
IQ scores are falling and have been for decades, new study finds - lastofus
https://www.cnn.com/2018/06/13/health/falling-iq-scores-study-intl/index.html
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ve55
It takes a lot more than one paper and a CNN article to overturn the evidence
that is against this. I'm not talking about IQ scores falling, but rather the
cause of it suggested here. Although the environment does have notable roles
(for example the impact of lead), it's naive to come out and say that the
environment is all that matters in driving these effects. Dysgenic Fertility
([https://en.wikipedia.org/wiki/Dysgenics#Fertility_and_intell...](https://en.wikipedia.org/wiki/Dysgenics#Fertility_and_intelligence))
is different in different countries, and the pattern of change mentioned in
the article is also different, with Norway often being a bit of an outlier.

>It's not that dumb people are having more kids than smart people, to put it
crudely. It's something to do with the environment

This is false. The correlation between cognitive ability and number of
offspring is negative. Here's a link to a systematic review on this topic:
[http://sci-hub.tw/https://www.sciencedirect.com/science/arti...](http://sci-
hub.tw/https://www.sciencedirect.com/science/article/pii/S0191886918302903)
that covers many datasets, where you can see the negative correlations on page
114 (8 in this pdf), which vary from -0.01 to -0.27 depending on the group in
question. Although this does not rule out an environmental influence by
itself, it's dishonest to simply dismiss it as the article has done.

> In a separate study that has not been released, he and his colleagues looked
> at existing research in an effort to demonstrate that staying in school
> longer directly equates to higher IQ scores. Keyword here is "an effort to
> demonstrate". That sounds like they really want the results to come out in
> their favor, and we know that is not a good sign. They can mess around with
> correlation and causation and p-values and subgroups and framing all they
> want, but whatever they come up with will contradict a lot of the existing
> literature in this area in order to push their agenda.

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jarfil
The simplest explanation would be that either the IQ tests are missing some
aspect of human cognition that is getting more developed in spite of others,
or that the weighting used to calculate the final IQ number based on the
particular results might be wrong or not representative of the actual
cognitive effort required for each of them.

Let's not forget that IQ tests are just statistical analyses, while we still
lack a bottom-up explanation of intelligence.

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TangoTrotFox
This is not a new discovery. It's known as the Flynn effect. [1] It initially
was the observation that IQ scores were constantly increasing over time. This
was one of big correlations in support of intelligence being driven by
environment. Our environmental conditions were improving, and so was our IQ.

But then sometime starting around the mid 90s it began to reverse in developed
nations. And by reverse, I mean IQ's began declining - not approaching some
sort of asymptotic 0 level of growth. So, if we normalize for age, an average
person born in the 70s will have a higher IQ than an average person born in
the 90s.

[1] -
[https://en.wikipedia.org/wiki/Flynn_effect](https://en.wikipedia.org/wiki/Flynn_effect)

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jl2718
I have no PNAS*, but just for starters...

Firstly, this is such a massive and important finding, even cessation of the
Flynn effect would be, that one has to wonder why we haven’t seen it published
until now.

Secondly, one of the frustrating parts of being a statistician is that a 90%
explanation of nearly every effect comes from some common-sense factor. So
much so that it raises suspicions when a strong effect is shown along with a
series of specific and fairly complicated ‘anti-explanations’. The article
seems more interested in disproving the ‘idiocracy’ effect than finding some
alternative explanation.

~~~
cadencia
PNAS? I've never seen this short form before. What does it mean?

~~~
bribroder
(he means a subscription with [http://www.pnas.org/](http://www.pnas.org/))

~~~
cadencia
ahh, thank you!

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devnull791101
Literally for decades people have been predicting average IQ scores would drop
due to social/genetic factors. It's evidence of a successful theory. Society
should stop pandering to the lowest common denominator and allow gifted
students to excel in separate environments

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mhkl
A few days ago naturalness.com had an article about this topic and refers to 3
scientific studies that show that the more toxins the mother was exposed to,
the less IQ the child has. It is a linear function.

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pwinnski
Dupe of
[https://news.ycombinator.com/item?id=17302830](https://news.ycombinator.com/item?id=17302830)

