Black/White IQ Gap Is Heritable

Before addressing the primary topic of this post, which I will restate in layman's terms when I am prepared to move on to that topic, it's necessary to dispel IQ denialism, a phenomena too prevalent to ignore; those thoroughly familiar with HBD, short on time, or simply impatient, are welcome to skip this overview. Credit to Ryan Faulk of The Alternative Hypothesis with being the impetus for this, this is an elaboration on a subject he broached in one of his videos.

*IQ Test Reliability*
"Test-retest reliability of the Test of Nonverbal Intelligence (TONI) was investigated. Fifty students randomly selected from first and second grades were administered Form A and Form B of the TONI on two occasions 3 weeks apart. Test-retest correlation coefficients were calculated for all 50 subjects. The results showed high test-retest reliability: Correlation coefficients were .89 (Form A) and .83 (Form B). Parallel form reliability was also high: Form A correlated with Form B .88 on the first administration and .86 on the second administration."
http://www.sciencedirect.com/science/article/pii/002244059090024

A perfect correlation would be 1.0 (i.e. identical scores across time), anything greater than a .70 correlation is, by definition, a "strong correlation."
"The WAIS is one of the most widely used means for assessing intelligence, yet data on test-retest reliability are scarce. The test-retest IQs of 50 psychiatric patients (mean age 44 yrs) were correlated. The patients were not from any specific diagnostic group. They were included in the sample only because they had been given the WAIS before. The interval between test and retest averaged almost 2 yrs. All test-retest correlations were .90 or over."
https://www.researchgate.net/publication/247434054_A_test-retest_reliability_study_of_the_Wechsler_Adult_Intelligence_Scale

*IQ Test Validity*
Reliability doesn't prove validity. If a researcher was attempting to measure the concept of intelligence by having subjects throw darts on a board, assuming scores were highly similar over time, that would be a reliable test, but it would not be valid because that test has no link to the actual concept of intelligence. The Alternative Hypothesis has done a great job providing evidence of the validity of IQ testing, I won't try to compete: http://thealternativehypothesis.org/index.php/2016/04/15/the-validity-of-iq/

*Restatement of the Initial Claim:*
The evidence that shows genetic differences to be the primary cause of observed differences in intelligence among adult white men, despite the cautions about comparing heritability estimates within groups and between groups, is actually substantial proof that racial differences in intelligence (such as the black/white ~15 point IQ gap) are primarily a result of genetic differences between those racial groups.

Why is this claim so controversial? That is best explained with a cautionary tale involving plants and soil, but first, the concept of heritability itself must be understood. Heritability coefficients tell us the proportion of observed variation that is attributable to genetic differences. It is impossible to provide a heritability coefficient for a single individual, as heritability coefficients tell us how much of the differences between individuals within a specific group at a specific time are attributable to genetic differences. The heritability coefficient of height in well-fed Western populations is about .90, meaning about 90% of observed variation in height is a result of genetic differences, among malnourished groups, height will be much less heritable (e.g. .30 heritable), meaning differences in height in those environments will tend to be primarily a result of differences in environment (nutrition), not genetics. If two groups had all environmental differences that affected their intelligence eliminated, the heritability coefficient of any remaining IQ gap would be 1.0, 100% a result of genetic differences, as there would be no environmental influence left to attribute to the average difference between the two groups. Within a large genetically identical group, height would have a heritability coefficient of 0.00, as all (presumably small) differences in height could only be attributed to environmental differences. A heritability of 0.50 within a group would mean that 50% of whatever observed differences are attributable to genetic differences.

As previously mentioned, IQ is highly heritable among white men, this example is of Russian twins, but there's plenty of similar results for white men in America, or Europe:
"The present study is an investigation of 80 like-sex, Russian twin pairs aged 16–28 years undertaken to replicate and extend the existent research literature on the heritability of cognitive ability in young adults... Additive genetic influences accounted for approximately the same amount of variance in verbal, performance and full-scale IQ data––86%, 84% and 89%, respectively. The results are consistent with the reports from the majority of studies, suggesting an increased heritability and decreased shared environmental influences on IQ variability in adulthood compared to childhood."
http://www.sciencedirect.com/science/article/pii/S0191886903002691

As was explained in the definition of heritability, heritability coefficients are affected by environment. Here is where the cautionary tale comes in, a cautionary tale provided by Richard Lewontin, the man we have to thank for "Lewontin's Fallacy" (look up "A Family Tree in Every Gene" for an explanation and rebuttal of that sophistry, you've probably heard leftists spout the nonsense meme about more diversity within racial groups than between them):
"...Richard Lewontin devised an insightful demonstration to show this. Imagine planting ordinary, genetically diverse seeds into two radically different environments and then allowing them to grow to their full heights. One environment is very deprived, with just barely enough light, nutrients, and water for survival. The other environment is enriched with ideal amounts of light, water, and nutrients. All of the variation in height within each tray must be due to the genetic diversity of the seeds, since the seeds developed in identical environments, and therefore the variation observed in the heights of the plants within a tray cannot be attributed to differing environmental factors. So regardless of the environments in which the plants grew, heritability is 1.0, or 100 percent, within each tray. Yet obviously environmental factors played a large role in each individual tray, so even if heritability is 100 percent, the environment can have very powerful effects on the appearance of a trait. "

Here's why this cautionary tale is irrelevant to human intelligence.

Intelligence affects the "soil" (environment) you choose/help create. This analogy is a complete failure for the heritability of intelligence because the analogy couldn't possibly involve "clever" plants which have a genetic propensity for creating fertile soil which all plants could then thrive in. Here's my own "insightful demonstration" of how Lewontin's was a failure for the heritability of intelligence in humans:

Imagine planting two subspecies of seeds into one tray which is divided by a wall we'll call "the Mediterranean sea and the Saharan desert". Both environments are identical in fertility, and deficient in phosphorous, a nutrient plants need to survive, we'll label phosphorous rich environments "prosperous", the plants north of the Mediterranean sea have, due to prior evolution, an innate tendency to produce phosphorous (based off of other available chemicals) and create a more prosperous environment, enabling more and faster growth, creating a virtuous cycle, whereas south of the Saharan desert, plants strangle each others' roots and never produce phosphorous as it would likely just be stolen and used by a neighboring plant, 30,000 years into this process a Marxist breaks into the greenhouse and shrieks about how the racism of the plants on the northern side of the tray has prevented the darker shaded plants in the southern side from enjoying a prosperous society.

http://thealternativehypothesis.org/index.php/2016/04/15/iq-and-socio-economic-status/
Your IQ is a better predictor of your future socioeconomic status (SES) than your parents', what this means is that intelligence creates "good soil", not the other way around (e.g. a professor with a high income did not become intelligent because he has the income of a professor, he was intelligent enough to become on in the first place due to significant genetic factors combined with an environment that was not particularly deleterious). High intelligence creates good environments, which is why Hong Kong, Japan, and South Korea have been able to achieve great prosperity (despite recent poverty and suffering) and Haiti hasn't. Assuming that people/groups that are poor in intellect *because* they are economically poor is a decision that is motivated by feel good Blank Slate Marxist bullshit, not an impartial observation of the evidence.