What is IQ?

An intelligence quotient (IQ) is a total score derived from several standardized tests designed to assess human intelligence. There are many different types of intelligence tests. Some of the most common are the Wechsler Adult Intelligence Scale (WAIS) and Raven's Progressive Matrices. IQ is distributed normally across the population, which can be represented by a simple bell curve.

What is g?

g, or the General Intelligence factor), refers to the existence of a broad mental capacity that influences performance on cognitive ability measures. It is what IQ tests measure. Some IQ tests and subtests measure g more or less than others, and we say certain tests are more or less "g-loaded" depending on how much they measure g:

The g loadings of mental tests are always positive and usually range between .10 and .90, with a mean of about .60 and a standard deviation of about .15. Raven's Progressive Matrices is among the tests with the highest g loadings, around .80. Tests of vocabulary and general information are also typically found to have high g loadings.

Yes, IQ/g reflects "intelligence", and IQ tests measure it well. This can be validated by correlates with IQ scores and other proxies for intelligence (like peer ratings) and life outcomes. Even wikipedia acknowledges that g is an excellent predictor, especially of job performance:

https://en.m.wikipedia.org/wiki/G_factor_(psychometrics)

The practical validity of g as a predictor of educational, economic, and social outcomes is more far-ranging and universal than that of any other known psychological variable. The validity of g is greater the greater the complexity of the task.

Research indicates that tests of g are the best single predictors of job performance

If you want to look at individual studies, Tarmo Strenze reviewed a series of longitudinal ones that compared how various life factors correlated with education level, income and occupation. IQ correlates more strongly with all three of these variables than grades, SES index, parental education, or parental income. That's just one of many examples that demonstrate the validity of IQ. In fact, there is more empirical evidence demonstrating the validity of g (including intractable, heritable racial differences) then there is virtually anything else in all of psychology. There is just one g (and still just one g) so if someone gets into topics like "multiple intelligences" etc. its probably a waste of your time. Distinguishing between IQ/g isn't often practically necessary, but it is on topics like the "Flynn Effect".

What is heritability?

*Heritability is a statistic used in the fields of breeding and genetics that estimates the degree of variation in a phenotypic trait in a population that is due to genetic variation between individuals in that population.

In other words, heritability is a mathematical estimate that indicates an upper bound on how much of a trait's variation can be attributed to genes. Heritability ranges from 0-1 (0-100%) and varies by age, and changes depending on where/when you are measuring IQ. The wikipedia article on the heritability of IQ is actually pretty good:

Various studies have found the heritability of IQ to be between 0.7 and 0.8 in adults and 0.45 in childhood in the United States. It may seem reasonable to expect that genetic influences on traits like IQ should become less important as one gains experiences with age. However, that the opposite occurs is well documented. Heritability measures in infancy are as low as 0.2, around 0.4 in middle childhood, and as high as 0.8 in adulthood.

"The experts" on IQ can be divided into two main camps: The Hereditarians, who believe IQ differences are a combination of environment and genes (usually 50/50 as a "default") and the Egalitarians, who believe differences are 100% due to environment.

Key Hereditarians: Arthur Jensen (d. 2012), Phillipe Rushton (also d. 2012), Richard Lynn, Linda Gottfredson

Key Egalitarians: James Flynn, Richard Nisbett, Eric Turkheimer

Basically the last three are always the ones the media talks to about race differences in intelligence, because they are willing to obfuscate/lie and cherry-pick evidence to align with the globohomo orthodoxy. The best example of this is Eric Turkheimer's hilarious and infuriating interview with David Pakman that AltHype reviews (highly recommended viewing). If ever someone references one of these authors in regards to racial gaps in IQ, you can be assured that they are full of shit - you just have to dig deeper to figure out why. Note also that the egalitarian position it at this point almost completely indefensible, so we know that this "camp" will not outlive the "researchers" who push for it.

Clarification: Egalitarians believe genes play 0 role in intelligence differences, but everyone acknowledges the racial gaps exist. That isn't controversial anywhere. The egalitarians simply believe socioeconomic factors explain the gaps (but theyve never sufficiently done this). Also, everyone acknowledges environment matters, but disagree to the extent that it does. You do not need to find the genes to infer heritability, and even the egalitarians know this (but they'll mislead you anyways - see Turkheimer/AltHYpe vid)

Surveys of Expert Opinion

Snyderman and Rothman's 1984 Survey (published 1987) (Graph)

Mainstream Science on Intelligence - 1994

8 "The bell curve for whites is centered roughly around IQ 100; the bell curve for American blacks roughly around 85; and those for different subgroups of Hispanics roughly midway between those for whites and blacks. The evidence is less definitive for exactly where above IQ 100 the bell curves for Jews and Asians are centered"

14 Heritability estimates range from 0.4 to 0.8 ... indicating genetics plays a bigger role than environment in creating IQ differences"

The history of this statement is very interesting, and this brief editorial by Gottfredson is a very good read. Gottfredson put this together in response to media and public outcry following the publication of The Bell Curve. She was only given two weeks to turn the article around and get signatures (this is pre-internet era) and was published begrudgingly by the Wall Street Journal editorials editor (((David Brooks)))

Rinderman, Coyle and Becker 2013 (Graph)

Note that the majority view by far is "mix of genes and environment" which makes most researchers hereditarians.

best references and sources for debate/education

Richard Lynn - Race Differences in Intelligence (2006). This source is great because it has IQ studies from all over the world organized nicely in tables by native populations and even hybrids. Very good reference. Lynn has other works like this, but I have never seen them in completeness on the internet before. Its a bit dated, but holds up well. There are criticisms of the Sub-Saharan African IQ numbers which I will address later

Rushton and Jensen - "Thirty Years of Research on Race Differences and Cognitive Ability" (2005)

This work is a great overview of the history of intelligence research and racial differences (Section 3). Other good references in this document:

p. 251 Demonstrating the "Wilson Effect" (increasing heritability with age), >0.8 in adulthood

p.263 "regression to the mean"

p. 272 Table 5 sums up all the statistical evidence for various explanations for IQ differences, and how egalitarians have repeatedly failed to validate their hypotheses

Linda Gottfredson - Why g Matters: The Complexity of Everyday Life (1997)

Linda Gottfredson - The General Intelligence Factor (1998)

Thomas Bouchard - Genetic Influence on Human Psychological Traits (2004)

Good overview of the findings on genetics and psychology. All psychological traits are highly heritable. See Table 1

Rushton and Jensen - Race and IQ: A Theory-Based Review of the Research in Richard Nisbett’s Intelligence and How to Get It (2010)

This is a thorough debunking of common egalitarian talking points and cherry-picked data. This was in response to Nisbett's terribly misleading book published in 2009. If some detractor is spewing BS about the "Flynn Effect" or "Gaps converging" this is your go-to

Note: The site "Brainstats.com" is not a reliable reference. This site claims to reference Lynn's work but intentionally ships in bad studies that overstate IQs for some countries, and understate IQs for others (and don't cite the source). The most glaring example of this is an IQ of 91 for Sierra Leone that I debunked in this post. I don't know why they do this, but they probably just want your money for a """free""" IQ test.

Average IQ by Race (Also see Table 13.1 In Race Differences by Lynn)

Ashkenazi Jews: 110

East Asians: 105

Europeans: 100

-Note: Some European populations appear to have lower IQs, specifically southern Slavs (90) and the Irish (93-97)

Hispanics: 92 (varies a lot depending on % white/african admixture)

Turks: 90

Southeast Asians: 90

Indians: ~85-90 (probably varies a lot by caste in India)

Amerindians: 86

Arabs/NA Africans: 85

US blacks (20% white on average): 85

SS Africans: <75, genotypic IQ probably ~80

Australian Aboriginals: 62

Now we'll look at some common BS from Egalitarians

Using Only Children

A classic tactic that egalitarians employ is making thier case with only IQ data from samples of children. IQ scores are much more variable/malleable at young ages and heritability is much lower.

Scarr-Rowe Hypothesis

An idea developed by Sanda Scarr in the early 1970s and replicated by David Rowe in 1999, this hypothesis is that heritability varies a lot by socioeconomic status (SES). The argument was that wealthier families have higher heritability, implying that if only the poorer families had more wealth, they could reach their genetic potential for higher IQs. This is a favorite of Turkheimer, despite his 2003 findings failing replication four times - [1] [2] [3] [4]. Failed in the UK as well. This meta-analysis allegedly finds some evidence for it, but I haven't read it myself. See also that AltHype vid on Turkheimer I already linked

Flynn Effect

This is the most common argument from detractors - rising IQ scores over time aka "The Flynn Effect." Raw IQ scores have increased over time, but the effects are not on g. The majority of the gains are probably related to longer and better education. There have probably been real gains in certain countries/areas owing to nutrition. However, most recent evidence suggests the [Flynn Effect has ended]((https://en.wikipedia.org/wiki/Flynn_effect) or even reversed for certain countries. Most of the reversals have occurred in Western nations, which we would expect given that they have imported irresponsible amounts of low-IQ people from Africa and the Middle-East. See also Rindermann, Coyle & Becker, 2013 pages 26-27 for expert opinions on the Flynn Effect.

Flynn himself does not even argue that the Flynn Effect is relevant to racial gaps:

*“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

Flynn even acknowledges he himself did not discover the effect:

"Richard [Lynn] is correct. Calling massive IQ gains over time the “Flynn Effect” was an accident of history, a label Charles Murray coined in The Bell Curve in 1994. It is not a verdict a court would have been likely to hand down if it had an eye for the historical record."

From Rushton and Jensen's A Theory based Review..

Moreover, when Nisbett favorably cited Flynn’s [18] most recent book, he neglected to mention that Flynn had apparently changed his mind about the relation between g and the Black-White gains. While Flynn still maintains that the race differences are mostly environmental in origin, he now agrees with Rushton and Jensen [8] and disagrees with Nisbett [5], as well as his own former opinion [32]:

Rushton & Jensen: That Black-White IQ differences are more pronounced on the more g loaded and more heritable components of tests does indeed imply the differences are partly genetic in origin. However, it is a false claim that g and inbreeding depression correlate with the secular rise in IQ. We review the tortured history of this claim and in the process find we have eliminated the Flynn Effect as a reason to expect any narrowing of the Black-White differences.

Racial IQ Gaps are NOT Converging

Team Egalitarian likes to make claims that the IQ gaps are converging, usually citing 0.33 SD gain for Blacks over the last 50 years. Good examples of this are Richard NIsbett's Intelligence and how to Get It and this paper by Nisbett, Flynn, and Turkheimer. This has been thoroughly debunked in "A theory Based Review*" by Rushton and Jensen:

Rushton and Jensen: In fact, there is very little evidence of any significant narrowing of the Black-White IQ gap. Rushton and Jensen [25] disputed Dickens and Flynn’s [24] claim that Blacks gained 5.5 points by showing that Dickens and Flynn excluded several tests and then “projected” forward by multiplying a small gain from their highly select group of tests by more years than were available for most of the data. Dickens and Flynn excluded the Wonderlic Personnel Test, which showed a gain of only 2.4 points for Blacks between 1970 and 2001; the Kaufman Assessment Battery for Children (K-ABC), which showed a loss of 1 IQ point for Blacks between 1983 and 2004; the Woodcock-Johnson test, which showed a zero gain for Blacks; and the Differential Ability Scale, which showed a gain of only 1.83 points for Blacks between 1972 and 1986. Moreover, even the test data they did present did not directly support their conclusion. Simple arithmetic, rather than a multiplied projection, yielded a mean gain for Blacks of 3.4 points (23%), not the 5.5 points claimed (37%). Including the aforementioned tests reduced the gain from 3.4 to 2.1 points (14%). Nisbett does not explain how he arrived at an overall Black gain of 4.5 IQ points (30%) after including the four small (or negative) gain tests. Simple arithmetic applied to all eight tests yielded a mean gain for Blacks of only 2.1 points (14%). Other researchers have also failed to find a significant narrowing of the Black-White gap over the 30 years covered by Dickens and Flynn (i.e., from 1972 to 2002). For example, Murray [26, 27] concluded there was “no narrowing” in two independent studies. In the first, he found no narrowing in either verbal IQ or achievement test scores for children born to women in the 1979 sample of the National Longitudinal Survey of Youth. In the second, he found no narrowing for 6- to 65-year-olds in the Woodcock–Johnson standardizations of those born in the last half of the 1960s and early 1970s. When Roth et al. [9] confirmed the 1.1 SD difference in a sample of 6,246,729 corporate, military, and higher education testees, they also addressed the question of whether the differences were decreasing. They concluded that any reduction was “either small, potentially a function of sampling error…or nonexistent for highly g loaded instruments” [9, p. 323, our italics].

On the second paper, in Mean Black-White IQ Differences Predicted by Heritable g

Comments on the original article, "Intelligence: New findings and theoretical developments," by R. E. Nisbett, J. Aronson, C. Blair, W. Dickens, J. Flynn, D. F. Halpern, and E. Turkheimer... The present authors assert Nisbett et al were incorrect when they claimed that between 1972 and 2002 there was a 5.5-point narrowing of the 15-point IQ gap between Blacks and Whites (p. 146). In doing so, they sidestepped Rushton and Jensen's (2006) objections to Dickens and Flynn's (2006) evidence and failed to include subsequent evidence. The present authors maintain that Nisbett et al failed to describe accurately how heritable g provides evidence of a significant genetic contribution to Black-White differences. The present authors claim Nisbett et al obscured the topic by invoking alleged age and social class interactions and adoption studies of very young children.

Pollutants

Some pollutants and environmental effects do impact IQ. Lead, Mercury poisoning and Iodine deficiency in particular have been shown to lower IQ scores. The biggest problem with this as an explanation is that pollution cannot explain the bulk of racial gaps. Blacks

Criticisms of Lynn's Sub-Saharan African numbers

Dutch team Wicherts, Dolan, and Van Der Maas criticized Richard Lynn's work on Sub-Saharan IQ. They claimed that Lynn used samples that were diseased, illiterate and not-smart-enough Africans, and think the SS African IQ is 80, not 70. I wrote about this more here, but the TL;DR of this is that these criticisms, if with merit, simply don't matter. Lynn believes that SS Africans have genotypic IQs of 80, and accepting an IQ of 80 for SS Africa kills the egalitarian - it would imply racial differences in intelligence are 100% due to genetics and the environment is worth almost nothing

Find the Jean!

We don't need to do this, but "OK." We found (some of) the genes

Basic Questions for Egalitarians that expose their position as highly dubious

• How do egalitarians explain that race and intelligence follows the same pattern all over the world? (e.g., Black < White < Asian?) If blacks have low IQs due to "racism" or some other factors, why do these forces act on non-white races so differently and cause them to have different scores, some even higher than whites?

• If we believe in evolution, and the evolutionary history of humans, then why should we believe human populations all evolved the same capacity for intelligence? Especially if we blieve that human racial differences like skin color, hair texture, or other physiological traits are the result of natural selection, why should we expect evolution stopped at the neck?

• How do egalitarians explain other measured differences in cognitive ability and anthropology that follow the same pattern? (See table 3 in "30 Years")

• How do egalitarians explain regression to the mean for parent-offspring IQ?

• Why do the average IQs of mixed race people always fall between the IQs of the races theyre composed of?