

Blacks are relaxed, fun, creative. All these traits contribute to their tendency to hit on anything nearby that looks even remotely like a woman. In evolutionary terms this is obviously adaptive; it requires no special explanation. What does is why everybody isn't like this

The answer is that such extreme sensation seeking is mediated by dopamine (Parkinson's patients taking big doses of l-dopa often become compulsive gamblers and sex addicts) and excessive dopaminergic transmission so easily degenerates into schizophrenia.

There are three dominant factors that determine schizophrenia prevalence around the world: latitude, fish consumption, and rural vs urban living. Blacks are "black" behaviorally because in their natural environment no one else had a stronger dose of all three protective factors.

This huge table is from a 1987 meta-analysis and it shows studied populations with the lowest ever record incidences of schiz. The Amish rank as the world’s least crazy people, but I have seen other papers which show an even lower rate in fish eating Polynesians.

And here is the Hall of Shame. The highest schiz rate ever recorded was from a community of settled Eskimo south of Hudson Bay. The highest European mark came from a community of Finns in far northern Sweden.

Latitude (not temperature) is the most powerful predictor of schiz because of its association with sunlight and vitamin D. New York is much colder than London, but it’s London that’s experiencing a schizophrenia catastrophe among its black population.

In the US schiz is about twice as common in urban as rural areas, but the Amish show that “rural” encompasses a lot. The strongest environmental protectants against schiz are exposure to farm animals and dogs during pregnancy. Cats increase risk:

I think all the risk factors also here apply to homosexuality, as I’ll talk about more about later: farm boys aren’t just pretending; they really are less gay than the rest of you. This set of risk factors also goes some way toward explaining very high homo rates in Jews.

Minorities have a higher risk of developing schizophrenia everywhere and a smaller minority they are in their city the greater their risk. Ethnic and cultural homogeneity reduces feeling of paranoia and distrust: the Amish do not see conspiracies everywhere.

The last important variable is fish consumption, mediated by the extraordinarily powerful anti-psychotic effects of EPA-DHA. There is no reason everyone on earth should not take fish oil, particularly high risk groups like West Africans in Britain.

Iceland is almost in the Arctic Circle and yet their schizophrenia prevalence is actually lower than the European average because they eat even more fish than the Japanese.

Finns have consistently the highest schizophrenia rates of any European people because they live so far north and yet, unlike the Scandinavians, they stupidly don't eat fish.

West Africans in their natural environment were heaven blessed to have all three protectants in the maximum dose: they live directly on the equator, malaria made urbanization impossible, and they eat gobs of fish. This map shows serum omega-3 levels around the world:

That’s the origin story of how they came to be this way but I’m going to transition now into to explaining how dopamine explains a cluster of physical and behavioral traits in blacks: explosive movement, thick and dry skin, and thick hair/eyebrows.

A quick word on dopamine: the positive symptoms of schizophrenia are treated by dopamine lowering anti-psychotics. Dopamine is often misunderstood as a pleasure neurotransmitter but it really mediates movement, specifically the will to move.

I read a paper by a doctor who prescribed anti-psychotics all the time and decided to try one himself at his university. He immediately lost the will to keep working, drove home and collapsed into an armchair for hours.

In the old days before L-DOPA, Parkinson’s patients were reduced to hobbled human statues, sitting alone all day doing nothing. There are however anecdotal reports of them all of a sudden springing into action to escape fires then immediately becoming immobile once out of danger

I have taken and am taking L-DOPA (I wouldn’t be writing these furious tweetstorms without it). The first weird thing that happened to me when I started was that I began to spontaneous tap my fingers, at first for no reason but then whenever I heard music.

I honestly didn’t know this, but finger tapping tests are the primary way to measure L-DOPA effectiveness in Parkinsonian’s patients. In addition to the tapping, my reflexes became faster and running all of a sudden became fun because I seemed to bounce off the pavement.

A lot of armchair racial theorists think that athletic differences between blacks and whites are due to T, but the literature there shows there either very little or no gap at all between races.

Blacks have longer arms and legs and lower body fat, which their climate allows. But the primary athletic advantage they enjoy is dopamine mediated burst speed.

Take a super athletic white guy, load him with unhealthy amounts of T and he will still never be able to move like this:
Even black women and children have a natural "bounce" that full grown white men lack.

Someday I’ll devote a tweetstorm to the totally unique Larry Bird, who shared Jordan’s megalomania, penchant for compulsive betting, and violently fast hands and feet. Bird was a paranoiac who spent his whole life fighting:

Blacks have an athletic advantage in almost in almost every big money sport, but the sports that most reward violent, schizophrenic bursts of speed are boxing and basketball.

The next thing I noticed in my Dopaquest was that about a week in my hair had become as thick as it was when was a teenager and then it kept getting even thicker. My eyebrows also became thick and conspicuously dark.

Again I really didn’t know this, but L-DOPA and dopamine powerfully enhance growth hormone secretion. It also stimulates ACTH, which darkens skin and hair. nejm.org/doi/full/10.10…

Blacks have higher pulses of growth hormone than whites do and much of what makes their appearance distinctive is similar to changes seen in acromegaly: thick hair and dry skin, loud, deep voices, large hands.

This is an old, well established connection between schizophrenia risk and creativity :nature.com/articles/nn.40…

In all of 1835 Europe I would be surprised if there were 1,000 part black individuals integrated into society, but from this miniscule group emerged the 1/4th black Alexandre Dumas and the 1/8th Alexander Pushkin.

In whites who are psychotic, creative, or creatively psychotic there is a noticeably increased tendency to have extremely thick dark hair and thick eyebrows. I’ll now put on a slideshow of great creative crazies of this type:

Jim Jones hair was so thick and dark that as a child his mother called him "my little Indian"

This is Syd Barrett, one of a huge number of actually schizophrenic musicians to have the "George Harrison look"

Another being Peter Green

America's most creatively accomplished/mentally ill president also had ludicrously thick, jet black hair and eyebrows.

No comment needed:

Outside of Africa, the place where this physical type is seen at the greatest frequency is among sun baked Indians, who in their natural environments enjoy very low schizophrenia rates.

The distinctive Indian pattern of extremely fast, extremely quarrelsome speech likely results from a combination of African like dopaminergic tone while possessing a normal or even superior group IQ.

Among Europeans specifically there are several populations that display unusually thick hair, thick eye brows, reputations for fast anger and an aptitude for music, dancing, and boxing. You particularly see this type in the fish eating Spanish, south Italians and Cretans.

But the group that stands apart from their close neighbors in all these ways the most starkly are the Irish. However, they’re very different from the all populations mentioned so far: way up north, little sunlight, not much fish consumption now or in the past.

The primary clue to uncovering what’s happened is that the Irish represent a European extreme in two other ways: unexposed skin that is lighter than any European people, even Scandinavians, and a continent high frequency of hemochromatosis (iron overload).

Both of these distinctive features act to preserve bone health under conditions of very high rainfall and little sunlight. Those with light skin are able to produce more Vitamin D after exposure to sunlight than the competition: researchgate.net/profile/Etienn…

The European locale that most closely resembles Ireland on maps of rainfall and sunlight is Iceland, which more extreme in both dimensions. Icelanders have also been found to possess abnormally high iron stores: sciencedirect.com/science/articl…

I think Ireland and Iceland, both rain soaked and sunless, may be the only two places on earth where alcoholism was selected for because consumption linearly increases ferritin stores in blood. An old farmer may have found it easier to get a hold of booze than animal protein.

Icelanders don’t have problem drinking rates higher than other Europeans, but this is confounded by the fact that they enforced prohibition until NINETEEN EIGHTY-NINE. I don’t think they were just being sticklers: there is something funny going on here.

But circling back to the main point: In Coon’s The Races of Europe I believe the Irish are the only group singled out for the thickness of their bones and part of the mechanism has probably been a ruthless selection for both light skin and high baseline levels of Vitamin D.

D helps protect Irishmen against rickets and inflammatory diseases, but an expected benefit of the selection was this it provided them with a stronger immunity to schizophrenia than any other North European people. Psychotism is a plus if your body can handle it and they could.

An indicator of how ruthless selection was for skin color specifically can be seen in the contrast between extremely light Irish skin, moderately light eyes, and their surprisingly dark hair. Black Irish hair color may also have a different cause, mediated by dopamine>ACTH.

One manifestation of excessively high glucocorticoids like ACTH is Cushing’s Syndrome, whose symptoms are described by Wikipedia in the following way:

So are there populations that have gone the other way: where selection against schiz has taken place? You would expect it to happen in urbanized places of the far north and there is some evidence in the clump of low hanging dots in the CEU sample here.

About ¼ of Mormons have Scandinavian surnames, principally Danish and Norwegian, and I think the low hanging cluster of dots on the bottom of CEU represents individuals of majority Scandinavian descent that I know to exist in the dataset.

Scandinavians are under strong selective pressure to keep schizophrenia low, but their high consumption of fish both reduces the power of that pressure and redirects it away from acting directly upon schiz causing alleles and instead improving omega-3 metabolism instead.

The population that has probably been under the most ruthless selection again schiz per se are the Finns, who along with their Estonian cousins have the highest PISA scores in Europe. Pfiffer also calculated them as having highest the Edu Attainment PGS of any Europeans.

Schizophrenia risk increases with every IQ dropped and the same genes that increase schiz risk also impair mental function in normals: nature.com/articles/s4138…

Selection against nuttiness may also help to explain the distinctive Nordic personality: in other words, why they’re so boring. The positives to being sane are obvious; the downsides are that you find yourself living in a country where people stare at a burning log on Christmas.

There's a lot more to write about this, but these are the big points. In my next dealie I'm going to try to figure out what changed around 1985 that led to the current autism explosion and explain how it affected even non-autistic millenials.