Medical What Are the Molecular Correlates of Intelligence and IQ?

[phusicist]

I realize that IQ has been discussed on this forum to the nth but I also noticed that most everyone in those threads simply dismissed IQ as some triviality. But neuroscience (Not to be confused with Cognitive science, which is Behavioural Psychology of the mind) and other fields for that matter have made some huge strides ever since Dr. Binet first created his test. The science of intelligence is now a molecular science. IQ has physiological correlates. Here are a few interesting studies for starters:

http://www.gnxp.com/MT2/archives/002366.html
http://www.gnxp.com/MT2/archives/003370.html

 

[selfAdjoint]

Yup. It's good to see you referencing ww.gnxp.com, I check it every day. The usual way of dismissing what it discusses and links to is to cry "racist" and cite something on the sidebar of sombody on the sidebar of gnxp (e.g. Steve Sailer is on the sidebar at gnxp, and VDare is on his sidebar, and although the posters at VDare insist they are not racist, some of their posts and comments can be presented to sound that way.)

But of course that is not a scientific approach even though some scientists use it. It's just a ploy (original definition of ploy: a move in the metagame) to avoid looking at the correct experiments and genuine scholarly discussions they have there.

 

[Pengwuino]

Is there an actual scientific connection between race and IQ? If IQ is something on the molecular level, it sounds reasonable there would be at least a small connection.

 

[Moonbear]

Yup. It's good to see you referencing ww.gnxp.com, I check it every day. The usual way of dismissing what it discusses and links to is to cry "racist" and cite something on the sidebar of sombody on the sidebar of gnxp (e.g. Steve Sailer is on the sidebar at gnxp, and VDare is on his sidebar, and although the posters at VDare insist they are not racist, some of their posts and comments can be presented to sound that way.)

But of course that is not a scientific approach even though some scientists use it. It's just a ploy (original definition of ploy: a move in the metagame) to avoid looking at the correct experiments and genuine scholarly discussions they have there.

Usually the discussions that have started here have been dismissed because they are presented with a racist slant. It's not that there isn't a biological basis to learning, but the way people have attempted to twist the findings to mean something they do not in order to oppress members of certain racial or ethnic groups. It is one thing to identify differences and another to assume those differences imply superiority or inferiority, which has too often happened in discussions on IQ in this forum.

There are also a lot of topics here that have dismissed IQ tests, mainly because they start out with either some internet test that does not accurately measure IQ, or because they are again drawing inferences and significance from those tests beyond what they are intended to measure. There is a difference between using a tool such as an IQ test to survey populations and look for correlations between abilities in performing certain types of tasks with other biological factors, and claiming the results of such a survey serve any actual predictive purpose or that the correlations imply causation.

If the unscientific assumption that correlation means causation can be left out of the discussion, as well as any assumptions that something being different necessarily makes it better or worse than something else, then it's possible to have a reasonable scientific discussion of the topic.

 

[Agent C.I]

to pengwuino

Race is a genetic factor, not a molecular one.

In genetics the color of your skin and eyes and height and the shape of your body does not effect your intelligence...

So predominantly the race you’re identified as dew to these genetic properties does not effect your i.q in any such way.

However there is in fact a gene which specifically involves the correlation of natural intelligence.

 

[phusicist]

Race is a genetic factor, not a molecular one,

In genetics the color of your skin and eyes and height and the shape of your body does not effect your intelligence...

So predominantly the race you’re identified as dew to these genetic properties does not effect your i.q in any such way.

However there is in fact a gene which specifically involves the correlation of natural intelligence.

Genetics IS a molecular science. Our differences are more than skin deep.

"researchers can use some genetic information to group individuals into clusters with medical relevance"

"scientists have collected data about the genetic constitution of populations around the world in an effort to probe the link between ancestry and patterns of disease. "

“Ultimately, all of genetics boils down to measuring the genetic variation in some population of people and comparing it to their characteristics and looking for correlations. That’s all genetics ever is.” And, adds Altshuler, the HapMap “is simply a tool to study genetic variation at unprecedented levels of accuracy and detail.”

"...differences between Asian brains and European brains...brains in Asian populations tend to be spherical...European brains tend to be more elongated...this must be some aspect of evolution and how the genetics of the brain determine its shape and structure..."

UCLA Brain Mapping Center

"A new study conducted by racial intelligence difference researchers J. Philippe Rushton of the University of Western Ontario and Arthur R. Jensen of the University of California, Berkeley, argues that average differences in intelligence between blacks, whites and East Asians can be attributed to race and genetics. Their research findings were published as the lead essay in the current issue of Psychology, Public Policy and Law—a journal of the American Psychological Association—which also includes 4 responses (1 positive, 3 critical) as well a reply from the authors. Like Dr. Armand Leroi’s Op-Ed in The New York Times, the Rushton-Jensen study raises questions of critical importance in the policy arena that also call for informed debate among scholars, policy makers, journalists and the public at large."

I don't see what the problem is. Different populations differ, OBVIOUSLY. In height, in skin tone, in hormones, in bone structure, in IQ etc...

If you're interested in learning more about race, check these links out:

http://psom.blogspot.com/2006/01/race-fact-or-fiction.html
http://psom.blogspot.com/2006/02/race-reprised-and-difficulties-of.html

 

[phusicist]

Pengwuino, check out the links I provided. You'd first have to define "race". When biologists use it, they usually mean geographic origin. Geographic location is the best single explanation for human genetic variation. So their categorization, if at all, would be a far cry from the standard broad groupings of race.

 

[Monique]

I don't see what the problem is. Different populations differ, OBVIOUSLY. In height, in skin tone, in hormones, in bone structure, in IQ etc...

But how much is accounted by genes and how much by environment. Take height for instance, you must know that a chinese child born in the US becomes larger than its parents. The children of that person will still get larger until a plateau is reached.

 

[Mk]

As for environment, isn't it just what you eat? What else would change your height?

 

[phusicist]

But how much is accounted by genes and how much by environment. Take height for instance, you must know that a chinese child born in the US becomes larger than its parents. The children of that person will still get larger until a plateau is reached.

Twin studies are ideal for empirically testing this kind of stuff, because comparing the correlation of IQ between identical twins, which share environment and genes, with fraternal twins, which share environment but not genes, allows the degree of heritability to be accurately determined.

I think that heritability is correlated less with IQ only in situations where environmental conditions are a variable. Specifically the low socio-economic end of the population, where malnutrition and even pollution appear to be detrimental for cognitive development, and even height.

 

[selfAdjoint]

Twin studies are ideal for empirically testing this kind of stuff, because comparing the correlation of IQ between identical twins, which share environment and genes, with fraternal twins, which share environment but not genes, allows the degree of heritability to be accurately determined.

I think that heritability is correlated less with IQ only in situations where environmental conditions are a variable. Specifically the low socio-economic end of the population, where malnutrition and even pollution appear to be detrimental for cognitive development, and even height.

For example see http://www.psych.umn.edu/psylabs/mtfs/special.htm". In describing the most famous US twin study, it also discusses some of the methodology.

 

[Monique]

Twin studies are ideal for empirically testing this kind of stuff, because comparing the correlation of IQ between identical twins, which share environment and genes, with fraternal twins, which share environment but not genes, allows the degree of heritability to be accurately determined.

I don't think the quantity and the quality of identical twins ever has been good enough to make accurate measurements of the heritability of IQ. Sociological twin studies in the past have been surrounded by controversy. An example of the lack of quality of twins raised apart: very few twins have been separated shortly after birth and many reunited years before the onset of any studies, also many were raised within branches of the same family. There are a few examples of twins that were monitored from birth and were kept in the dark about each other's existence (the triplet studies by Neubauer is an exception I know of, but I don't think he ever published his results).

I think that heritability is correlated less with IQ only in situations where environmental conditions are a variable. Specifically the low socio-economic end of the population, where malnutrition and even pollution appear to be detrimental for cognitive development, and even height.

Yes, studies have indicated that. It's easier to lower someone's IQ than to raise it. Environmental extremes will have impact, although I think the general conclusion of studies has been that it does not really matter what class a separated twin grows up in.

Maybe you can recommend an article that you think shows the heritability of IQ in MZ twins so that we can review the data.

 

[selfAdjoint]

I don't think the quantity and the quality of identical twins ever has been good enough to make accurate measurements of the heritability of IQ. Sociological twin studies in the past have been surrounded by controversy. An example of the lack of quality of twins raised apart: very few twins have been separated shortly after birth and many reunited years before the onset of any studies, also many were raised within branches of the same family. There are a few examples of twins that were monitored from birth and were kept in the dark about each other's existence (the triplet studies by Neubauer is an exception I know of, but I don't think he ever published his results).

Would you state or link to any evidence that for example the famous Minnesota twin studies have been influenced by these considerations? There have been, I suppose, thousands of twin studies since Galton. Are you tarring all of them with the same brush?

 

[Phenelzine]

http://www.sciencedaily.com/releases/2010/01/100121155220.htm"
Controversial Study of African IQ Levels Is 'Deeply Flawed'

ScienceDaily (Jan. 21, 2010) - The controversial study on African IQ levels conducted by psychologist Richard Lynn is deeply flawed. This conclusion is the outcome of studies by Jelte Wicherts, Conor Dolan, Denny Borsboom and Han van der Maas of the University of Amsterdam (UvA) and Jerry Carlson of the University of California (Riverside).

Their findings are set to be published in Intelligence, Personality and Individual Differences, and Learning and Individual Differences.

In an oft-quoted literature study conducted in 2006, Lynn concluded that black Africans have an average IQ of less than 70 (compared to an average western IQ of 100). Lynn suggested that these low IQs are indicative of a low intelligence level, claiming this offered an explanation for the low level of economic development in sub-Saharan countries.

Lynn's study is well known among psychologists, and has been referenced by academics such as Nobel laureate James Watson, and the authors of the controversial book The Bell Curve -- Intelligence and Class Structure in America (Richard Herrnstein and Charles Murray: Freepress, 1994).

African IQ scores prove flawed

Wicherts and his colleagues examined over 100 published studies, concluding that there is no evidence to back up Lynn's claims. Amongst other flaws, Lynn used selective data by systematically ignoring Africans with high IQ scores. The researchers also claim that African IQ test scores cannot be interpreted in terms of lower intelligence levels, as these scores have different psychometric characteristics than western IQ test scores. Until now, the incomparability of Western and African IQ scores had never been systematically proven.

The scientists point out that the average African IQ is currently comparable to the average level in the Netherlands around 1950. However, IQ scores in Western countries have risen sharply over the course of the 20th century. In view of this trend, Wicherts and his colleagues claim there are no reasonable grounds to conclude that sub-Saharan countries are poor due to the lower IQ scores of their populations. As it turns out, the average IQ of African adults is seeing a similar rising trend, which is expected to continue if living conditions in Africa improve in future.

 

[Phenelzine]

Personality and Individual Differences
Volume 48, Issue 2, January 2010, Pages 91-96
doi:10.1016/j.paid.2009.05.028
Copyright c 2009 Elsevier Ltd All rights reserved.

Review

Why national IQs do not support evolutionary theories of intelligence

Jelte M. Wicherts, Denny Borsbooma and Conor V. Dolana

aDepartment of Psychology, University of Amsterdam, Roetersstraat 15, 1018 WB Amsterdam, The Netherlands

Received 16 February 2009; revised 19 May 2009; accepted 26 May 2009. Available online 24 June 2009.

Abstract

Kanazawa (2008), Templer (2008), and Templer and Arikawa (2006) claimed to have found empirical support for evolutionary theories of race differences in intelligence by correlating estimates of national IQ with indicators of reproductive strategies, temperature, and geographic distance from Africa. In this paper we criticize these studies on methodological, climatic, and historical grounds. We show that these studies assume that the Flynn Effect is either nonexistent or invariant with respect to different regions of the world, that there have been no migrations and climatic changes over the course of evolution, and that there have been no trends over the last century in indicators of reproductive strategies (e.g., declines in fertility and infant mortality). In addition, we show that national IQs are strongly confounded with the current developmental status of countries. National IQs correlate with all the variables that have been suggested to have caused the Flynn Effect in the developed world.

Keywords: Evolutionary psychology; Flynn Effect; Race differences

Find entire study here: http://wicherts.socsci.uva.nl/wicherts2010.pdf"

 

[Phenelzine]

Personality and Individual Differences
Volume 48, Issue 2, January 2010, Pages 104-106
doi:10.1016/j.paid.2009.08.020
Copyright c 2009 Elsevier Ltd All rights reserved.

Short Communication

Evolution, brain size, and the national IQ of peoples around 3000 years B.C

Jelte M. Wicherts a, Denny Borsboom a and Conor V. Dolan a

aUniversity of Amsterdam, Department of Psychology, Amsterdam, The Netherlands

Received 22 August 2009; accepted 26 August 2009. Available online 18 September 2009.

Abstract

In this rejoinder, we respond to comments by Lynn, Rushton, and Templer on our previous paper in which we criticized the use of national IQs in studies of evolutionary theories of race differences in intelligence. We reiterate that because of the Flynn Effect and psychometric issues, national IQs cannot be taken to reflect populations' levels of g as fixed since the last ice age. We argue that the socio-cultural achievements of peoples of Mesopotamia and Egypt in 3000 B.C. stand in stark contrast to the current low level of national IQ of peoples of Iraq and Egypt and that these ancient achievements appear to contradict evolutionary accounts of differences in national IQ. We argue that race differences in brain size, even if these were entirely of genetic origin, leave unexplained 91-95% of the black-white IQ gap. We highlight additional problems with hypotheses raised by Rushton and Templer. National IQs cannot be viewed solely in evolutionary terms but should be considered in light of global differences in socio-economic development, the causes of which are unknown.

Keywords: Evolutionary psychology; Flynn Effect; Race differences; Brain size

Find entire study here: http://wicherts.socsci.uva.nl/wichertsPAIDrejoinder.pdf"

 

[Phenelzine]

Intelligence
Volume 38, Issue 1, January-February 2010, Pages 1-20
doi:10.1016/j.intell.2009.05.002
Copyright c 2009 Elsevier Inc. All rights reserved.

A systematic literature review of the average IQ of sub-Saharan Africans

Jelte M. Wicherts, Conor V. Dolan a and Han L.J. van der Maas a

a Department of Psychology, Psychological Methods, University of Amsterdam, Roetersstraat 15, 1018 WB Amsterdam, The Netherlands

Received 8 October 2008; revised 6 May 2009; accepted 12 May 2009. Available online 9 June 2009.

Abstract

On the basis of several reviews of the literature, Lynn [Lynn, R., (2006). Race differences in intelligence: An evolutionary analysis. Augusta, GA: Washington Summit Publishers.] and Lynn and Vanhanen [Lynn, R., & Vanhanen, T., (2006). IQ and global inequality. Augusta, GA: Washington Summit Publishers.] concluded that the average IQ of the Black population of sub-Saharan Africa lies below 70. In this paper, the authors systematically review published empirical data on the performance of Africans on the following IQ tests: Draw-A-Man (DAM) test, Kaufman-Assessment Battery for Children (K-ABC), the Wechsler scales (WAIS & WISC), and several other IQ tests (but not the Raven's tests). Inclusion and exclusion criteria are explicitly discussed. Results show that average IQ of Africans on these tests is approximately 82 when compared to UK norms. We provide estimates of the average IQ per country and estimates on the basis of alternative inclusion criteria. Our estimate of average IQ converges with the finding that national IQs of sub-Saharan African countries as predicted from several international studies of student achievement are around 82. It is suggested that this estimate should be considered in light of the Flynn Effect. It is concluded that more psychometric studies are needed to address the issue of measurement bias of western IQ tests for Africans.

Keywords: Group differences; Black-White differences; Flynn Effect; Race differences; Cross-cultural comparison; National IQ

Find entire study here: http://wicherts.socsci.uva.nl/wicherts2009.pdf"

 

[Phenelzine]

Intelligence
Volume 38, Issue 1, January-February 2010, Pages 30-37
doi:10.1016/j.intell.2009.11.003
Copyright c 2009 Elsevier Inc. All rights reserved.

The dangers of unsystematic selection methods and the representativeness of 46 samples of African test-takers

Jelte M. Wicherts, Conor V. Dolan a and Han L.J. van der Maas a

a University of Amsterdam, The Netherlands Received 13 October 2009; accepted 6 November 2009. Available online 3 December 2009.

Abstract

In this rejoinder, we criticize Lynn and Meisenberg's (this issue) methods to estimate the average IQ (in terms of British norms after correction of the Flynn Effect) of the Black population of sub-Saharan Africa. We argue that their review of the literature is unsystematic, as it involves the inconsistent use of rules to determine the representativeness and hence selection of samples. Employing independent raters, we determined of each sample whether it was (1) considered representative by the original authors, (2) drawn randomly, (3) based on an explicated stratification scheme, (4) composed of healthy test-takers, and (5) considered by the original authors as normal in terms of Socio-Economic Status (SES). We show that the use of these alternative inclusion criteria would not have affected our results. We found that Lynn and Meisenberg's assessment of the samples' representativeness is not associated with any of the objective sampling characteristics, but rather with the average IQ in the sample. This suggests that Lynn and Meisenberg excluded samples of Africans who average IQs above 75 because they deemed these samples unrepresentative on the basis of the samples' relatively high IQs. We conclude that Lynn and Meisenberg's unsystematic methods are questionable and their results untrustworthy.

Keywords: Systematic literature review; National IQ; Group differences in IQ

Find entire study here: http://wicherts.socsci.uva.nl/wicherts2010AFRrejoinder.pdf"

 

[Phenelzine]

Learning and Individual Differences
Article in Press, Corrected Proof - Note to users
doi:10.1016/j.lindif.2009.12.001
Copyright c 2009 Elsevier Inc. All rights reserved.

Raven's test performance of sub-Saharan Africans: Average5 performance, psychometric properties, and the Flynn Effect

Jelte M. Wicherts a, Conor V. Dolan a, Jerry S. Carlson b and Han L.J. van der Maas a

a Department of Psychology, Psychological Methods, University of Amsterdam, Roetersstraat 15, 1018 WB Amsterdam, The Netherlands

b University of California, Riverside, United States

Received 19 May 2009; revised 19 November 2009; accepted 3 December 2009. Available online 16 December 2009.

Abstract

This paper presents a systematic review of published data on the performance of sub-Saharan Africans on Raven's Progressive Matrices. The specific goals were to estimate the average level of performance, to study the Flynn Effect in African samples, and to examine the psychometric meaning of Raven's test scores as measures of general intelligence. Convergent validity of the Raven's tests is found to be relatively poor, although reliability and predictive validity are comparable to western samples. Factor analyses indicate that the Raven's tests are relatively weak indicators of general intelligence among Africans, and often measure additional factors, besides general intelligence. The degree to which Raven's scores of Africans reflect levels of general intelligence is unknown. Average IQ of Africans is approximately 80 when compared to US norms. Raven's scores among African adults have shown secular increases over the years. It is concluded that the Flynn Effect has yet to take hold in sub-Saharan Africa.

Keywords: Black-White differences; Cognitive abilities; Cross-cultural comparison; Measurement equivalence; Measurement invariance

Find entire study here: http://wicherts.socsci.uva.nl/wichertsRavenAfr2010.pdf"

 

[Evo]

Thanks Phenelzine for the updates, we stopped discussions on racial discrimination in IQ tests some time ago due to the load of misinformation. This one must have fallen through the cracks.