Rushton's assertion that there was some genetic influence is still not clearly answered with this article, simply dismissed.
It is clear that environmental variables affect g-loaded test scores (one example showed that black children raised in white households test higher than black children raised in black households on average) almost always related to family income, but there is still a weird small percentage that just can't be explained away.
That is the genetic factor that Ruston and others believe exist. For example, white and black children raised from birth in the same household (predominantly white or black household, either one) have this weird gap where the white kids test better on g-loaded assessments.
SAT scores are positively correlated to g-loaded test assessments. The College Board's 2005 SAT data shows a 10 point combined advantage for white kids with family income under $10,000 over black kids with family income over $100,000!
I have no idea the reason behind that leftover unexplained gap. I have never read an article from the genetic or environmental side that adequately explained it in context of the obvious difference that environment makes.
If someone was trying to study the genetic inheritance of intelligence, you would think he or she would want to look at more uniform groups than American blacks and American whites. Given the considerable amount of immigration and intermarriage modifying these group over time, both would appear fairly mixed with "stock" beyond even the European and the African. And Europe and Africa are wide, varied areas to begin with.
Rushton (2012) asserted that the fact
that Black performance falls further behind
White performance on subtests and items
that have a higher g loading is an indication
of a genetic contribution to the Black/
White IQ gap. He believes that a genetic
hypothesis about the origin of the racial IQ
gap would predict this pattern of larger
differences for more heritable, heavily gloaded
items, and that environmental ones
would not. This belief is mistaken. The
construct of g would have no significance if
it were not a measure of cognitive complexity.
If a group is environmentally disadvantaged,
its performance in comparison
to nondisadvantaged groups will be greater
on more complex tasks than on less complex
ones. If you have not played basketball
for many years, your performance will
be closer to what it was previously for
layups than for fade-away jump shots.
Disregarding the problematic use of (1) "groups" solely defined as [race]; and (2) IQ as equivalent to [intelligence]; the <logical> extension of the analysis with the words <in origin> as used in the title is specious. [#,$,!]
________
[#] ie. Logically ok would be Group differences in IQ are best understood as an [having an environmental component].
=edit=
[$] Its logically possible (and most likely correct) that there are N dimensions to intelligence that are consistent in simultaneity (and while still excluding race). EG, including non-racial defined genetic group variation and environmental factors could both have measurable deterministic impacts on outcomes, of order of magnitude equivalent value. Its problematic to assert that the "origin" of [xyz] intelligence is an either/or hypothesis, when its most likely a complex composite. For obvious reasons.
[!] Environmental impacts, once established, cannot then simutaneouly be assumed as a neutral error variable (ie, with vanilla-stochasitic distribution). Certainly not without micro-analytic support. The latter is not evident / nor consistent with (1) or (2). Nor the use of basketball analogies.
One of the best authors on this subject other than the joint authors of the brief reply article submitted here is Jelte Wicherts, who has the especially Internet-friendly habit of putting most of his papers up on his faculty website so that readers who can't punch through paywalls can still read them.
(Scroll down for live links to most of Turkheimer's recent papers, including several current classics.)
Lars Penke is another researcher who shares most of this papers, many of which are co-authored with star researchers on IQ or on human behavior genetics.
AFTER EDIT: Following up on joe_the_user's comment, also a top-level comment, I should point out that the United States Census Bureau has consistently disavowed that "race" categories in the United States have anything to do with biology or genetics.
"The U.S. Census Bureau collects race data in accordance with guidelines provided by the U.S. Office of Management and Budget (OMB), and these data are based on self-identification. The racial categories included in the census questionnaire generally reflect a social definition of race recognized in this country and not an attempt to define race biologically, anthropologically, or genetically. In addition, it is recognized that the categories of the race item include racial and national origin or sociocultural groups. People may choose to report more than one race to indicate their racial mixture, such as 'American Indian' and 'White.' People who identify their origin as Hispanic, Latino, or Spanish may be of any race."
"The race categories included in the census questionnaire generally reflect a social definition of race recognized in this country and are not an attempt to define race biologically, anthropologically, or genetically. In addition, it is recognized that the categories of the race question include race and national origin or sociocultural groups."
An earlier statement by the Census Bureau for reports on the year 2000 census
says, "The concept of race as used by the Census Bureau reflects self-identification by people according to the race or races with which they most closely identify. These categories are sociopolitical constructs and should not be interpreted as being scientific or anthropological in nature. Furthermore, the race categories include both racial and national-origin groups.
"The racial classifications used by the Census Bureau adhere to the October 30,1997, Federal Register Notice entitled,"Revisions to the Standards for the Classification of Federal Data on Race and Ethnicity" issued by the Office of Management and Budget (OMB)."
In other words, the professional demographers who work on the United States Census claim only to be following the law, not to be practicing biological, anthropological, or genetic science when they ask for self-identification of "race." That claim has continued through two different presidential administrations as the bureau conducted two successive decennial censuses and numerous community surveys. The Census Bureau practice is based on regulations from the Office of Management and Budget (OMB), which were announced on 30 October 1997
to take effect no later than 1 January 2003 for data collection by all federal agencies. The summary of comments on the 1997 regulations makes clear that not all Americans are united in agreeing with the current set of categories. (The categories used by the federal government have changed several times in my lifetime.) The distinct differences between the categories used in the United States and those used in any other country in the world should make clear that categories are indeed "sociopolitical constructs and should not be interpreted as being scientific or anthropological in nature." I bring this up because several recent threads here on Hacker News have interpreted "race" categories as if they have genetic or anthropological meaning, which they do not.
The long story about how to think carefully about race and ethnicity in the human population can be found in the books recommended for first reading in a Wikipedia user bibliography "Anthropology, human biology, and race citations bibliography"
> consistently disavowed that "race" categories in the United States have anything to do with biology or genetics.
They disavow it because it's politically poisonous any other way. But it's obvious that race is genetic - all you have to do is look at the physical, and heritable, characteristics.
And despite the "disavowment", practically speaking, most people are the genetic race they claim.
The use of race as a proxy for uniform genetic variation is silly. It follows (awkwardly) you cannot reject the hypothesis that genetics are determinate, by rejecting analysis on race-based data. But that is only the tip of the iceberg of problems here.
There is a logical problem and a data problem. The data problem is that race is not a proxy for genetic variation, per-se (mixed data). The logic problem is that rejecting race as a hypothetical causal relationship does not reject genetic variable (by proxy, since proxy=false). Furtermore, rejecting the alternative hypothesis (ie, genetics) does not default to a single variable solution (ie Envronment or Genetics is origin). You cannot reject the hypothesis that they BOTH are important. Logically, they are not binary, per observation.
The takeaway is that the headline is a problem. Reducing Environment to a one of many simultaneous causal factors trivializes it.
Rejecting genetic determinants as having significant explanatory power is counter-thetical to Evolution. This is an orthogonal point, but its important. The Environment being "origin" implies that mate selection is irrelevant to inherited/expressed/realized intelligence. Which is clearly false. As a observed or as a logical matter.
Think of a car engine. Every manufacturer will have defects (manufacturing tolerances). And poor maintenance will cause every engine to eventually fail (ie, dont change the oil). So, (1) design is not determinate of performance fully; and (2) environment can determine ultimate success/failure. It does not follow that all egines have the same layout for internal cumbustion. Nor does it follow that when working at full capacity/optimim tune they will have the same power output. Nor can we conclude anything about the suspension or the chassis performance, etc. But nor does it follow that ultimate performance (of the complex system) cannot still be competitive (at least in certain environments, etc). Cars of various design are competitive at road-rally, for example.
While genetics is certainly not 100% explanatory, it simply is and must be a component in the "origin of intelligence". Unless you are a crazy-tea-party-sceptic-of-evolution.[sic]. So, this is problem for the intelligensia/left if they want to divorce inherited/genetics from the disucussion.
The problem is the level of abstaction. We know genetics matters by species. We know genetics matters by (nuclear) family. What are the in-between levels (if any) that also matter? That is where things get murky and messy (politically, logically, and otherwise). At some stage, this might also be analysed of as a question of entropy. ie, if two smart people get married and their kids are x/n likelt to be smart, at what stage in replication do they revert to x/n= population average. If ever? What if their is persistent top-quartile genetic pairings (ie, adding selective-diversity, etc). What if their is a random sample from the population? Are the two vcases the same or different? how do you tell/test? etc.
None of which should give cover for thinking without due clarity, however.
It is clear that environmental variables affect g-loaded test scores (one example showed that black children raised in white households test higher than black children raised in black households on average) almost always related to family income, but there is still a weird small percentage that just can't be explained away.
That is the genetic factor that Ruston and others believe exist. For example, white and black children raised from birth in the same household (predominantly white or black household, either one) have this weird gap where the white kids test better on g-loaded assessments.
SAT scores are positively correlated to g-loaded test assessments. The College Board's 2005 SAT data shows a 10 point combined advantage for white kids with family income under $10,000 over black kids with family income over $100,000!
I have no idea the reason behind that leftover unexplained gap. I have never read an article from the genetic or environmental side that adequately explained it in context of the obvious difference that environment makes.