Richard Lynn (circa 1990) believed that if 20th century nutrition had caused average head circumference in children to increase by 1 standard deviation over several decades, then nutrition had also caused IQ to increase by 1 standard deviation over several decades. Thus, nutrition was Lynn’s primary explanation for the Flynn effect.
Then Jensen came along (circa 1998) and argued that since brain-size only correlates 0.4 with IQ (an overestimate), then a 1 standard deviation increase in head size would only cause a 0.4 standard deviation in IQ, and you needed cultural explanations to explain most of the Flynn effect.
I decided to look at an excellent study that Lynn had cited. In this study you had 14 pairs of identical twins (one born undernourished, the co-twin born well nourished as measured by birth weight; twin pairs were raised in the same homes). At an average age of 13, they had their head circumferences measured and were given the WISC IQ test.
The heavier twins had crania that were 0.64 cm bigger than their undernourished co-twin. At age 13, the within sex standard deviation for head circumference appears to be 1.31 cm, so that’s a difference of 0.49 standard deviations.
When it came to verbal IQ, the well-noursihed twins and the undernourished twins had the exact same average IQ. And when I saw the exact same average IQ, I mean the exact same average IQ: 98.29 vs 98.29 (unadjusted for old norms)
However when it came to performance IQ, the well nourished twins scored 7.07 IQ points higher than their undernourished co-twins. That’s a difference of 0.47 standard deviations, virtually identical to the 0.49 standard deviation difference in head circumferences.
So it seems that Richard Lynn was half-right. Brain size gains caused by prenatal nutrition do perfectly parallel IQ gains caused by nutrition, but only when it comes to Performance IQ. Prenatal nutrition seems to have virtually zero impact on Verbal IQ, though given the small sample size (only 14 twin pairs), these conclusions are tentative.
The implications for the Flynn effect are unclear because we don’t know how much brain size has increased over the 20th century. If if measured by head size, brain size gains appear to be huge, but if measured by brain weight, they appear more modest.
Pumpkin Person 
Pumpkin Person“So it seems that Richard Lynn was half-right. Brain size gains caused by prenatal nutrition do perfectly parallel IQ gains caused by nutrition, but only when it comes to Performance IQ. Prenatal nutrition seems to have virtually zero impact on Verbal IQ, though given the small sample size (only 14 twin pairs), these conclusions are tentative.”
This precisely matches my profile if you are correct.
This also explains why my brother is much faster than me.
He is completely uninhibited at achieving his goals.
Most of the time I don’t know what my goals should be?
Recently (because of Prozac) I have better impulse control without anxiety. Intuitively I am realizing that my body is just a conduit for energy to pass through. Music is more expansive for that reason in my headphones. It is now one fifth the volume I had it on before.
“However when it came to performance IQ, the well nourished twins scored 7.07 IQ points higher than their undernourished co-twins. That’s a difference of 0.47 standard deviations, virtually identical to the 0.49 standard deviation difference in head circumferences.”
Does the study say how much of the brain size – IQ correlation remains in the well nourished sample ?
No, but some of the largest correlations between IQ and brain size have been found in well nourished, even elite samples (Canadian university students).
Ok, can you please share your references ?
https://www.researchgate.net/publication/222881180_In_vivo_brain_size_and_intelligence_Intelligence_15_223-228
the current ‘mer’can presidential race demonstrates the un-solvable problem with ‘mer’ca.
the only candidate who does NOT have any non-american grandparents is clinton.
i was wrong!
hillary’s father’s father was an immigrant.
n/a and i can agree…that america was better in 1860 than it has been…ever since.
my mother’s father’s father was an immigrant…from liverpool…like the beatles.
i meant my mother’s mother’s father.
and he was “middle class”.
that is, he wasn’t an economic refugee.
he was a captain in the merchant marine and ship builder.
just like my surname’s family.
he came to america for reasons other than desperation.
And the Clintons cheer on the demographic replacement of Americans. American elites are not only useless but malignant, and they spread their malignancy to other places by force.
If I recall my web research correctly, some of the ones who dropped out did not have immigrant parents and/or grandparents.
Also, since Obama’s dad was only here temporarily, technically Obama Jr. does not have recent immigrant ancestry. Technically.
Im in the camp that the “Flynn Effect” (which is meaningless, really) is due to better nutrition. We know the deleterious effects of bad nutrition on cognition and brain size. For instance, lack of protein, b vitamins, iron and zinc all lead to depressed brain size as well as decreased IQ and antisocial behavior, having children act out. If your nutrition isn’t as good as it can get prenatally, you will have those negative effects. ESPECIALLY if it happens in the second trimester, as that’s when most growth happens. I touched on this head in my post about IQ, disease, nutrition and parasitic load.
http://notpoliticallycorrect.me/2016/01/15/iq-nutrition-disease-and-parasitic-load/
No idea why the Flynn Effect keeps getting brought up to be honest. Yea IQs are increasing anywhere you look, BUT those genetic differences reamain intact, PROVING that these differences are genetic in origin.
Lets say Flynn is right. The average black now is as intelligent as the average white in 1945. That’s supposed to show that the race difference in IQ is environmentally caused, because there hasn’t been that much genetic change in the white population and the IQ has allegedly gone up 15 points. So, you can have a 15 point difference created by just an environmental change, no one knows why. Some think better nutrition or malnourished brain, etc. That’s also a fallacy. Just because a change in one group over time is due to an environmental change, doesn’t mean, or even make it probable, that a difference between 2 groups at the same time is due to an environmental change. The Flynn Effect make’s that highly unlikely and here’s why.
The Flynn Effect, assuming it’s real, has been acting completely uniformly in every population. Any country you ask, the rate of increase is 3 per decade. That means it’s an environmental factor that effects whites and blacks the same way as well as the whole world. And as a result of this uniform environmental factor, you have a difference in IQ that’s being preserved. That would suggest that the response on the parts of blacks and whites is due to some non environment factors, a genetic factor, which is making the difference in IQ remain constant as the Flynn Effect goes into effect.
What makes it even more unlikely, in the last 60 years, their environments have become very similar since segregation. These differences don’t exist now, they go to the same schools by court order, same TV shows, same movies, basically same environment for both, and yet, that increasing similarity in environment, the Flynn Effect, the IQ gap has remained intact. Which means whatever counts for the gap is genetic and not environmental. The more and more similar the environment, the less and less of the difference can be due to the environment and the more and more it must be due to genes. So this 15 point gap surviving the these changes in environment, seems more and more likely to be genetic in origin.
So because this ‘Effect’ is the same across all populations and the gap didn’t close, that means it’s genetic. If the gap persisted even when IQs were rising 3 points per year, the B-W gap has still persisted, proving that it’s genetic.
That is why the Flynn Effect is irrelevant. This “Effect”, has been a slight upward trend in IQ, around 3 points per decade, which, in my opinion, has to do with the advent of better nutrition and an industrialized society. The rise in IQ started around 1880, almost perfectly coinciding with the industrial revolution in America. Along with a more industrialized society, it’s possible to give most citizens in the country good enough nutrition to where they are not iodine deficient (adding iodine to our salt boosted Americans IQs), as well as being deficient in zinc, iron, protein and certain B vitamins which the effects of not getting enough leads to the brain not growing to its full potential, which in turn leads to a lower IQ.
We all know what Rushton and Jensen thought of the “Flynn Effect”.
Critique only applies if you’re narrowly focused on some one country like the US where the B-W issue dominates everything.
Understanding the Flynn effect is extremely important when it comes to international comparisons since nutritional and development profiles can vary between them on the order of decades or in a few cases even centuries.
The Flynn Effect, assuming it’s real, has been acting completely uniformly in every population. Any country you ask, the rate of increase is 3 per decade.
This is simply not true. This is evident just from looking at OECD surveys of literacy and numeracy competence across age groups in different countries – almost zero between 50 and 20 year olds in the UK, a huge gap in South Korea.
That’s what I focus on, personally.
I do understand the “Flynn Effect”, i.e., better nutrition. It’s simple really. The gains in IQ started around the industrial revolution (correct me if I’m wrong).
Ah, I stand corrected. Can you grab me that source?
Ah, I stand corrected. Can you grab me that source?
Consult the age group data here (warning: big PD):
Click to access OECD_Skills_Outlook_2013.pdf
I plan to write a post about this pretty soon, incidentally.
pp. 272 contains the revelant table. Note that the S.D. in those tests is about 50.
The UK has a zero difference between the oldest and youngest group. Presumably, dysgenic decline has balanced out the Flynn Effect almost entirely. In South Korea, which went from Third World to almost-First World in one generation, the difference is almost 1 S.D.
The Flynn effect basically just showed that IQ differences were over-exaggerated- essentially that the difference between white and black IQs was -1SD, not -2SD, possibly even less.
The IQs in Sub-Saharan Africa still average about 70. It would appear, that Flynn, based on interviews I have seen, did not believe that Africa had gone through the effect that carries his name yet. He believed Americans/Europeans had experienced an 0.49 SD increase in IQ in the past 100 years, as Pumpkin Person indicated.
Blacks are currently 2SDs below whites, meaning that (2/0.49)(100)= 400 years.
They have the ability of Whites in the 1600s, however, they are screwed by malnutrition. They won’t be experiencing industrialization/Flynn effect for a good long while.
In the U.S., better nutrition has given blacks a very large Flynn effect, giving an IQ of 86 (slight white admixture). Assuming an SD of 16, and a European American average IQ of 102, that is exactly 1 SD. (1/0.49)x100 years= 200 years. Black Americans are going to have their own industrialization type experience soon, like whites did in the 1800s. Detroit is key to watch, blacks will run their own factories and do well, especially if Cruz or Sanders becomes President and brings back factories from East Asian and Kicks out the scab labor.
As Flynn said, they are “on the cusp of modernity”.
Flynn is interviewed in this. The presentation is slightly one sided and focuses more on statistics. No need to watch the whole thing to see the references in my post.
Thanks to Pumpkin Person for allowing me to essentially edit this post!
I brought that up in my linked article.
Right. With better nutrition they will get a boost, Lynn says that they can get a boost to 80. Though, they can’t do it themselves. Which way does the causality run? Can they not learn how to farm because of their low IQ? Or do they have low IQ because of horrible nutrition? I believe it’s due to evolution (obviously) that they can’t learn to farm because of their IQ. Along with malaria (which SCA developed to protect against malaria, and there is evidence that SCA depresses IQ as well) and parasitic load and lack of good nutrition, that’s why their IQs are low, around 70.
Though we can say, wouldn’t that be how they naturally are?
I don’t seem to understand. Blacks in America have a 1 SD advantage over their cousins due to white admixture (22 percent on average) as well as better nutrition, that those in Africa don’t get.
Lynn says that blacks in the South have IQs closer to 80 and have little to no white admixture. So, we can reason, that about 5 points of the increase from American blacks in comparison to Africans is due to white admixture, with the remaining 10 points due to nutrition.
I fail to comprehend what you’re saying. Are you saying that black IQs will get higher in the next 100 years? The evidence says otherwise.
This was one of the first videos I watched when I first jumped into this. IMO, Flynn is crazy to believe that Africa, as well as other under developed countries will match us in IQ as well as industrialization. They aren’t differences on g.
Click to access PAID-1999.pdf
It’s not a Jensen Effect, which are gains in g over time.
Let me explain your questions in your second to last paragraph;
I meant ACTUAL IQs, not genetic IQs. The actual IQ median/average of Sub-Saharan Africa is 70 right now, not 80. Therefore, the IQ gap between Sub-Saharan Nationals and African-Americans is NOT due to solely to white admixture, only partially.
Assuming that, say 100 years ago, African Americans were 0.49 SDs below their genetic IQ of 86 (let’s simplify and say that Sub-Saharans have Genetic IQs of 82, Northern Europeans have 102), that would mean 86- (0.49×16)= 78, therefore we could assume the AA IQ in 1900 was 78, while whites had 94. Simply subtract 4 to account for the sub-saharans full blackness, and you get 74, that’s still significantly above the actual median of 70. Therefore, assuming the Flynn effect has occured for two centuries, one could see that Sub-Saharans are extremely malnourished; ((4 /16))/(0.49)(100)= 51 years, meaning that Sub-Saharans have nutrition the same as Whites 151 years ago!(assuming the Flynn effect is constant) Wow!
Therefore 49/200= about 0.25. The intellectual gap between Sub-Saharans and African Americans, is attributed to Sub-Saharans going through 1/4 of the Flynn effect that African Americans have 16 IQ points- (16 IQ points in 200 years x 0.25)=12 IQ points + 70 IQ points= 82 IQ points. Now there is a 20 point genetic IQ gap between Sub-Saharans and whites, which is 20, and African Americans are 1/5 white, so 20/5=4, and 4+82=86, which is what we have.
Now of course, my rounding was sloppy, especially in 51/200= 0.25. That would indicate 86 is an overcalculation in proving AA IQs, however, your own quote that African Americans are “22% white” not 1/5 white, as I said, could compensate for that.
As for quotes about Detroit and relative civilization, my point was that African-Americans are 1SD below the white mean, and 1/0.49= 2 or roundabouts, so they are equivalent in intellect, but not malnutrition, to whites in the years just before 1800.
I believe I was wrong about Sub-Saharans, because they have gone through 0.25 of the Flynn effect (if they hadn’t their median IQ should be 66, not 70), therefore something else is at play here.
Which is what I said.
It hasn’t, seeing as the FE is better nutrition.
It’s not. We can see this from cultural achievements.
Here’s the cite:
http://isteve.blogspot.com/2013/02/henry-louis-gates-exactly-how-black-is.html
The only difference is Ancestry DNA which says 29 percent, but the other companies say around the same thing.
I admit I’m horrible, like really bad at math, so I take your word for it.
I was basing the idea that the Flynn effect has occurred for 200 years on the fact that the industrial revolution began about that time. I will maintain that until I do further research.
If the Flynn effect is not constant, then these are just very rough estimations.
That’s really weird and counterintuitive. I would certainly expect the difference to be smallest on the verbal component, but not altogether zero.
One very tentative hypothesis (apart from banal low sample size) is that verbal capacity isn’t strictly “limited” by brain size in children and young teens because brain growth in both groups outstrips the rate of word acquisition, but does set a hard boundary once they maturate.
And just to be clear, in the general population, we see huge differences in verbal IQ between people with big and small brains, but that’s because in the general population, both differences in brain size and differences in verbal IQ have a genetic component.
But in this study, because it focused on differences within pairs of identical twins, the differences in brain size were entirely nutritional. It seems that a difference in prenatal nutrition affects brain size and performance IQ, but has very little if any effect on verbal IQ (at least in childhood)
I suspect this is because in times of famine, evolution prioritized verbal IQ over performance IQ. This makes sense because humans are cultural animals. If we lose the performance IQ to figure out how to build shelter, we can use our verbal IQ to learn this skill from elders or from writings.
But if we lose our verbal IQ, we have to figure out everything out ourselves, and since this is an impossible task, we’d die.
Thus when nutrients are scarce, verbal IQ is preserved at the expense of performance IQ. .But when nutrients are plentiful,performance IQ comes roaring back and we see a massive Flynn effect
Mr. Person, would you mind sharing your thoughts on the significant differences that emerge when calculating FSIQ on the WAIS IV using the Canadian and American norms? Based on what Harrison et al. argue, Canadians are punished by around 4 FSIQ points when compared to their American friends, especially when it comes to groups in the lower-average range, and under the age of 35.
Given the discrepancy, it would appear that calculating Flynn effect for Canadians would be fruitless given the potential problems with the norming sample.
That’s a very good point. When I blogged about your WAIS-IV scores, I neglected to deduct points for the Flynn effect (WAIS-IV is about a decade old), however if your scores were reported in Canadian norms, this would cancel out any Flynn effect deduction.
A quick google gives me this page: https://www.nhs.uk/news/2008/02February/Pages/EarlynutritionbrainstructureandIQ.aspx
And the complete opposite effect is found:
“At adolescence, verbal IQ scores were significantly greater in the high-nutrient group than those of the standard-nutrient group. However, there was no difference between the groups in performance IQ.”
Maybe different nutrition is being talked about.