American IQ scores have rapidly dropped, proving the 'Reverse Flynn effect'

Honest question that keeps bothering me.

In the absence of reasonably strong natural selection pressure to select for IQ, how could IQ not be falling over time?

It is not. IQ doesn’t measure a kind of intelligence which inherits, and is subject to natural selection (there is even a debate whether such intelligence exists; or at least is of any significant between individuals).

IQ at best measures something that correlates with SAT. And with better education, less exposure to damaging pollutants, etc. it should always be on the rise (as demonstrated by the Flynn effect; an effect which this poor paper desperately tries to refute).

IQ research has always been about proving the superiority of one race over others, this superiority doesn’t exist, but that doesn’t stop these pseudo-scientist from trying. They bend the definition of “intelligence” and device test batteries (and in this case, interpret test battery) in skewed and bias ways to manipulate results like these. Regrettably media outlets like the Popular Mechanics and lifestyle journalists like Tim Newcomb take these researchers at their words and publish their results, despite their results pretty much being lies.

The heritability of IQ is very well established, usually estimated in the 50-80% range. You are fighting an uphill battle here because even if people haven’t seen the scientific evidence this effect is so strong that virtually everybody has seen anecdotal evidence of high IQ parents having high IQ children, but just seem to assert a very heterodox and counter-intuitive position without further elaboration.

It is incredibly arguable if during an obesity crisis if population wide health is actually improving and if population wide health isn’t improving that could certainly contribute to lower IQ. We’re also seeing population wide declines of health in other ways like sperm count. Food is becoming less nutritious as soil depletes. Our fish stocks being about to collapse is going to be another hit against brain health as omega 3s will become rarer in the diet.

I’m not fighting an uphill battle. Ever since The Bell Curve came out, there has been a slow but steady distancing of both psychological research and policy makers from the whole field of IQ research. Modern psychology couldn’t care less about on the heritability factor of IQ, and most policy makers don’t want to touch it with a 10 foot pole. Heck the SAT has even been renamed as they don’t want to be affiliated with anything resembling IQ any more.

The heritability of IQ is only well established within true believers of a pseudo-science tightly linked with the eugenics movement. Most psychologists today believe that the supposed heritability was observed because of bias within the research. And given the people who were doing these research in the 1970s and the 1980s, and their motivation for doing those, there is no question on what these biases were. Some of the researchers went so went quite far in bending the data such that it would fit their narrow—and racist—world view. They tried really hard to define intelligence such that it would make rich white people smarter, they were regrettably successful for far to long, but ultimately failed.

Your anecdotal evidence of high IQ parents (ugh!) having high IQ children is the same anecdotal evidence that sociologists have been describing for decades that high SES parents have high SES children, and is the main reason for why parents with high SAT scores are likely to have children with high SAT scores.

What IQ researchers discovered was basically the same thing that Marx described in 1867, class, however the eugenics were no communists, and instead of providing the simpler explanation, that society rewards the ruling elite, and wealth inherits, the eugenics went all conspiratorial and blamed other races for their perceived decline in society.

The following is my opinion, based on my research:

* IQ is real, measurable and heritable. The evidence for this is overwhelming.

* Nobody argues about the broad heritability of other human traits such as hair/eye color, height, athletic ability and the like.

* The argument over IQ is a consequence of terrible historical experiences with eugenics and racial discrimination. Many have adopted the quasi-religious viewpoint that IQ is not heritable to sidestep the discussion.

* As a consequence, social policy resembles the cycles and epicycles of Ptolemy's cosmology. Namely, all manner of social, economic and historical outcomes which are explained parsimoniously by understanding IQ as heritable are instead attributed to a Rube-Goldberg machine of racism, class warfare and the like.

* Accepting IQ as heritable does not, in an enlightened society, require acceptance of racism or classism, any more than people are forced to discriminate against those who, say, are genetically weaker athletes due to low relative VO2 levels.

* Social policy could be enhanced and better targeted by targeting those at the lower end of the IQ curve with subsidies such as basic income.

* Accepting IQ as real, heritable and measurable represents one of the only paths out of the present morass of corrupt political patronage programs around specific groups, just as rejection of Ptolemy's worldview enabled turning away from the demon-haunted world of religion.

People say IQ is "heritable" all the time, but it's easy to say that without giving any evidence that one understands what heritability means. Lots of things are heritable and not genetically determined, and there are things that are absolutely genetically determined that aren't really heritable.

If you're going to build a whole chain of logic, one that attempts to solve racism somewhere in the middle and ends with the "demon-haunted world of religion", it's useful to clearly define your terms first.

I was using "heritable" as a synonym for "genetically determined." Thanks for the clarification. To be a bit more specific, it is obviously possible to environmentally lower someone's IQ from their genetic potential. Examples include lead poisoning and denial of basic nutrition. Similarly, you can environmentally prevent someone from being able to run as fast as they might genetically have been able to by injuring their legs in various ways in childhood.

in both of those cases, as in all things genetic, expanding the ceiling is a far different matter. There is no known treatment I could have been given to enable me to run a 2 hour marathon. Similarly, there is no known way to cause a 100-IQ person to reliably test at a 140 IQ.

That said, progress is being made on artificial intelligence and genetics, so that could all change.

I don't understand how your logic holds together once you concede that heritability doesn't mean "genetically determined". This is the problem with lots of arguments about "heritability" of IQ; heritability is simply the ratio of genetic effects to the total variance in a population. If we're asking whether IQ is genetic, then saying that something is "highly heritable" is simply restating the question.

(I find it helpful to remember that lipstick-wearing is highly heritable despite zero genetic determination, and number of toes isn't very heritable at all despite total genetic determination.)

In particular, you can't convincingly go from discussing the seemingly profound effects acknowledging IQ heritability will have on racism, in order to avoid "demon-haunted" religious arguments, to a shrug and a handwave about genotypic (and epigenetic) effects vs. environmental effects. With due respect to your good-faith attempt to establish a logical baseline to this whole situation, the demons are haunting your argument, not those of people who'd push back on it.

It's an earlier rebuttal and you can find more precise and current ones now, but Ned Block's heritability piece is a good starting point for this stuff (you can just Google for "ned block heritable", the SERP will be dozens of links to it.)

We've reached the maxiumum thread depth, but in brief: Your two comments directly contradict one another. You wrote:

> I don't understand how your logic holds together once you concede that heritability doesn't mean "genetically determined".

And you wrote:

> You literally just said that you were using "heritability" as a synonym for "genetic determination". No, you can't do that.

I'm not sure which sentence I'm supposed to take as you saying what you mean, but yes, I can say I'm using "heritability" as a synonym for "genetic determination."

And, of course there is plenty of evidence that IQ is genetic. That's most of the reason why it's become a taboo area of research. If people were sure it was a waste of time, they'd just tell researchers to go ahead and check. Instead, they taboo it because they're afraid of what it would mean for their view of society if it turned out to be true, which it surely is.

As I mentioned in another thread, your claim that it's not genetic should not be the prior here. That would be like me claiming that people's maximum height being environmental should be the prior. It's just preposterous. Of course physical traits are primarily genetic. The brain is a physical object, therefore its structure is primarily genetic.

I mean, you can say it, but (a) you're flatly and obviously wrong, and (b) what you're saying is extremely misleading, because there is a lot of research demonstrating heritability of IQ, and none of it establishes genetic determination of IQ. To redefine such an important term flips the status bit from good faith discussion to something else. I'd like to assume good faith! So: reconsider.

Later

You've extensively edited your comment. In response to those edits: if you look back at my comments, I think you'll see that I haven't made a claim about genetic determinism at all, only that the evidence you've presented doesn't support it.

Nothing can ever establish that intelligence is determined by genetics, because environment always happens to you after genetics do - if it's not affecting your intelligence that just means you've got the wrong environment. (Other factors come into causation when you hold the environment constant, but nobody ever says that!)

Or in other words, the reason you're not smarter is because nobody's invented a surgery to make you smarter yet. And the reason you're not less smart is that nobody's hit you over the head with a rock. If either of those scenarios happened, your ancestry wouldn't get to object much.

Great arguments. Can you give an example of an environment that would enable a cat to play chess as well as me? No? Then there must be a genetic component to IQ.

Why is your ability to play chess an example of intelligent behavior but not your cat’s ability to jump on furniture?

If you want a theory of intelligent to include a notion of general intelligence which can be measured, you must be able to defend which aspects of behavior falls in the category of intelligent, and which not.

Playing chess and jumping on furniture both require plenty of cognitive skills, and brain functions to work together and produce a singular outcome, both are goal driven, both takes years of practice, both have varying skill levels.

Now the cognitive functions these skills require may both be inherited, you may even find the specific genes which encodes either behavior (and name them the furniture jumping gene and the chess playing gene if you will). However when you assign chess playing as intelligent but not furniture jumping, then you’ve made an arbitrary choice, which you need to justify. (You also have the option of not defining intelligence to begin with; which what I personally would pick).

But more importantly, even if you find your justification, you’ve only found one gene of intelligence which inherits, you haven’t found a gene for general intelligence, so you haven’t shown that intelligence is determined by your genes, only the ability to play chess well.

Then when you find all the genes for all behavior you consider intelligence, you still haven’t shown that they co-inherit with each other, that is, you haven’t shown that people with the chess playing gene tend to also have the sudoku solving gene, and the IQ test taking gene, etc. For there to be a single general intelligence, and for this general intelligence to be determined by genetics, than this is what is required. Unless of course general intelligence is a real thing and there is a gene for it which allows you to play chess better than others, solve Sudoku faster than others, answer more questions on IQ tests correctly, etc. But this is a rather extraordinary claim, don’t you think?

I actually like the nuance of your point. I think you're aiming at a certain circularity in the definition of intelligence. Namely, we know that there are a set of cognitive abilities which set certain people apart in society as those who can advance modernity. We find those abilities intriguing, we investigate them, and we measure them and assign them a name. Then, we notice that people who test well for those abilities do well economically and otherwise in society. The whole situation is somewhat tautological.

I agree with that reasoning! We defined intelligence the way we do because it "works." If jumping on chairs were what advanced modernity, we would test for that instead. And, that too would "work" because it would surely be a marker for people who were likely to be successful in life.

Social sciences aren't going to be able to provide specific answers to your questions in the near term. No, there is no single gene or trait that codes for "intelligence" as we define it. But, that does not mean we can't come up with intelligence tests which correlate strongly with that definition and also correlate strongly with various measures of success in life. Such measures also correlate strongly with society-wide success (measured by a group's progress along the tech tree).

Being born to a rich family is a way better correlator of what you describe as “success”. Why than not construct a class quotient (CQ) and use that instead? Surely if the only thing it needs to do is work as a predictor of “success”, than there are simpler metrics than IQ.

Actually I’m gonna repeat a couple of paragraph from the first post you responded to: https://news.ycombinator.com/item?id=35517130

> Your [faeriechangling] anecdotal evidence of high IQ parents (ugh!) having high IQ children is the same anecdotal evidence that sociologists have been describing for decades that high SES parents have high SES children, and is the main reason for why parents with high SAT scores are likely to have children with high SAT scores.

> What IQ researchers discovered was basically the same thing that Marx described in 1867, class, however the eugenics were no communists, and instead of providing the simpler explanation, that society rewards the ruling elite, and wealth inherits, the eugenics went all conspiratorial and blamed other races for their perceived decline in society.

High SES correlates with IQ, so you're just measuring the same thing, going round and round in circles. You're just grasping at straws trying to find some arguments that allow you to invalidate the obvious null hypothesis. You're doing it for political reasons, and it's totally obvious.

Obviously high SES doesn't measure the same thing as IQ, and genetically unrelated children are brought up identical SES environments all the time. This argument doesn't even cohere logically.

(For what it's worth: research suggests that adopting low-SES children into high-SES households is associated with as much as an 18 point increase in IQ test scores.)

They don't measure the same statistic, but they correlate.

You're selectively citing research on adoption. In fact, there's plenty of research showing that gains are transitory and parental IQ is a better predictor of IQ in late teen years than is the high-SES environment. This whole "mystery" is what prompted folks to ask Jensen to start studying Head Start, as it wasn't clear it was doing any good. The problem is these interventions don't work. They don't work because IQ is genetic.

See Turkheimer: when you withdraw supports like Head Start, you get regression in the short term, but long term outcomes are significantly better, measured by graduation, matriculation into college, &c. That research is from the last 10 years years; Jensen's from the late 1960s. It doesn't help that Arthur Jensen was an out-and-proud white supremacist (sponsored by the Pioneer Fund!), and an associate of swastikas-and-all neo-Nazis.

"That doesn't work because IQ is genetic" doesn't even make sense as a sentence. It implies that something being "genetic" means it's immutable. That's not even how genes work. But it's how people thought they worked in the 1960s, which is where your cite comes from.

I can do the same character assassination on Turkheimer. His own Wikipedia page says he supports the "the radical scientific left" and that his 2003 study that you're probably quoting failed to replicate.

Here's a nice take-down of him that took me 3 minutes of googling to find: https://cremieux.medium.com/is-eric-turkheimer-a-scientist-e...

Oh you don’t get to talk bad about my boy Turkheimer.

I remember my first university assignment when studying psychology back in 2008. It was an essay on the nature vs. nurture debate. I remember going through the sources and deeming the debate kind of stupid. Then I got to Turkheimer, particularly the legendary 2000 article of “Three Laws of Behavior Genetics and What They Mean” which begins with:

> The nature-nurture debate is over. The bottom line is that everything is heritable, an outcome that has taken all sides of the nature-nurture debate by surprise.

And concludes with:

> The gloomy prospect [non-shared environment between siblings accounting for a large part of behavioral variability] looms larger for the genome project than is generally acknowledged. The question is not whether there are correlations to be found between individual genes and complex behavior—of course there are—but instead whether there are domains of genetic causation in which the gloomy prospect does not prevail, allowing the little bits of correlational evidence to cohere into replicable and cumulative genetic models of development. My own prediction is that such domains will prove rare indeed, and that the likelihood of discovering them will be inversely related to the complexity of the behavior under study.

Later in a 2003 study he then goes on and demonstrate that almost all of the variability can be explained by environmental effects (E) and genetic and environmental interaction effects (G × E). None of the previous readings even considered interactions and always concluded with x% E + (100 - x)% G for some x. (EDIT: Catching up my reading I actually see that more recent behavioral geneticists are even using G × E² in their models, that is, the environment also interacts with it self, and that interaction also interacts with you genotype, making for much richer models).

I turned in my paper concluding that obviously there was a flaw in previous studies that don’t look at interactions. Like why is this even being debated any more? I off course got a failing grade for the essay, being of low SES (sorry IQ) my essay skills obviously lacking as I didn’t have the skill (sorry intelligence) to formulate a coherent argument. Thankfully my boy Eric Turkheimer came to the rescue by concluding that actually in a high learning environment like a university in a country which grants equal education to everybody that my skills can be improved (sorry, I mean, my intelligence is malleable), so that I could graduate 3 years later with a first grade.

No, nobody can talk bad about my boy Turkheimer.