May 29, 2017

The Flynn Effect, Race, and IQ

For the last hundred years or so, each generation has scored higher than the previous one on IQ tests. The average IQ of populations has been rising. This is called “The Flynn Effect” and is named after James Flynn, a political philosopher and IQ researcher who helped discover the international nature of this trend.

Some people believe that the Flynn effect refutes the idea that racial IQ differences are partially caused by genetics. People making this argument often appeal to the fact that the IQ of African Americans today is equal to or higher than the IQ of White people in the past. This is true, but implies nothing about why Black people score worse than White people on IQ tests. Two groups differing genetically by X magnitude in some trait does not preclude the possibility of variation in the environment causing differences in the relevant trait of an even greater magnitude.

Consider a hypothetical garden in which two crops of corn, crop A and crop B, were planted in poor soil. Let’s suppose that corn stocks from crop A were, on average, 5 inches taller than corn stocks from crop B. Now, imagine that the bad soil of the garden was replaced with good soil and, as a result, the height of both crops increased by an average of 6 inches. Because both crop’s height increased by the same amount, the 5-inch gap between crop A and crop B remains.

What does this “Flynn Effect” in height tell us about the causes of the crop height gap? Nothing. This story is obviously fully consistent with the gap being entirely due to genes, the environment, or some combination of the two, even though crop B stocks of the “good soil generation” are taller than crop A stocks of the “poor quality soil generation”.

The same logic can be applied to individual differences: that the environment can cause large IQ differences between people over generations tells us nothing about why people within a single generation differ in IQ.

The economist Thomas Sowell does not commit the fallacious reasoning just outlined, but he does say this about the fact that Black American’s mean IQ score has risen by more than 15 points in the 20th century:

“Since the black-white difference in IQ is 15 points, this means that an even larger IQ difference has existed between different generations of the same race, making it no longer necessary to attribute IQ differences of this magnitude to genetics. In the half century between 1945 and 1995, black Americans’ raw test scores rose by the equivalent of 16 IQ points.” – Sowell (2001)

Even this seemingly conservative statement is incorrect. This is because the Flynn effect represents an increase in cognitive abilities which are different than the cognitive abilities that the races differ in.

To understand how we know this, we must first note that answering each question on an IQ test requires the mind to employ many cognitive abilities at once. For instance, a common question has people listen to a string of numbers read out loud and then has them repeat the number in the opposite order that they were heard in. To answer this question, a person must employ several abilities in order to save this information in their immediately accessible memory and reorganize the information so that they can repeat it back in reverse. This is an easy example, but even the most basic measures of pattern recognition require our minds to do multiple things in-order to produce an answer.

There are some extremely basic mental abilities, called “general intelligence” or “the G factor” which are involved in all the cognitive tasks included in IQ tests. There are other “item specific” cognitive abilities that are only needed to answer specific questions.

For instance, “general processing speed” may be part of general intelligence and may help people add numbers. However, people who can generally think equally quickly may still differ in how fast they can add.

We can measure the degree to which a given question requires general intelligence, as opposed to item specific cognitive abilities, by measuring how well scores on that question predict a person’s scores on all the other questions on an IQ test.

It has been found that there is a positive correlation between how well a question measures general intelligence and how much the races differ in it. This implies that racial IQ gaps are primarily gaps in general intelligence.

Studies have also shown that there is a negative correlation between how well a question measures general intelligence and how much that question was impacted by the Flynn effect. This suggests that the Flynn effect has consisted in a rise of item specific cognitive abilities.

Thus, the Flynn effect mostly (though perhaps not entirely) represents an increase in cognitive abilities which are different than the cognitive abilities which the races differ in.

Moreover, to the degree that both phenomena involve the same abilities, their causes are different. Researchers have determined that this is the case using the following logic: if the Flynn effect has the same causes as the Black/White IQ gap then the more a cognitive ability has been impacted by the Flynn effect the more it should differ racially.

For instance, suppose that IQ differences between the races and generations were both caused by the same nutritional deficiency. Suppose further that this nutritional deficiency has a very large impact on a person’s ability to recognize patterns but a very small impact on their vocabulary. If this is the case, then we would expect pattern recognition to differ more than vocabulary both between generations and between the races.

More generally, if the two gaps have the same cause, regardless of what that cause is, then the items which differ the most across generations should also differ the most across races.

Empirical studies have investigated this and found a negative correlation between the degree to which a cognitive ability is impacted by the Flynn effect and the degree to which it differs racially. This implies that, to the degree that the two phenomena involve the same abilities, they have different causes.

Even James Flynn, a well-known egalitarian in the race and IQ debate, has made the following statement:

“The magnitude of white/ black IQ differences on Wechsler subtests at any given time is correlated with the g loadings of the subtests; the magnitude of IQ gains over time on subtests is not usually so correlated; the causes of the two phenomena are not the same.” – Flynn 2013

In conclusion, the Flynn effect and racial intelligence differences have nothing to do with each other. Intelligence differences between races and between generations are largely gaps in different abilities, to the degree that they are gaps in the same abilities they are produced by different causes, and the existence of a large gain in intelligence over time has no a priori implications on the causes of racial intelligence differences.

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  • melonhead

    I’ve heard Flynn being praised by other IQ researchers as being an honest man, his lefty-ism notwithstanding.

    The idea of more g-correlated vs less g-correlated questions on IQ tests raises the question, though – why don’t people try to hone in on and make, just /more/ g-correlated questions?

  • Herbert Spencer

    The fact is that just as the average heights of people are increasing worldwide due to better nutrition, so too are average IQ scores increasing worldwide, for similar reasons. What I don’t expect to happen is that the average heights of all the populations on Earth will converge to the same height, just as I don’t expect the average IQ scores of all these populations to converge to the same score. Nevertheless, one might argue that past a certain threshold IQ inequalities between populations won’t matter as much as they do today (if, for example, everybody had an IQ score above 100). Of course, it remains to be seen whether or not the Flynn Effect is “powerful” enough for that to happen, and I suspect that for some populations it simply isn’t (say for Australian Aboriginals or African Pygmies).

  • Mark Martinson

    If anything the Flynn effect is evidence for hereditarianism. The gap is staying the same. If it were a real increase in intelligence, you’d expect the blacks to catch up over ttime but that’s not happening.

    • melonhead

      There’s a small, slow decrease in the gap. But it occurs to me that it might be due to race mixing! Ie, more white blood, but still counted as black. I don’t have any numbers, just a thought.

      • Mark Martinson

        I’ve also read that the Flynn effect is ending, at least in western countries.

      • Well, there has been a slow decrease if you start looking at around 1965. However, there was an increase in the B/W IQ gap from the 1910’s to the 1950’s, which is a period when the flynn effect was also occurring. So it has really been up and down over time while the flynn effect has been a fairly linear trend.

        Conveniently, from a rhetorical standpoint, the gap has gone up and down over the decades (a little, not a lot) but today the gap is roughly exactly what it was in the WW1 testing.

        • Mark Martinson

          With the dysgenic mating of blacks it’s unlikely to close and will probably increase. You know, there is nothing that the hereditarian perspective can’t explain. The environmentalists have to come up with an explantion for everything.

        • Sean Fielding

          1965, the year we dissidents often pick as the inflection point in the great decline (mainly because Immigration Act, but also acceleration in Civil Rights and start of hippy era). My guess is it also represents an inflection for miscegenation, If so, would support melonhead’s hypothesis

      • Rob

        IQ distribution by race/ethnicity:

             •   Ashkenazi Jews = 115
             •   East Asians = 106
             •   Whites = 100
             •   South East Asians = 87
             •   Non-White Hispanics = 86
             •   American Blacks = 85 (average 24% White admixture)
             •   Middle East and North Africans = 84
             •   Sub-Saharan Blacks = 67 (Only 2% of Whites score this low)
             •   Australian Aborigines = 62

    • Rob

      “The gap is staying the same. If it were a real increase in intelligence, you’d expect the blacks to catch up over ttime but that’s not happening.”

      In the 20 year period from 1994-2014 the Black-White difference increased on both the verbal and math SATs. On the reading test, it rose from .91 to .96 standard deviations. On the math test, it rose from .95 to 1.03 standard deviations.

  • Mark Martinson

    Flynn denies the black/white IQ gap is genetic. Does he deny the Ashkenaiz Jewish/Aborigine gap is genetic?

    • melonhead

      He doesn’t deny that it /might be/, he just holds out the optimistic hope that it will prove to have some other, fixable cause. He’s said that the Flynn Effect leaves a crack open, something like that.

      • Mark Martinson

        I should have been more careful. Flynn has said (in his recent book) that it’s more likely than not that the black/white IQ gap is entirely environmental. Funny, no politician would say that.

      • BooBoo65

        I would suspect he is in the camp of thinking it’s best to not talk about it and he puts on the environmentalist front. I just can’t imagine any serious IQ researcher, with all the evidence we have, still thinking so much of it is related to the environment.

        There is a lot of pressure if you come out of the closet on that and he probably just doesn’t think it’s worth it.

        • Grey

          I just can’t imagine any person of actual intelligence taking IQ seriously unless it is noticeably below average.

          • Rob

            What about life? Is that an IQ test? Why are Blacks always unsuccessful?

          • Grey

            Demonstrate that to be true and then we have a conversation starter.

          • Rob

            Name a single contribution from sub-Saharan Africans to the world.

            Are societies more safe and prosperous if they are more White, or more Black?

            Do you dispute that Blacks have small brains and low IQs?

            Whites are only 10% of the world’s population, yet are the most industrious, ingenious, and innovative race the world has known. Whites have formed nations, built civilizations, assumed and administrated power, created the Renaissance, the Age of Discovery, the Industrial Revolution, automation, technology, the space program which landed men on the moon and launched probes exploring beyond the solar system, discovered electricity, created wonder drugs and architecture and have harnessed nuclear power, have unlocked the secrets of DNA and relativity, created computer science and the internet age…… sub-Saharan Africans still cannot even feed themselves.

            No pre-contact sub-Saharan African society ever created a written language, or weaved cloth, or forged steel, invented the wheel or plow, or devised a calendar, or code of laws, or any social organization, or formal religion, or system of measurement, or math, or built a multi-story structure or bridge or sewer, or infrastructure of any kind, and they never harnessed a river, or even drilled well or irrigated, or built a road or railway or sea-worthy vessel, they never domesticated animals, or exploited underground natural resources, or produced anything that could be considered a mechanical device.

            Blacks are the only race incapable of caring for themselves. Whites still have to provide food, medical, financial and engineering aid to Africans. They couldn’t survive without White charity. Blacks became an out-of-control invasive species after Whites domesticated them.

            Blacks lived alone in sub-Saharan Africa, a vast continent with temperate climates and abundant resources for 60,000 years; so they cannot blame racism, poverty, imperialism or anything else for their failures. How could they live with all that shoreline and never contemplate putting a sail on a ship like every other culture did?

            Blacks are the oldest race, they had a huge head-start so they should be the most advanced race; but they are the least advanced race. And in fact they never did develop until they were domesticated by Whites.

            19 of the 20 poorest countries are sub-Saharan African (Haiti). There has never been a successful Black country. No modern creations or civilization exists in sub-Saharan Africa that was not brought there by Whites.

            There are no White Third-World nations, but all Black ones are.

            Put Whites on an island and you get England; put Asians on an island and you get Japan; put Blacks on an island and you get Haiti.

            Nowhere Blacks live are they considered achievers. In fact they are universally viewed as unproductive and disruptive to society.

            Simply, life is an IQ test.

            Sub-Saharan Africans have never made a contribution to the world. Blacks can only achieve either because they are mixed with White genes or because they reside in White societies. For every one gifted Black there are eight gifted Whites. 80% of gifted Blacks are mixed-race.

            Today there are 738 million Europeans and 1.2 billion Africans. In 2050, according to the latest U.N. projections, Europe’s population will have dipped to 707 million, while Africa’s population will be 2.4 billion. By 2100, half of all children on earth will be African. On current trends, within 35 years, 1 in every 4 people will be sub-Saharan African. By 2100, there will be 4.4 billion Africans – two of every five human beings overall — and Europe’s population will be just 646 million.

            The 41 nations of sub-Saharan Africa produce no more wealth than the tiny country of Belgium, which has only 1/45 the population. The entire continent of Africa produces less than 1% of the world’s manufactured goods. Of all of the region’s economic production, White-run South Africa accounts for three-quarters of it. That Whites are only 8% of South Africa’s population demonstrates how productive and industrious Whites are that so relative few can carry the load for so many unproductive Blacks.

            Blacks are unable to achieve within their own race because not enough of them are smart enough to even build a sufficient infrastructure to allow for the Black intellectual elite to achieve. If allowed to become too numerous they destroy previously thriving and safe White cities.

            Blacks cannot achieve on their own without the intervention of Whites giving them all the things they could never produce or maintain themselves. Without the continuous intervention of charity into Black Africa they could not even maintain what they have been given.

            All current Black civilization is in fact transplanted White civilization. There is no Black society on Earth that has independently developed and maintained its own technological way of life. All of the Black nations with the highest GDPs benefited from White-created enterprise to exploit their natural resources.

            Some groups succeed all the time, everywhere. Some have never succeeded anywhere. Blacks are the oldest race so they should be the most advanced, but they have never been successful anywhere. But civilization didn’t begin until humans evolved from Blacks by hybridizing with the large-brained Neanderthals which produced a modern human with an increase in cranium capacity and a heavier, more developed brain. Blacks are also the only race without MCPH1 microcephalin which produces increased brain volume density.

            This is why Blacks seethe with jealousy and hatred of Whites yet can’t seem to stay away because they want what we create and maintain, no matter if they deserve it or not. They want our peaceful and clean neighborhoods, our law and order, our technology and science, our school systems, our inventions, the jobs we create, the food we grow, the transportation we invent, the entertainment we provide….. Blacks hate us but can’t live without us. That’s why they demand that we take care of them and give them special rights and privileges that we don’t grant ourselves, just to compensate for their inability at living in a modern and technologically-advanced civilization.

            Slavery was the best thing to happen to Blacks. After defeating George Foreman for the heavyweight title in Zaire (now Congo), Muhammad Ali returned to the United States where he was asked by a reporter, “Champ, what did you think of Africa?” Ali replied, “Thank God my granddaddy got on that boat.”

            There hasn’t been a single contribution from sub-Saharan Africans to the world. Show me any community, city or state that is predominantly inhabited and run by Blacks anywhere in the world that is equal or superior to a comparable White one. By their fruits ye shall know them. Show me the fruits of that intelligence.

            “There is no firm reason to anticipate that the intellectual capacities of peoples geographically separated in their evolution should prove to have evolved identically. Our wanting to reserve equal powers of reason as some universal heritage of humanity will not be enough to make it so.” Dr James Watson

          • Grey

            Essentially whites pillaged and raped other countries and decided to “be the first asshole”. They made other discoveries their own, stole other inventions and lauded them as “white creations”. Lmao.

          • Rob

            “Essentially whites pillaged and raped other countries…….”

            What did Whites steal from Blacks??

          • Rob

            Black-White IQ Distribution:

            For a graphical representation of the racial IQ gap Google: racial IQ bell curve

            Percentages below are from a cumulative percentages graph for readability:

            Blacks:
                             5% above 110 IQ
                             16% above 100 IQ
                             40% above 90 IQ
                             70% above 80 IQ
                             30% below 80 IQ
                             18% below 75 IQ
                             10% below 70 IQ

            Whites:
                             10% above 120 IQ
                             18% above 115 IQ
                             27% above 110 IQ
                             40% above 105 IQ
                             50% above 100 IQ
                             60% below 105 IQ
                             35% below 95 IQ
                             15% below 85 IQ

            So, the smartest 16% of Blacks are as intelligent as smartest 50% of Whites. 80% of Blacks score at or below the “low functioning” category.

            The least intelligent ten percent of Whites have IQs below 80; forty percent of Blacks have IQs that low.

            Only one Black in six is more intelligent than the average White; five Whites out of six are more intelligent than the average Black.

            These differences show in every test of general cognitive ability that anyone, of any race or nationality, has yet been able to devise. And they are reflected in countless everyday situations, “Life is an IQ test.”

            Further, only one-in-3.5 million (.00003%) African Blacks have an IQ of 140 or higher (genius level). But one-in-83 (1.2%) U.S. Whites is a genius. Therefore the per capita genius rate for U.S.-resident Whites is 41,000 times higher than it is for African Blacks.

            As the New York Times put it, “…the difference in I.Q. points between the groups is quite significant. It means that the top sixth of Blacks score only as well on I.Q. tests as do the top half of Whites.”

            Black females have higher IQs than Black males. Black female IQ is 2.4 points higher than Black male IQ. There are twice as many Black females as Black males with IQs over 120 and five times as many Black females as Black males with IQs over 140.

          • Rob

            Black-White SAT Score Gap by Year:

                   Year              White             Black               Gap
                   1986              1038               839                 199
                   1990              1031               849                 185
                   1996              1052               857                 195
                   2000              1060               859                 201
                   2005              1061               863                 197
                   2010              1063               855                 208

            Source: U.S. Dept. of Education, Digest of Education Statistics, 2012

            Note that there is no closing of the large and persistent so-called “achievement gap”.

            In the 20 year period from 1994-2014 the Black-White difference increased on both the verbal and math SATs. On the reading test, it rose from .91 to .96 standard deviations. On the math test, it rose from .95 to 1.03 standard deviations.

            In 2015 only 16% of Blacks scored 1550 or higher, the threshold the College Board calls the “college and career readiness” level.

            This racial achievement gap is so significant that colleges give a “race bonus” of 230 points to Blacks and penalize Asians by 50 points to try to keep it even.

            Frey and Detterman (2003) analyzed the correlation of SAT scores with intelligence test scores. They found SAT scores to be highly correlated with general mental ability, or g (r=.82 in their sample).

            Abstract

            This research established the relationship between SAT and g, as well as the appropriateness of the SAT as a measure of g, and examined the SAT as a premorbid measure of intelligence. In Study 1, we used the National Longitudinal Survey of Youth 1979. Measures of g were extracted from the Armed Services Vocational Aptitude Battery and correlated with SAT scores of 917 participants. The resulting correlation was.82 (.86 corrected for nonlinearity). Study 2 investigated the correlation between revised and recentered SAT scores and scores on the Raven’s Advanced Progressive Matrices among 104 undergraduates. The resulting correlation was.483 (.72 corrected for restricted range). These studies indicate that the SAT is mainly a test of g. We provide equations for converting SAT scores to estimated IQs; such conversion could be useful for estimating premorbid IQ or conducting individual difference research with college students.

            Frey MC, Detterman DK.

            PMID: 15147489 [PubMed – indexed for MEDLINE]

            ~~~~~

            New York Times, 2003:

            The SAT captures more than a narrow range of skills, important only in the first year or two of college. Large-scale meta-analyses by researchers at the University of Minnesota have found that SAT performance is as good of a predictor of overall college grade point average as it is of freshman grade point average, and Vanderbilt researchers David Lubinski and Camilla Benbow have documented that the SAT predicts life outcomes well beyond the college years, including income and occupational achievements.

            Furthermore, the SAT is largely a measure of general intelligence. Scores on the SAT correlate very highly with scores on standardized tests of intelligence, and like IQ scores, are stable across time and not easily increased through training, coaching or practice. SAT preparation courses appear to work, but the gains are small — on average, no more than about 20 points per section.

            ~~~~~~~

            ACT Scores by Race:

                   Year              White             Black               Asian
                   2009              22.2               16.9                 23.2
                   2010              22.3               16.9                 23.4
                   2011              22.4               17.0                 23.6
                   2012              22.4               17.0                 23.6
                   2013              22.2               16.9                 23.5
                  
            Source: ACT, Inc.

            ~~~~~

            Percent by Race Reaching the SAT College and Career Readiness Benchmark:

                             15% = Black
                             24% = Non-White Hispanic
                             35% = Native American
                             53% = White
                             56% = Asian               

            Source: The College Board, 2014

          • Rob

            Compared to Blacks, Whites’ brains:

                 •   are 7% larger (1438cc versus 1343cc)
                 •   are 100 grams heavier
                 •   have deeper fissuration in the frontal and occipital regions
                 •   have more complex convolutions and larger frontal lobes
                 •   have more pyramidal neurons
                 •   have 16% thicker supra-grandular layer
                 •   react faster on mental chronometry tests
                 •   have 600 million more neurons (each carries about 600 billion synapses, which each carry one bit of cortical information)

            Genes contribute to about 90% of the individual variation of brain size.

            Asian, White, and Black brains can be reliably differentiated by examining the surface configuration.

            Blacks are the only racial group with no DNA from the large-brained Neanderthals, and also the only race without the derived form of MCPH1 microcephalin called haplogroup D which produces increased brain volume.

            The correlation between brain size and IQ across 25 primate species is 0.77 (where 1.0 indicates that monozygotic twins have no variance in IQ and 0 indicates that their IQs are completely uncorrelated).

            Larger brains contain more neurons and synapses and process information faster. By adulthood, East Asians average 1 cubic inch more cranial capacity than Whites who average 5 cubic inches more than Blacks.

            The average White brain is 1438cc while the average Black brain is 1343cc, or 93% of the average White brain. The heritability of brain size is extremely strong at 0.90 and not one study to date has shown larger brain size for Blacks. The White and Asians brain also has a higher degree of fissuring (higher complexity) in the cerebral cortex of their brains, where abstract and conceptual thought is performed.

            There are also racial differences in brain shape, fissuration, number of pyramidal neurons and supra-grandular layer thickness. The depth of fissuration is related to superior intelligence and the brains of Whites have deeper fissures in the frontal and occipital regions. The supra-grandular layer of Blacks’ brains is 16% smaller than it is for Whites’ brains.

            Based on studies of brain weight at autopsy, endocranial volume of empty skulls, head size measurements by the U.S. military and NASA, and two dozen MRI volumetric studies Blacks’ brain size is 7% smaller than Whites’, and 8% smaller than Asians’. There is a correlation of brain size with IQ of about 0.40 and that these racial differences in brain size are present at birth. Genes contribute to about 90% of the individual variation of brain size.

            In addition to brain size are differences in brain shape, fissuration, number of pyramidal neurons and supra-grandular layer thickness. The depth of fissuration is related to superior intelligence and the brains of Whites have deeper fissures in the frontal and occipital regions. The supra-grandular layer of Blacks’ brains is 16% smaller than it is for Whites’ brains.

            The average human brain contains 86 billion neurons. Whites, on average, have 600 million more neurons than Blacks. Each neuron carries about 600 billion synapses, each of which carries, as a minimum, one bit of cortical information.

            Blacks are the only racial group with no DNA from the large-brained Neanderthals, and also the only race without the derived form of MCPH1 microcephalin called haplogroup D which produces increased brain volume.

            Even before birth, population group differences in average brain size are found from the ninth week of intrauterine life with White fetuses averaging larger brain cases and smaller faces Black fetuses, with the differences becoming more prominent over the course of fetal development.

            Weighing brains at autopsy, Whites averaged heavier brains than Blacks and had more complex convolutions and larger frontal lobes. Subsequent studies have found an average Black–White difference of about 100 g. Studies have found that the more White admixture (judged independently from skin color), the greater the average brain weight in Blacks. In a study of 1,261 American adults, Ho et al. (1980) found that 811 White Americans averaged 1,323 g and 450 Black Americans averaged 1,223 g. Since the Blacks and Whites were similar in body size, differences in body size cannot explain away the differences in brain weight.

            The same three-way pattern of race differences has been found using the simplest culture-free cognitive measures such as reaction time tasks, which 9- to 12-year-old children perform in less than 1 s. Lynn (2006) found that East Asian children from Hong Kong and Japan were faster than European children from Britain and Ireland, who in turn were faster than African children from South Africa. Using similar tasks, this pattern of racial differences was also found in California (Jensen, 1998; Rushton & Jensen, 2005). Within each group, the children with higher IQ scores perform faster those with lower scores.

            Race differences start in the womb. Blacks are born earlier and grow quicker than Whites and Asians. The three-way race pattern occurs in milestones such as sexual maturity, family stability, crime rates, and population growth.

            Black babies mature more quickly than White babies, while Asian babies mature more slowly. Black babies in a sitting position are more able to keep their heads up and backs straight from the start. White babies often need six to eight weeks to do these things. It is unlikely that social factors could produce these differences. A basic law of biology shows that longer infancy is related to greater brain growth.

            Black babies spend the least time in the womb. In America, 51% of Black children have been born by week 39 of pregnancy compared with 33% of White children. In Europe, Black babies of even professional mothers are born earlier than White babies.

            Black children sit, crawl, walk, and put on their own clothes earlier than Whites or Asians. The findings are measured by such tests as Bayley’s Scales of Mental and Motor Development and the Cambridge Neonatal Scales.

            Asian children, on the other hand, mature more slowly than do White children. Asian children often do not walk until 13 months. Walking starts at 12 months for white children and 11 months for Black children.

            ~~~~~~~~~~

            Meta-analysis of associations between human brain volume and intelligence differences

            AUTHORS: Pietschnig, Penke, Wicherts, Zeiler, Voracek

            ABSTRACT: “By means of a systematic review of published studies and unpublished results obtained by personal communications with researchers, we identified 88 studies examining effect sizes of 148 healthy and clinical mixed-sex samples. Our results showed significant positive associations of brain volume and IQ.”

            2015, October

            PMID: 26449760

            ~~~~~~~~

            Brain mass differences between racial groups in the US

            Jensen (1998) summarizes the brain mass findings from the Case-Western Reserve (1980) study (N= 811 W, 450 B). An age matched and height adjusted B-W differences of ~100g (~.78SD) was found, which is commensurate with the findings of Bean (1906), Mall (1909), Pearl (1934), and Vint (1934) as described in Rushton and Ankney (2009). Holloway (2002) found a B-W difference of 63 grams (N = 1,391 W; 615 Black). Similar findings have been found based in imaging studies (see 5). In their study, Isamah, et al. (2010) found that African Americans have 1 SD less total cerebrum volume than European Americans.

            ~~~~~~~~~~~~~~~

            Contrary to most purely environmental theories, racial differences in brain size show up early in life. Data from the U.S. National Collaborative Perinatal Project on 19,000 Black children and 17,000 White children showed that Black children had a smaller head perimeter at birth and, although Black children were born shorter in stature and lighter in weight than White children, by age 7 ‘catch-up growth’ led Black children to be larger in body size than White children. However, Blacks remained smaller in head perimeter (Broman et al., 1987). Further, head perimeter at birth, 1 year, 4 years, and 7 years correlated with IQ scores at age 7 in both Black and White children (r = 0.13 to 0.24).

            ~~~~~~~~~~~~~~

            Brain Size Differences. Studies using magnetic resonance imaging (MRI) find a correlation of brain size with IQ of about 0.40. Larger brains contain more neurons and synapses and process information faster. Race differences in brain size are present at birth. By adulthood, East Asians average 1 cubic inch more cranial capacity than Whites who average 5 cubic inches more than Blacks.

            “Neither the existence nor the size of race differences in IQ are a matter of dispute, only their cause,” write the authors. The Black-White difference has been found consistently from the time of the massive World War I Army testing of 90 years ago to a massive study of over 6 million corporate, military, and higher-education test-takers in 2001.

            “Race differences show up by 3 years of age, even after matching on maternal education and other variables,” said Rushton. “Therefore they cannot be due to poor education since this has not yet begun to exert an effect. That’s why Jensen and I looked at the genetic hypothesis in detail. We examined 10 categories of evidence.”

            1. The Worldwide Pattern of IQ Scores; East Asians average higher on IQ tests than Whites, both in the U. S. and in Asia, even though IQ tests were developed for use in the Euro-American culture. Around the world, the average IQ for East Asians centers around 106; for Whites, about 100; and for Blacks about 85 in the U.S. and 70 in sub-Saharan Africa.

            2. Race Differences are Most Pronounced on Tests that Best Measure the General Intelligence Factor (g); Black-White differences, for example, are larger on the Backward Digit Span test than on the less g loaded Forward Digit Span test.

            3. The Gene-Environment Architecture of IQ is the Same in all Races, and Race Differences are Most Pronounced on More Heritable Abilities; Studies of Black, White, and East Asian twins, for example, show the heritability of IQ is 50% or higher in all races.

            4. Brain Size Differences; Studies using magnetic resonance imaging (MRI) find a correlation of brain size with IQ of about 0.40. Larger brains contain more neurons and synapses and process information faster. Race differences in brain size are present at birth. By adulthood, East Asians average 1 cubic inch more cranial capacity than Whites who average 5 cubic inches more than Blacks.

            5. Trans-Racial Adoption Studies; Race differences in IQ remain following adoption by White middle class parents. East Asians grow to average higher IQs than Whites while Blacks score lower. The Minnesota Trans-Racial Adoption Study followed children to age 17 and found race differences were even greater than at age 7: White children, 106; Mixed-Race children, 99; and Black children, 89.

            6. Racial Admixture Studies; Black children with lighter skin, for example, average higher IQ scores. In South Africa, the IQ of the mixed-race “Colored” population averages 85, intermediate to the African 70 and White 100.

            -June 2005, Psychology, Public Policy and Law, a journal of the American Psychological Association

            ~~~~~~~~~~~~~~

            According to a new study, just published in the University of California Los Angeles (UCLA) newsroom, scientists have definitively found the genes which control brain size and intelligence.

            Dozens of studies have found race differences in brain size, whether measured by MRI, endocranial volume, brain weight at autopsy or external head size (with or without corrections for body size).

            Most were carried out on the three major races of East Asians, Europeans, and Africans. Averaging all the data, the following figures have emerged: Brain size average for East Asians = 1364cm; Whites = 1347cm; and Blacks = 1267cm.

            The overall mean for East Asians was 17cm more than for Whites and 97cm more than for Blacks.

            Since every cubic centimeter of brain tissue contains millions of brain cells and billions of synapses, the race differences in brain size help to explain the race differences in IQ.

            The latest overview, billed as the “world’s largest brain study to date,” saw a team of more than 200 scientists from 100 institutions worldwide collaborate to map the human genes that boost or sabotage the brain’s resistance to a variety of mental illnesses and Alzheimer’s disease.

            Additionally, the study (also published in the journal Nature Genetics), found new genes which control “differences in brain size and intelligence.”

            “We searched for two things in this study,” said senior author Paul Thompson, professor of neurology at the David Geffen School of Medicine at UCLA and a member of the UCLA Laboratory of Neuro Imaging.

            “We hunted for genes that increase your risk for a single disease that your children can inherit. We also looked for factors that cause tissue atrophy and reduce brain size, which is a biological marker for disorders like schizophrenia, bipolar disorder, depression, Alzheimer’s disease and dementia.”

            Three years ago, Thompson’s lab partnered with geneticists Nick Martin and Margaret Wright at the Queensland Institute for Medical Research in Brisbane, Australia, and with geneticist Barbara Franke of Radboud University Nijmegen Medical Centre in the Netherlands.

            The four investigators recruited brain-imaging labs around the world to pool their brain scans and genomic data, and Project ENIGMA (Enhancing Neuro Imaging Genetics through Meta-Analysis) was born.

            “Our individual centers couldn’t review enough brain scans to obtain definitive results,” said Thompson, who is also a professor of psychiatry at the Semel Institute for Neuroscience and Human Behavior at UCLA.

            “By sharing our data with Project ENIGMA, we created a sample large enough to reveal clear patterns in genetic variation and show how these changes physically alter the brain.”

            ~~~~~~~~~~~~~~~

            Recent reviews (by Nisbett et al. (2012b) and Mackintosh (2011)) confirm current data does show an average difference in brain size and head-circumference between American Blacks and Whites.

            Brain size is found to have a correlation of about .35 with intelligence and cites studies showing that genes may account for as much as 90% of individual variation in brain size, concluding that race differences in average brain size could be an important argument for genetic contribution to racial IQ gaps.

            – Considerations Relating to the Study of Group Differences in Intelligence, Earl Hunt1 and Jerry Carlson, The University of Washington
            – American Psychologist, Vol 67(6), Sep 2012, 503-504

            On the outside, there’s not a lot of difference between Black heads and White ones. There is a slight difference, however, with Whites having the larger heads. But the big difference is in the size of the brain. Blacks have thicker skulls, which means that a higher percentage of their head is bone instead of brain.

            Blacks are the only race without the derived form of MCPH1 microcephalin called haplogroup D which appeared about 37,000 years ago and is associated with increased brain volume.

            Empirical data obtained from brain weight at autopsy, endocranial volume of empty skulls, head size measurements by the U.S. military and NASA, and two dozen MRI volumetric studies have shown that brain volumes average 1427 cubic centimeters for Whites, but only 1361 cubic centimeters for Blacks.

            In weight measurements, the brains of African Blacks were found to weigh an average of 1157 grams, whereas those of pure Whites weighed an average of 1323 grams. The brains of US-resident Blacks, who have a bit of White mixture in their genetic makeup, average 1223 grams in weight.

            That 100-gram weight difference, between White Americans and US-resident Blacks, corresponds to an approximate 600 million neuron advantage for Whites. In 600 million neurons, there are about 600 billion synapses, each of which carries, as a minimum, one bit of cortical information.

            Also, Whites have a larger genus to splenium ratio (front to back part of corpus callosum), which indicates that Whites probably have more activity in the frontal lobes which are thought to be the seat of intelligence. One study found that White cerebrums exhibited 14% more sulsification, or fissuring, as compared with those of Blacks. So, not only are White brains larger, they are also significantly more complex.

            Blacks also have considerably smaller frontal lobes. Frontal lobes are responsible for planning complex cognitive behavior, personality expression, decision making and moderating social behavior.

            This is a genetic trait because even malnourished Asians from poor countries have a larger brain on average than well fed blacks from western countries.

            Sources:

            Willerman et al. (1991) Using MRI obtained r’s ranging from .26 to .56 between IQ and the size of specific brain structures and an overall r of .38 between full-scale IQ and gray matter volume when body size is controlled for. Replications by Raz et al. (1993) and Wickett, Vernon and Lee (1994) found correlations between IQ and brain size of .41 and .47-49. Egan et al. (1994) found an r of .32 between IQ and brain size in a sample whose SD for IQ was 9.3.

            Beals, K. L., Smith, C. L., & Dodd, S. M. (1984). Brain size, cranial morphology, climate, and time machines. Current Anthropology 25, 301–330.

            Jensen, A. R. (1998). The g Factor. Westport, CT: Praeger.

            Rushton, J. P. & Ankney, C. D. (1996). Brain size and cognitive ability: Correlations with age, sex, social class, and race. Psychonomic Bulletin and Review, 3, 21-36.

            Ho, K. C., Roessmann, U., Straumfjord, J. V., & Monroe, G. (1980). Analysis of brain weight: I and II. Archives of Pathology and Laboratory Medicine 104, 635–645.

            Johnson F. W. & Jensen (1994). Race and sex differences in head size and IQ. Intelligence 18: 309–33

            Rushton JP. (1997). Cranial size and IQ in Asian Americans from birth to age seven. Intelligence 25: 7–20.

            Rushton JP (1991). Mongoloid-Caucasoid differences in brain size from military samples [and NASA]. Intelligence 15: 351–9.

            Cranial Capacities:

            Study                    Black               White                Asian             Black/White

            Ho et al., 1980          1267                1370                                   .92

            Gould, 1981              1356                1426                 1426              .95

            Beals, 1984             1276                1362                 1380              .93

            Herskovits, 1993         1295                1421                 1451              .91

            Ruston (Army) 92         1346                1361                 1403              .98

            Ruston (ILO), 1994       1228                1284                 1312              .95
                        

          • Rob

            Google: National IQ Congo

            ….then: IQ Koko the gorilla

            LOL

            IQ correlates strongly to job performance, increased wealth, increased income, economic growth, livability in a U.S. state, cooperation, life expectancy and infant mortality.

            It is estimated that a minimum IQ of 90 is required just to maintain a technological society.

            The more White a society is the more successful (safe and prosperous) it is.

            The following intelligence scores came from work carried out earlier this decade by Richard Lynn, a British psychologist, and Tatu Vanhanen, a Finnish political scientist, who analysed IQ studies from 113 countries, and from subsequent work by Jelte Wicherts, a Dutch psychologist. Lynn and Vanhanen benchmarked their IQ results so that Britain is 100. America scores 98 on this scale, and the world average is 90. IQ`s are assumed to form a normal probability distribution (“bell curve”) with the standard deviation set at 15.

            National IQ correlates at 0.73 with living standard.

            Each 10 point increase in IQ generally doubles economic growth, assuming the country has a market economy:

                      •   108      Singapore
                      •   106      South Korea
                      •   105      Japan
                      •   105      China
                      •   102      Italy
                      •   101      Iceland
                      •   101      Mongolia
                      •   101      Switzerland
                      •   100      Austria
                      •   100      Luxembourg
                      •   100      Netherlands
                      •   100      Norway
                      •   100      United Kingdom
                      •   99        Belgium
                      •   99        Canada
                      •   99        Estonia
                      •   99        Finland
                      •   99        Germany
                      •   99        New Zealand
                      •   99        Poland
                      •   99        Sweden
                      •   98        Andorra
                      •   98        Australia
                      •   98        Czech Republic
                      •   98        Denmark
                      •   98        France
                      •   98        Hungary
                      •   98        Latvia
                      •   98        Spain
                      •   98        United States
                      •   97        Belarus
                      •   97        Malta
                      •   97        Russia
                      •   97        Ukraine
                      •   96        Moldova
                      •   96        Slovakia
                      •   96        Slovenia
                      •   96        Uruguay
                      •   95        Israel
                      •   95        Portugal
                      •   94        Armenia
                      •   94        Georgia
                      •   94        Kazakhstan
                      •   94        Romania
                      •   94        Vietnam
                      •   93        Argentina
                      •   93        Bulgaria
                      •   92        Greece
                      •   92        Ireland
                      •   92        Malaysia
                      •   91        Brunei
                      •   91        Cambodia
                      •   91        Cyprus
                      •   91        Lithuania
                      •   91        Thailand
                      •   90        Albania
                      •   90        Bosnia
                      •   90        Chile
                      •   90        Croatia
                      •   90        Kyrgyzstan
                      •   90        Turkey
                      •   89        Cook Islands
                      •   89        Costa Rica
                      •   89        Laos
                      •   89        Mauritius
                      •   89        Serbia
                      •   89        Suriname
                      •   88        Ecuador
                      •   88        Mexico
                      •   88        Samoa
                      •   87        Azerbaijan
                      •   87        Bolivia
                      •   87        Brazil
                      •   87        Guyana
                      •   87        Indonesia
                      •   87        Iraq
                      •   87        Myanmar
                      •   87        Tajikistan
                      •   87        Turkmenistan
                      •   87        Uzbekistan
                      •   86        Kuwait
                      •   86        Philippines
                      •   86        Seychelles
                      •   86        Tonga
                      •   85        Cuba
                      •   85        Eritrea
                      •   85        Fiji
                      •   85        Kiribati
                      •   85        Peru
                      •   85        Trinidad and Tobago
                      •   85        Yemen
                      •   84        Afghanistan
                      •   84        Bahamas
                      •   84        Belize
                      •   84        Colombia
                      •   84        Iran
                      •   84        Jordan
                      •   84        Marshall Islands
                      •   84        Micronesia
                      •   84        Morocco
                      •   84        Nigeria
                      •   84        Pakistan
                      •   84        Panama
                      •   84        Paraguay
                      •   84        Saudi Arabia
                      •   84        Solomon Islands
                      •   84        Uganda
                      •   84        United Arab Emirates
                      •   84        Vanuatu
                      •   84        Venezuela
                      •   83        Algeria
                      •   83        Bahrain
                      •   83        Libya
                      •   83        Oman
                      •   83        New Guinea
                      •   83        Syria
                      •   83        Tunisia
                      •   82        Bangladesh
                      •   82        Dominican Republic
                      •   82        India
                      •   82        Lebanon
                      •   82        Madagascar
                      •   82        Zimbabwe
                      •   81        Egypt
                      •   81        Honduras
                      •   81        Maldives
                      •   81        Nicaragua
                      •   80        Barbados
                      •   80        Bhutan
                      •   80        El Salvador
                      •   80        Kenya
                      •   79        Guatemala
                      •   79        Sri Lanka
                      •   79        Zambia
                      •   78        Congo
                      •   78        Nepal
                      •   78        Qatar
                      •   77        South Africa
                      •   76        Cape Verde
                      •   76        Congo
                      •   76        Mauritania
                      •   76        Senegal
                      •   74        Mali
                      •   74        Namibia
                      •   73        Ghana
                      •   72        Tanzania
                      •   71        Central African Republic
                      •   71        Grenada
                      •   71        Jamaica
                      •   71        St Vincent, Grenadines
                      •   71        Sudan
                      •   70        Antigua, Barbuda
                      •   70        Benin
                      •   70        Botswana
                      •   70        Rwanda
                      •   70        Togo
                      •   69        Burundi
                      •   69        Cote d’Ivoire
                      •   69        Ethiopia
                      •   69        Malawi
                      •   69        Niger
                      •   68        Angola
                      •   68        Burkina Faso
                      •   68        Chad
                      •   68        Djibouti
                      •   68        Somalia
                      •   68        Swaziland
                      •   67        Dominica
                      •   67        Guinea
                      •   67        Guinea-Bissau
                      •   67        Haiti
                      •   67        Lesotho
                      •   67        Liberia
                      •   67        Saint Kitts
                      •   67        Sao Tome
                      •   66        Gambia
                      •   64        Cameroon
                      •   64        Gabon
                      •   64        Sierra Leone
                      •   64        Mozambique
                      •   62        Saint Lucia
                      •   59        Equatorial Guinea

          • Rob

            Name a single contribution from sub-Saharan Africans to the world.

          • Grey

            I like how you specifically refer to “sub-Saharan” Africans instead of just Africans as a whole.
            You moronic new-aged millenial white boys are so fragile it’s hilarious.

            Whites have been colonizing and trying to get the wealth and resources of other peoples and lands for centuries. This includes human resources, like trying to access the women of other races. This is because they have an inherent malevolence. They are like a cancer that spreads, attacks, infiltrates, takes over, and then destroys through genocide. They are most pissed off when somebody is doing fine or better than them and they are excluded. It was the way of the world back when the Silk Road was benefitting mainly East Asia, India, the Middle East, and Africa. Whites felt they were “excluded”, so they had to come crash the party and kill everyone and steal everything. It was the same with China. Whites wanted to force China to open its borders so they could march in and steal all the wealth while trying to trick Chinese businesspeople into accepting unfair trade relations.
            Whites cannot stand it when some other race of peoples have a tight knit community or nation that operates independently of them. It’s no wonder whites hate their jew cousins so much. They are exactly like each other. They are parasitic.

            Rape, pillage, rape and pillage. That’s all you’re good for. You need to hang on to your ancestral “creations/inventions” that were stolen from other communities because you yourself have nothing left to offer. Your privilege, status and nobility have all gone out the door. Now you’re on the same playing field as everyone else and you feel threatened.

          • Rob

            “I like how you specifically refer to “sub-Saharan” Africans instead of just Africans as a whole.”

            Because we’re discussing the intellectual inferiority of Blacks. Sub-Saharan Africans are Black; the others are not. Couldn’t you figure that out???

            So again… name a single contribution from sub-Saharan Africans to the world.

            The simple fact is, Blacks are the only race incapable of caring for themselves. Whites still have to provide food, medical, financial and engineering aid to every Black nation. They couldn’t survive without White charity. Blacks became an out-of-control invasive species after Whites domesticated them.

          • Rob

            “Whites have been colonizing and trying to get the wealth and resources of other peoples and lands for centuries. … They are most pissed off when somebody is doing fine or better than them and they are excluded.”

            Huh?

            When Whites discovered Blacks just 400 years ago they were still living in the Stone Age. Blacks hadn’t even created a written language. Of course the White colonizers had to do that for them too.

          • Rob

            Are Blacks as smart as Whites?

          • Rob

            Google: National IQ Congo

            ….then: IQ Koko the gorilla

            LOL

            IQ correlates strongly to job performance, increased wealth, increased income, economic growth, livability in a U.S. state, cooperation, life expectancy and infant mortality.

            It is estimated that a minimum IQ of 90 is required just to maintain a technological society.

            The more White a society is the more successful (safe and prosperous) it is.

            The following intelligence scores came from work carried out earlier this decade by Richard Lynn, a British psychologist, and Tatu Vanhanen, a Finnish political scientist, who analysed IQ studies from 113 countries, and from subsequent work by Jelte Wicherts, a Dutch psychologist. Lynn and Vanhanen benchmarked their IQ results so that Britain is 100. America scores 98 on this scale, and the world average is 90. IQ`s are assumed to form a normal probability distribution (“bell curve”) with the standard deviation set at 15.

            National IQ correlates at 0.73 with living standard.

            Each 10 point increase in IQ generally doubles economic growth, assuming the country has a market economy:

                      •   108      Singapore
                      •   106      South Korea
                      •   105      Japan
                      •   105      China
                      •   102      Italy
                      •   101      Iceland
                      •   101      Mongolia
                      •   101      Switzerland
                      •   100      Austria
                      •   100      Luxembourg
                      •   100      Netherlands
                      •   100      Norway
                      •   100      United Kingdom
                      •   99        Belgium
                      •   99        Canada
                      •   99        Estonia
                      •   99        Finland
                      •   99        Germany
                      •   99        New Zealand
                      •   99        Poland
                      •   99        Sweden
                      •   98        Andorra
                      •   98        Australia
                      •   98        Czech Republic
                      •   98        Denmark
                      •   98        France
                      •   98        Hungary
                      •   98        Latvia
                      •   98        Spain
                      •   98        United States
                      •   97        Belarus
                      •   97        Malta
                      •   97        Russia
                      •   97        Ukraine
                      •   96        Moldova
                      •   96        Slovakia
                      •   96        Slovenia
                      •   96        Uruguay
                      •   95        Israel
                      •   95        Portugal
                      •   94        Armenia
                      •   94        Georgia
                      •   94        Kazakhstan
                      •   94        Romania
                      •   94        Vietnam
                      •   93        Argentina
                      •   93        Bulgaria
                      •   92        Greece
                      •   92        Ireland
                      •   92        Malaysia
                      •   91        Brunei
                      •   91        Cambodia
                      •   91        Cyprus
                      •   91        Lithuania
                      •   91        Thailand
                      •   90        Albania
                      •   90        Bosnia
                      •   90        Chile
                      •   90        Croatia
                      •   90        Kyrgyzstan
                      •   90        Turkey
                      •   89        Cook Islands
                      •   89        Costa Rica
                      •   89        Laos
                      •   89        Mauritius
                      •   89        Serbia
                      •   89        Suriname
                      •   88        Ecuador
                      •   88        Mexico
                      •   88        Samoa
                      •   87        Azerbaijan
                      •   87        Bolivia
                      •   87        Brazil
                      •   87        Guyana
                      •   87        Indonesia
                      •   87        Iraq
                      •   87        Myanmar
                      •   87        Tajikistan
                      •   87        Turkmenistan
                      •   87        Uzbekistan
                      •   86        Kuwait
                      •   86        Philippines
                      •   86        Seychelles
                      •   86        Tonga
                      •   85        Cuba
                      •   85        Eritrea
                      •   85        Fiji
                      •   85        Kiribati
                      •   85        Peru
                      •   85        Trinidad and Tobago
                      •   85        Yemen
                      •   84        Afghanistan
                      •   84        Bahamas
                      •   84        Belize
                      •   84        Colombia
                      •   84        Iran
                      •   84        Jordan
                      •   84        Marshall Islands
                      •   84        Micronesia
                      •   84        Morocco
                      •   84        Nigeria
                      •   84        Pakistan
                      •   84        Panama
                      •   84        Paraguay
                      •   84        Saudi Arabia
                      •   84        Solomon Islands
                      •   84        Uganda
                      •   84        United Arab Emirates
                      •   84        Vanuatu
                      •   84        Venezuela
                      •   83        Algeria
                      •   83        Bahrain
                      •   83        Libya
                      •   83        Oman
                      •   83        New Guinea
                      •   83        Syria
                      •   83        Tunisia
                      •   82        Bangladesh
                      •   82        Dominican Republic
                      •   82        India
                      •   82        Lebanon
                      •   82        Madagascar
                      •   82        Zimbabwe
                      •   81        Egypt
                      •   81        Honduras
                      •   81        Maldives
                      •   81        Nicaragua
                      •   80        Barbados
                      •   80        Bhutan
                      •   80        El Salvador
                      •   80        Kenya
                      •   79        Guatemala
                      •   79        Sri Lanka
                      •   79        Zambia
                      •   78        Congo
                      •   78        Nepal
                      •   78        Qatar
                      •   77        South Africa
                      •   76        Cape Verde
                      •   76        Congo
                      •   76        Mauritania
                      •   76        Senegal
                      •   74        Mali
                      •   74        Namibia
                      •   73        Ghana
                      •   72        Tanzania
                      •   71        Central African Republic
                      •   71        Grenada
                      •   71        Jamaica
                      •   71        St Vincent, Grenadines
                      •   71        Sudan
                      •   70        Antigua, Barbuda
                      •   70        Benin
                      •   70        Botswana
                      •   70        Rwanda
                      •   70        Togo
                      •   69        Burundi
                      •   69        Cote d’Ivoire
                      •   69        Ethiopia
                      •   69        Malawi
                      •   69        Niger
                      •   68        Angola
                      •   68        Burkina Faso
                      •   68        Chad
                      •   68        Djibouti
                      •   68        Somalia
                      •   68        Swaziland
                      •   67        Dominica
                      •   67        Guinea
                      •   67        Guinea-Bissau
                      •   67        Haiti
                      •   67        Lesotho
                      •   67        Liberia
                      •   67        Saint Kitts
                      •   67        Sao Tome
                      •   66        Gambia
                      •   64        Cameroon
                      •   64        Gabon
                      •   64        Sierra Leone
                      •   64        Mozambique
                      •   62        Saint Lucia
                      •   59        Equatorial Guinea

          • Rob

            Blacks have small brains

            Would you expect a population of small-brain people to have a higher, lower or equal IQ as compared to a population of large-brain people?

            Compared to Blacks, Whites’ brains:

            • are 7% larger (1438cc versus 1343cc)
            • are 100 grams heavier
            • have deeper fissuration in the frontal and occipital regions
            • have more complex convolutions and larger frontal lobes
            • have more pyramidal neurons
            • have 16% thicker supra-grandular layer
            • react faster on mental chronometry tests
            • have 600 million more neurons (each carries about 600 billion synapses, which each carry one bit of cortical information)

            Genes contribute to about 90% of the individual variation of brain size.

            Asian, White, and Black brains can be reliably differentiated by examining the surface configuration.

            Blacks are the only racial group with no DNA from the large-brained Neanderthals, and also the only race without the derived form of MCPH1 microcephalin called haplogroup D which produces increased brain volume.

            The correlation between brain size and IQ across 25 primate species is 0.77 (where 1.0 indicates that monozygotic twins have no variance in IQ and 0 indicates that their IQs are completely uncorrelated).

            Larger brains contain more neurons and synapses and process information faster. By adulthood, East Asians average 1 cubic inch more cranial capacity than Whites who average 5 cubic inches more than Blacks.

            The average White brain is 1438cc while the average Black brain is 1343cc, or 93% of the average White brain. The heritability of brain size is extremely strong at 0.90 and not one study to date has shown larger brain size for Blacks. The White and Asians brain also has a higher degree of fissuring (higher complexity) in the cerebral cortex of their brains, where abstract and conceptual thought is performed.

            There are also racial differences in brain shape, fissuration, number of pyramidal neurons and supra-grandular layer thickness. The depth of fissuration is related to superior intelligence and the brains of Whites have deeper fissures in the frontal and occipital regions. The supra-grandular layer of Blacks’ brains is 16% smaller than it is for Whites’ brains.

            Based on studies of brain weight at autopsy, endocranial volume of empty skulls, head size measurements by the U.S. military and NASA, and two dozen MRI volumetric studies Blacks’ brain size is 7% smaller than Whites’, and 8% smaller than Asians’. There is a correlation of brain size with IQ of about 0.40 and that these racial differences in brain size are present at birth. Genes contribute to about 90% of the individual variation of brain size.

            In addition to brain size are differences in brain shape, fissuration, number of pyramidal neurons and supra-grandular layer thickness. The depth of fissuration is related to superior intelligence and the brains of Whites have deeper fissures in the frontal and occipital regions. The supra-grandular layer of Blacks’ brains is 16% smaller than it is for Whites’ brains.

            The average human brain contains 86 billion neurons. Whites, on average, have 600 million more neurons than Blacks. Each neuron carries about 600 billion synapses, each of which carries, as a minimum, one bit of cortical information.

            Blacks are the only racial group with no DNA from the large-brained Neanderthals, and also the only race without the derived form of MCPH1 microcephalin called haplogroup D which produces increased brain volume.

            Even before birth, population group differences in average brain size are found from the ninth week of intrauterine life with White fetuses averaging larger brain cases and smaller faces Black fetuses, with the differences becoming more prominent over the course of fetal development.

            Weighing brains at autopsy, Whites averaged heavier brains than Blacks and had more complex convolutions and larger frontal lobes. Subsequent studies have found an average Black–White difference of about 100 g. Studies have found that the more White admixture (judged independently from skin color), the greater the average brain weight in Blacks. In a study of 1,261 American adults, Ho et al. (1980) found that 811 White Americans averaged 1,323 g and 450 Black Americans averaged 1,223 g. Since the Blacks and Whites were similar in body size, differences in body size cannot explain away the differences in brain weight.

            The same three-way pattern of race differences has been found using the simplest culture-free cognitive measures such as reaction time tasks, which 9- to 12-year-old children perform in less than 1 s. Lynn (2006) found that East Asian children from Hong Kong and Japan were faster than European children from Britain and Ireland, who in turn were faster than African children from South Africa. Using similar tasks, this pattern of racial differences was also found in California (Jensen, 1998; Rushton & Jensen, 2005). Within each group, the children with higher IQ scores perform faster those with lower scores.

            Race differences start in the womb. Blacks are born earlier and grow quicker than Whites and Asians. The three-way race pattern occurs in milestones such as sexual maturity, family stability, crime rates, and population growth.

            Black babies mature more quickly than White babies, while Asian babies mature more slowly. Black babies in a sitting position are more able to keep their heads up and backs straight from the start. White babies often need six to eight weeks to do these things. It is unlikely that social factors could produce these differences. A basic law of biology shows that longer infancy is related to greater brain growth.

            Black babies spend the least time in the womb. In America, 51% of Black children have been born by week 39 of pregnancy compared with 33% of White children. In Europe, Black babies of even professional mothers are born earlier than White babies.

            Black children sit, crawl, walk, and put on their own clothes earlier than Whites or Asians. The findings are measured by such tests as Bayley’s Scales of Mental and Motor Development and the Cambridge Neonatal Scales.

            Asian children, on the other hand, mature more slowly than do White children. Asian children often do not walk until 13 months. Walking starts at 12 months for white children and 11 months for Black children.

            ~~~~~~~~~~

            Meta-analysis of associations between human brain volume and intelligence differences

            AUTHORS: Pietschnig, Penke, Wicherts, Zeiler, Voracek

            ABSTRACT: “By means of a systematic review of published studies and unpublished results obtained by personal communications with researchers, we identified 88 studies examining effect sizes of 148 healthy and clinical mixed-sex samples. Our results showed significant positive associations of brain volume and IQ.”

            2015, October

            PMID: 26449760

            ~~~~~~~~

            Brain mass differences between racial groups in the US

            Jensen (1998) summarizes the brain mass findings from the Case-Western Reserve (1980) study (N= 811 W, 450 B). An age matched and height adjusted B-W differences of ~100g (~.78SD) was found, which is commensurate with the findings of Bean (1906), Mall (1909), Pearl (1934), and Vint (1934) as described in Rushton and Ankney (2009). Holloway (2002) found a B-W difference of 63 grams (N = 1,391 W; 615 Black). Similar findings have been found based in imaging studies (see 5). In their study, Isamah, et al. (2010) found that African Americans have 1 SD less total cerebrum volume than European Americans.

            ~~~~~~~~~~~~~~~

            Contrary to most purely environmental theories, racial differences in brain size show up early in life. Data from the U.S. National Collaborative Perinatal Project on 19,000 Black children and 17,000 White children showed that Black children had a smaller head perimeter at birth and, although Black children were born shorter in stature and lighter in weight than White children, by age 7 ‘catch-up growth’ led Black children to be larger in body size than White children. However, Blacks remained smaller in head perimeter (Broman et al., 1987). Further, head perimeter at birth, 1 year, 4 years, and 7 years correlated with IQ scores at age 7 in both Black and White children (r = 0.13 to 0.24).

            ~~~~~~~~~~~~~~

            Brain Size Differences. Studies using magnetic resonance imaging (MRI) find a correlation of brain size with IQ of about 0.40. Larger brains contain more neurons and synapses and process information faster. Race differences in brain size are present at birth. By adulthood, East Asians average 1 cubic inch more cranial capacity than Whites who average 5 cubic inches more than Blacks.

            “Neither the existence nor the size of race differences in IQ are a matter of dispute, only their cause,” write the authors. The Black-White difference has been found consistently from the time of the massive World War I Army testing of 90 years ago to a massive study of over 6 million corporate, military, and higher-education test-takers in 2001.

            “Race differences show up by 3 years of age, even after matching on maternal education and other variables,” said Rushton. “Therefore they cannot be due to poor education since this has not yet begun to exert an effect. That’s why Jensen and I looked at the genetic hypothesis in detail. We examined 10 categories of evidence.”

            1. The Worldwide Pattern of IQ Scores; East Asians average higher on IQ tests than Whites, both in the U. S. and in Asia, even though IQ tests were developed for use in the Euro-American culture. Around the world, the average IQ for East Asians centers around 106; for Whites, about 100; and for Blacks about 85 in the U.S. and 70 in sub-Saharan Africa.

            2. Race Differences are Most Pronounced on Tests that Best Measure the General Intelligence Factor (g); Black-White differences, for example, are larger on the Backward Digit Span test than on the less g loaded Forward Digit Span test.

            3. The Gene-Environment Architecture of IQ is the Same in all Races, and Race Differences are Most Pronounced on More Heritable Abilities; Studies of Black, White, and East Asian twins, for example, show the heritability of IQ is 50% or higher in all races.

            4. Brain Size Differences; Studies using magnetic resonance imaging (MRI) find a correlation of brain size with IQ of about 0.40. Larger brains contain more neurons and synapses and process information faster. Race differences in brain size are present at birth. By adulthood, East Asians average 1 cubic inch more cranial capacity than Whites who average 5 cubic inches more than Blacks.

            5. Trans-Racial Adoption Studies; Race differences in IQ remain following adoption by White middle class parents. East Asians grow to average higher IQs than Whites while Blacks score lower. The Minnesota Trans-Racial Adoption Study followed children to age 17 and found race differences were even greater than at age 7: White children, 106; Mixed-Race children, 99; and Black children, 89.

            6. Racial Admixture Studies; Black children with lighter skin, for example, average higher IQ scores. In South Africa, the IQ of the mixed-race “Colored” population averages 85, intermediate to the African 70 and White 100.

            -June 2005, Psychology, Public Policy and Law, a journal of the American Psychological Association

            ~~~~~~~~~~~~~~

            According to a new study, just published in the University of California Los Angeles (UCLA) newsroom, scientists have definitively found the genes which control brain size and intelligence.

            Dozens of studies have found race differences in brain size, whether measured by MRI, endocranial volume, brain weight at autopsy or external head size (with or without corrections for body size).

            Most were carried out on the three major races of East Asians, Europeans, and Africans. Averaging all the data, the following figures have emerged: Brain size average for East Asians = 1364cm; Whites = 1347cm; and Blacks = 1267cm.

            The overall mean for East Asians was 17cm more than for Whites and 97cm more than for Blacks.

            Since every cubic centimeter of brain tissue contains millions of brain cells and billions of synapses, the race differences in brain size help to explain the race differences in IQ.

            The latest overview, billed as the “world’s largest brain study to date,” saw a team of more than 200 scientists from 100 institutions worldwide collaborate to map the human genes that boost or sabotage the brain’s resistance to a variety of mental illnesses and Alzheimer’s disease.

            Additionally, the study (also published in the journal Nature Genetics), found new genes which control “differences in brain size and intelligence.”

            “We searched for two things in this study,” said senior author Paul Thompson, professor of neurology at the David Geffen School of Medicine at UCLA and a member of the UCLA Laboratory of Neuro Imaging.

            “We hunted for genes that increase your risk for a single disease that your children can inherit. We also looked for factors that cause tissue atrophy and reduce brain size, which is a biological marker for disorders like schizophrenia, bipolar disorder, depression, Alzheimer’s disease and dementia.”

            Three years ago, Thompson’s lab partnered with geneticists Nick Martin and Margaret Wright at the Queensland Institute for Medical Research in Brisbane, Australia, and with geneticist Barbara Franke of Radboud University Nijmegen Medical Centre in the Netherlands.

            The four investigators recruited brain-imaging labs around the world to pool their brain scans and genomic data, and Project ENIGMA (Enhancing Neuro Imaging Genetics through Meta-Analysis) was born.

            “Our individual centers couldn’t review enough brain scans to obtain definitive results,” said Thompson, who is also a professor of psychiatry at the Semel Institute for Neuroscience and Human Behavior at UCLA.

            “By sharing our data with Project ENIGMA, we created a sample large enough to reveal clear patterns in genetic variation and show how these changes physically alter the brain.”

            ~~~~~~~~~~~~~~~

            Recent reviews (by Nisbett et al. (2012b) and Mackintosh (2011)) confirm current data does show an average difference in brain size and head-circumference between American Blacks and Whites.

            Brain size is found to have a correlation of about .35 with intelligence and cites studies showing that genes may account for as much as 90% of individual variation in brain size, concluding that race differences in average brain size could be an important argument for genetic contribution to racial IQ gaps.

            – Considerations Relating to the Study of Group Differences in Intelligence, Earl Hunt1 and Jerry Carlson, The University of Washington
            – American Psychologist, Vol 67(6), Sep 2012, 503-504

            On the outside, there’s not a lot of difference between Black heads and White ones. There is a slight difference, however, with Whites having the larger heads. But the big difference is in the size of the brain. Blacks have thicker skulls, which means that a higher percentage of their head is bone instead of brain.

            Blacks are the only race without the derived form of MCPH1 microcephalin called haplogroup D which appeared about 37,000 years ago and is associated with increased brain volume.

            Empirical data obtained from brain weight at autopsy, endocranial volume of empty skulls, head size measurements by the U.S. military and NASA, and two dozen MRI volumetric studies have shown that brain volumes average 1427 cubic centimeters for Whites, but only 1361 cubic centimeters for Blacks.

            In weight measurements, the brains of African Blacks were found to weigh an average of 1157 grams, whereas those of pure Whites weighed an average of 1323 grams. The brains of US-resident Blacks, who have a bit of White mixture in their genetic makeup, average 1223 grams in weight.

            That 100-gram weight difference, between White Americans and US-resident Blacks, corresponds to an approximate 600 million neuron advantage for Whites. In 600 million neurons, there are about 600 billion synapses, each of which carries, as a minimum, one bit of cortical information.

            Also, Whites have a larger genus to splenium ratio (front to back part of corpus callosum), which indicates that Whites probably have more activity in the frontal lobes which are thought to be the seat of intelligence. One study found that White cerebrums exhibited 14% more sulsification, or fissuring, as compared with those of Blacks. So, not only are White brains larger, they are also significantly more complex.

            Blacks also have considerably smaller frontal lobes. Frontal lobes are responsible for planning complex cognitive behavior, personality expression, decision making and moderating social behavior.

            This is a genetic trait because even malnourished Asians from poor countries have a larger brain on average than well fed blacks from western countries.

            Sources:

            Willerman et al. (1991) Using MRI obtained r’s ranging from .26 to .56 between IQ and the size of specific brain structures and an overall r of .38 between full-scale IQ and gray matter volume when body size is controlled for. Replications by Raz et al. (1993) and Wickett, Vernon and Lee (1994) found correlations between IQ and brain size of .41 and .47-49. Egan et al. (1994) found an r of .32 between IQ and brain size in a sample whose SD for IQ was 9.3.

            Beals, K. L., Smith, C. L., & Dodd, S. M. (1984). Brain size, cranial morphology, climate, and time machines. Current Anthropology 25, 301–330.

            Jensen, A. R. (1998). The g Factor. Westport, CT: Praeger.

            Rushton, J. P. & Ankney, C. D. (1996). Brain size and cognitive ability: Correlations with age, sex, social class, and race. Psychonomic Bulletin and Review, 3, 21-36.

            Ho, K. C., Roessmann, U., Straumfjord, J. V., & Monroe, G. (1980). Analysis of brain weight: I and II. Archives of Pathology and Laboratory Medicine 104, 635–645.

            Johnson F. W. & Jensen (1994). Race and sex differences in head size and IQ. Intelligence 18: 309–33

            Rushton JP. (1997). Cranial size and IQ in Asian Americans from birth to age seven. Intelligence 25: 7–20.

            Rushton JP (1991). Mongoloid-Caucasoid differences in brain size from military samples [and NASA]. Intelligence 15: 351–9.

  • Let’s 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 affects 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 the 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 these changes in the 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.

    It’s also worth noting that the Flynn Effect is, mostly just better nutrition. Rushton also stated that the Flynn Effect wasn’t on the g factor.

    • Did you read this article prior to leaving this comment?

    • Saying blacks have very similar environment isn’t going to cut with equality crowd. You should show that for better environment blacks get similar IQs as whites, like poor whites scoring better or same as rich blacks and blacks with college educated parents getting same NAEP scores as white kids with high-school dropouts parents.

      http://www.unz.com/isteve/applying-occams-razor-vs-asserting-occams-racist/

      • Rob

        Black-White SAT Score Gap by Year:

               Year              White             Black               Gap
               1986              1038               839                 199
               1990              1031               849                 185
               1996              1052               857                 195
               2000              1060               859                 201
               2005              1061               863                 197
               2010              1063               855                 208

        Source: U.S. Dept. of Education, Digest of Education Statistics, 2012

        Note that there is no closing of the large and persistent so-called “achievement gap”.

        In the 20 year period from 1994-2014 the Black-White difference increased on both the verbal and math SATs. On the reading test, it rose from .91 to .96 standard deviations. On the math test, it rose from .95 to 1.03 standard deviations.

        In 2015 only 16% of Blacks scored 1550 or higher, the threshold the College Board calls the “college and career readiness” level.

        This racial achievement gap is so significant that colleges give a “race bonus” of 230 points to Blacks and penalize Asians by 50 points to try to keep it even.

        Frey and Detterman (2003) analyzed the correlation of SAT scores with intelligence test scores. They found SAT scores to be highly correlated with general mental ability, or g (r=.82 in their sample).

        Abstract

        This research established the relationship between SAT and g, as well as the appropriateness of the SAT as a measure of g, and examined the SAT as a premorbid measure of intelligence. In Study 1, we used the National Longitudinal Survey of Youth 1979. Measures of g were extracted from the Armed Services Vocational Aptitude Battery and correlated with SAT scores of 917 participants. The resulting correlation was.82 (.86 corrected for nonlinearity). Study 2 investigated the correlation between revised and recentered SAT scores and scores on the Raven’s Advanced Progressive Matrices among 104 undergraduates. The resulting correlation was.483 (.72 corrected for restricted range). These studies indicate that the SAT is mainly a test of g. We provide equations for converting SAT scores to estimated IQs; such conversion could be useful for estimating premorbid IQ or conducting individual difference research with college students.

        Frey MC, Detterman DK.

        PMID: 15147489 [PubMed – indexed for MEDLINE]

        ~~~~~

        New York Times, 2003:

        The SAT captures more than a narrow range of skills, important only in the first year or two of college. Large-scale meta-analyses by researchers at the University of Minnesota have found that SAT performance is as good of a predictor of overall college grade point average as it is of freshman grade point average, and Vanderbilt researchers David Lubinski and Camilla Benbow have documented that the SAT predicts life outcomes well beyond the college years, including income and occupational achievements.

        Furthermore, the SAT is largely a measure of general intelligence. Scores on the SAT correlate very highly with scores on standardized tests of intelligence, and like IQ scores, are stable across time and not easily increased through training, coaching or practice. SAT preparation courses appear to work, but the gains are small — on average, no more than about 20 points per section.

        ~~~~~~~

        ACT Scores by Race:

               Year              White             Black               Asian
               2009              22.2               16.9                 23.2
               2010              22.3               16.9                 23.4
               2011              22.4               17.0                 23.6
               2012              22.4               17.0                 23.6
               2013              22.2               16.9                 23.5
              
        Source: ACT, Inc.

        ~~~~~

        Percent by Race Reaching the SAT College and Career Readiness Benchmark:

                         15% = Black
                         24% = Non-White Hispanic
                         35% = Native American
                         53% = White
                         56% = Asian               

        Source: The College Board, 2014

        ~~~~~

        Black-White SAT Score Gap by Income:

               Year              White              Black               Gap
               -$20k              978                 798                 180
               $40k               995                 836                 159
               $60k               1017               864                 153
               $80k               1032               889                 143
               $100k             1052               908                 144
               $120k             1066               922                 144
               $140k             1073               926                 147
               $160k             1087               942                 145
               $200k             1091               943                 148
               +200k             1130               981                 149

        Source: The College Board, 2008

        So, Blacks from families earning more than $200k only scored 3 points higher than Whites from families earning less than $20k.

        We will continue with racial preferences in college admissions and job hiring. We will continue to blame black underachievement on racism. We will continue to dumb down education and occupational standards in order to achieve higher proportions of Blacks.

        Differences in intelligence between income groups are not larger than intelligence differences between racial groups in the US, nor do differences in income or wealth account for the racial differences. Whites from households in the lowest income bracket have higher IQ scores than blacks from households in the highest income bracket.

        Black students coming from families earning over $70,000 USD are doing worse on their SATs on average than White students from families in the lowest income group.

        One of the largest modern sociology studies of American students found that ethnicity was the single most important predictor of academic achievement:

        “Beyond the Classroom,” by Laurence Steinberg, B. Bradford Brown and Sanford M. Dornbusch, concludes “Of all the demographic factors we studied in relation to school performance, ethnicity was the most important. In terms of school achievement, it is more advantageous to be Asian than to be wealthy, or to have non-divorced parents, or to have a mother who is able to stay at home full time.”

        A number of experiments are able to test all of these environmental theories. Transracial adoption experiments control for all the shared aspects of the environment that differ between Whites and Blacks (parenting, income, nutrition, neighborhood), while structural equation models test for possible uncommon factors between Whites and Blacks that could be acting on IQ (which would include things like racism). These experiments do not lend support to any existing or plausible environmental theories for the remaining lower intelligence scores of people of African descent in Western societies. The Minnesota Transracial Adoption Study found that, by adulthood, the difference in IQ scores between adopted black and adopted White children raised side by side in the same high income households in mostly homogeneous Northern US upper class neighborhoods was 18 IQ points.

        ~~~~~~~

        The large and persistent so-called “achievement gap” has remain steady since it was first observed.

        Evidence of the racial achievement gap has been manifested through standardized test scores, high school dropout rates, high school completion rates, college acceptance and retention rates, and longitudinal trends.

        It has been found to exist before students enter kindergarten for their first year of schooling. At the start of kindergarten, Black students have math and reading scores substantially lower than those of White students. In a study published in 2009, Reardon and Galindo (2009) specifically examine test scores by race. The data comes from the ECLS-K, sponsored by the National Center for Education Statistics. The ECLS-K contains data on a nationally representative sample of approximately 21,400 students from the kindergarten class of 1998–1999. Students in the sample were assessed in reading and mathematics skills six times from 1998 to 2004. The content areas of the tests are based on the National Assessment of Educational Progress (NAEP) fourth-grade content areas, adapted to be age appropriate at each grade level. The assessments were scored using a three-parameter Item Response Theory (IRT) model. Reardon and Galindo found that average Black students begin kindergarten with math scores three quarters of a standard deviation lower than those of White students. Six years later the gap widens by about a third.

        The racial group differences across admissions tests, such as the SAT, ACT, GRE, GMAT, MCAT, LSAT, Advanced Placement Program examinations and other measures of educational achievement, have been consistent. Since the 1960s, the population of students taking these assessments has become increasingly diverse. Consequently, the examination of ethnic score differences have been more rigorous. Specifically, the largest gaps exist between White and Black students. On average, Blacks score about .82 to 1.18 standard deviations lower than White students in composite test scores.

        The National Assessment of Educational Progress reports the national Black-White gap in math and reading assessments, measured at the 4th and 8th grade level. The trends show the achievement gaps staying the same.

        ~~~~~~~

        Racial Scoring Gap on Standardized Graduate Tests

        — Black Student Score Results on the Medical College Admission Test

        In 2005 the mean combined score for Black students who took the Medical College Admission Test was 21.2. (Each of the three sections of the MCAT test is scored on a scale of 1 to 15.) For Whites, the mean score on the combined three portions of the MCAT test was 28.5. Therefore, the White score was about 18 percent higher than the mean score for Blacks.

        — The Racial Scoring Gap on the Test for Admission to Business School

        The mean Black score on the GMAT was 425. (The test is scored on the familiar 200 to 800 scale used for each section of the SAT test.) For Whites, the mean GMAT score was 532. This is 107 points or 18 percent higher than the mean score for Blacks.

        The average GMAT score for admitted students at the nation’s leading business schools is over 700. Perhaps only 1 or 2 percent of all Black GMAT test takers score at this level. Therefore, without continuing affirmative action admissions programs at Harvard, Penn, Stanford, Northwestern, MIT, and other top MBA programs, the nation’s leading business schools will have very few Black students.

        The latest JBHE survey shows that Blacks make up about 5 percent of the students at the nation’s leading business schools. If affirmative action admissions programs were to be discontinued, Black enrollments at these schools might drop by 75 percent.

        — Very Few Blacks Score at the Highest Levels of the Law School Admission Test

        In 1998 the mean score of White students taking the Law School Admission Test (LSAT) was 151.96. (The LSAT is graded on a scoring scale of 120 to 180.) The mean score for Black students taking the test that year was 141.80, about 17 percent lower than the mean score of Whites.

        The latest data shows a slight improvement for both Blacks and Whites, but there was no progress in closing the racial scoring gap. In 2004 the mean score for Whites on the LSAT was 152.47. For Blacks, the mean score was 142.43. The 10 point, or 17 percent, scoring gap has remained constant throughout the period with only very minor fluctuations.

        Students seeking admission to the nation’s highest-ranked law schools such as Yale, Harvard, and Stanford have a mean LSAT score of about 170. Data obtained by JBHE from the Law School Admission Council shows that very few Blacks nationwide score at this level.

        In 2004, 10,370 Blacks took the LSAT examination. Only 29 Blacks, or 0.3 percent of all LSAT test takers, scored 170 or above. In contrast, more than 1,900 White test takers scored 170 or above on the LSAT. They made up 3.1 percent of all White test takers. Thus Whites were more than 10 times as likely as Blacks to score 170 or above on the LSAT. There were 66 times as many Whites as Blacks who scored 170 or above on the test.

        Even if we drop the scoring level to 165, a level equal to the mean score of students enrolling at law schools ranked in the top 10 nationwide but not at the very top, we still find very few Blacks. There were 108 Blacks scoring 165 or better on the LSAT in 2004. They made up 1 percent of all Black test takers. For Whites, there were 6,689 test takers who scored 165 or above. They made up 10.6 percent of all White students who took the LSAT examination.

        The nation’s top law schools could fill their classes exclusively with students who scored 165 or above on the LSAT. But if they were to do so, these law schools would have almost no Black students.

        — The Racial Scoring Gap on the Graduate Record Examination

        The vast majority of Black graduate students do not attend professional schools of law, business, or medicine. Most Black students are enrolled in graduate programs in other academic disciplines including education, natural sciences, mathematics, foreign languages, the humanities, the arts, history, psychology, and the social sciences. For these students the important test is the Graduate Record Examination (GRE).

        This test begins with two analytical writing sections, one where the student is given a choice of topics. The analytical writing section is scored on a scale of 0 to 6. Then there is a 30-minute verbal reasoning test and a 45-minute quantitative section. The test is given on a computer terminal and the test is adaptive, meaning that the test questions are selected based on correct or incorrect responses to previous questions. These two sections are scored on the familiar 200 to 800 scale used for the SAT test.

        Each year about 300,000 college students seeking admission to graduate programs in fields such as education, the humanities, the natural sciences, and the social sciences sit for the GRE. In 2003, the latest year for which there is complete data available, 27,267 Blacks took the GRE test. Therefore, Blacks made up 8.8 percent of all students who took the GRE.

        In 2003 the mean score for Blacks on the combined verbal and quantitative sections of the GRE was 821. For Whites, the mean combined score was 1062. Thus the mean White score was 241 points, or 20 percent, higher than the mean score for Blacks. This racial scoring gap is even wider than the persistent and growing gap on the SAT test.

        In 2003 the mean Black score on the analytical writing section was 3.7 on a scale of 0 to 6. For Whites, the mean score was 4.5, a difference of about 13 percent. There is no way to compare the trend in the gap on this portion of the GRE because the 0 to 6 scale was recently instituted. Previously the analytical section of the test was scored on the 200 to 800 scale.

        The GRE scoring gap between Blacks and Whites varies to a large degree depending on the field of proposed study in graduate school. Black students planning to study in the field of engineering scored on average 187 points below whites who plan to pursue a graduate degree in engineering. In the physical sciences, Black students on average scored 247 points below Whites.

    • Rob

      “It’s also worth noting that the Flynn Effect is, mostly just better nutrition.”

      Genetics limits an individuals’ upper limit to IQ, and environment determines how much of that innate genetic potential will be reached. No amount of nurturing can make one exceed innate genetic potential.

      The simple fact is, Blacks have small, primitive brains. That can never be overcome. They are genetically inferior.

  • Chaim Goldberg

    I’m confused by this part

    “For instance, “general processing speed” may be part of general
    intelligence and may help people add numbers. However, people who can
    generally think equally quickly may still differ in how fast they can
    add.”

    People who think quickly differ on how fast they add? How? If they process at the same speed then the should add at the same speed.

    • It’s a poorly worded explanation of how intelligence subtests work.

    • “General processing speed” would refer to how quickly people think generally. People do not do all mental tasks with equal speed though, and for some people those neurological factors which contribute specifically to addition may be more efficient than they are for other people who generally preform mental tasks with the same speed as them.

    • Rob

      Digit Span Tests

      In digit span tests, the respondents are asked to repeat a string of digits. There are two variants of the test, forward digit span (FDS) and backward digit span (BDS). In FDS, the digits are repeated in the order of their presentation, while in BDS they must be repeated in the reverse order. The largest number of digits that a person can repeat without error is his or her forward or backward digit span.

      That the Black-White gap on FDS is substantially smaller than on BDS is a robust finding confirmed in new analysis. This poses a challenge to the argument that racial differences in exposure to the kinds of information that are needed in cognitive tests cause the Black-White test score gap. The informational demands of the digit span tests are minimal, as only the knowledge of numbers from 1 to 9 is required. FDS is a simple memory test assessing the ability to store information and immediately recall it. The informational demands of BDS are the same as those of FDS, but the requirement that the digits be repeated in the reverse order means that it is not simply a memory test, but one that also requires mental transformation or manipulation of the information presented.

      Black-White Digit Span:

      Forward Digit Span Difference

      Age 7              Age 9               Age 11
        0.01                 0.04                   0.16

      Backward Digit Span Difference

      Age 7              Age 9               Age 11
       0.43                 0.31                  0.36

      It was predicted that forward digit span (FDS) should correlate less with IQ than backward digit span (BDS), and age and race should interact with FDS-BDS, with the FDS-BDS difference decreasing as a junction of age and a greater White-Black difference in BDS than in FDS. The predictions were substantiated at a high level of significance in large representative samples of 669 White and 622 Black 5-12 yr olds who were given the revised WISC. Socioeconomic differences accounted for less of the predicted effects than race. (25 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)

      The “backward digit span” test is not reinforced by any socialization and is not a taught skill for either race; Whites score better at recalling digits presented in order, but recalling the digits in reverse order requires mental transformation and is a good predictor of IQ. The race gap for the backward digit span is twice as great as for the forward test.

      In sum, race differences are most pronounced on tests that best measure the General Intelligence Factor (g). Black-White differences, for example, are larger on the Backward Digit Span test than on the less g loaded Forward Digit Span test.

      ~~~~~~~~~

      Mental Chronometry or Reaction Time Tests

      Mental chronometry measures the elapsed time between the presentation of a sensory stimulus and the subsequent behavioral response by the participant.

      The races differ on average cognitive speed. Even the speed with which one neuron in the brain fires correlates with IQ.

      Reaction time is one of the simplest culture-free cognitive measures. Most reaction time tasks are so easy that children can perform them in less than one second. But even on these very simple tests, children with higher IQ scores perform faster than do children with lower scores, perhaps because reaction time measures the neurophysiological efficiency of the brain’s capacity to process information accurately—the same ability measured by intelligence tests (Deary, 2000; Jensen, 1998b). Children are not trained to perform well on reaction time tasks (as they are on certain paper-and-pencil tests), so the advantage of those with higher IQ scores on these tasks cannot arise from practice, familiarity, education, or training.

      For three reaction time tasks (the simple, choice, and odd-man-out tasks), individuals with higher IQ scores average faster and less variable reaction times. For any one task, the correlation between reaction time and IQ normally lies between .20 and .40. A review of several studies concluded that the six measures combined (i.e., the average time and the variability for the three reaction time tasks) produce a multiple correlation of .67 (Deary, 2000). This is about the same magnitude as the correlation between two conventional intelligence tests of reasoning ability and vocabulary.

      Lynn and his colleagues carried out a series of reaction time studies on over 1,000 nine-year-old East Asian children in Japan and Hong Kong, White children in Britain and Ireland, and Black children in South Africa (summarized by Lynn & Vanhannen, 2002, pp. 66–67). The Progressive Matrices were given as a nonverbal test of intelligence, along with the simple, choice, and odd-man-out tasks. Reaction times and variabilities were measured by computer and hence were not subject to any human error in recording.

      Measured IQ scores of the reaction time test participants:
      Hong Kong: 113
      Japan: 110
      Briton: 100
      Ireland: 89
      South Africa: 67

      Odd-man Out Reaction Time Test (milliseconds):
      Hong Kong: 787
      Japan: 818
      Briton: 898
      Ireland: 902
      South Africa: 924