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Comment by Pepe1vo | Hacker News Reader

This study seems to base its conclusions for the most part on a study from 2016[0] and a study limited to Norway[1]. Both of these studies base their findings on data from 1995-2005 (with the exception of the Netherlands and Britain which both span larger periods) this data itself is collected from variety of experiments with varying sample size and testing methodologies.

There certainly appears to be something interesting here, but I'd be hesitant to draw any conclusions from this data the way TFA does, which reeks a bit of sensationalism. At best I'd call it something worth investigating more thoroughly, at worst it's statistical noise.

[0] https://www.gwern.net/docs/iq/2016-dutton.pdf

[1] http://differentialclub.wdfiles.com/local--files/assigned-to...

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This is the kind of study where I expect in a few months to see headlines about IQ NOT dropping, and then more headlines about how IQ is dropping and in the end the whole thing is inconclusive.

The more attention grabbing the headline is the more skeptical I am of the study.

Hasn't it only "fallen" by something like 1 point? That seems like it may easily be due to some (potentially very hard to identify) confounder.

If it fell 1 point per 10 years, but used to grow 3 points, that is a much stronger change than the bare number suggests. (My numbers are made up and unsourced)

>Substantial gains in GA were apparent from the mid 1950s (test years) to the end 1960s–early 1970s, followed by a decreasing gain rate and a complete stop from the mid 1990s. [...] It is concluded that the Flynn effect may have come to an end in Norway.

The single and/or the first children have higher IQ, so the Flynn effect is a reverse to the number of children per family, ie. it is a reverse to that graph:

https://data.worldbank.org/indicator/SP.DYN.TFRT.IN?location...

And on the other side of the world - the "one child” policy results are in:

"An increase of intelligence in China 1986–2012" https://www.sciencedirect.com/science/article/pii/S016028961...

https://data.worldbank.org/indicator/SP.DYN.TFRT.IN?location...

I wish that I saw more of these comments on HN links to science articles that explain some research paper. From now on, every such comment that analyzes the underlying study's power and significance, I'm going to upvote, as a general policy.

If it is in fact happening, perhaps carbon dioxide levels during pregnancy and early brain development are critical?

We know that elevated CO2 is negatively correlated with cognitive scores: https://www.yaleclimateconnections.org/2016/07/indoor-co2-du...

From your link:

>"But a new Danish study failed to confirm these findings. The paper, published in February 2016 in the journal Building and Environment, reports no cognitive decline even when subjects breathed air containing 5,000 ppm carbon dioxide."

>"Even scientists who have found an effect say more research is needed before they are convinced that modest amounts of carbon dioxide are a public health problem. Satish says that, so far, nobody even knows by what biological mechanism carbon dioxide might dim the brains of test subjects."

I feel like people are way too readily accepting this CO2 cognitive decline thing. There are other comments here saying that we know CO2 causes cognitive decline.

So it's reversion to mean which is often seen in nature. If we see that today we don't really need high IQ to navigate our way through the cities, nation or even continent because we've GPS and other technologies which drastically reduce the amount of complexity we need to keep up with. Why should a higher IQ exist then?

If we look at the past and see when and where the IQ increase took place, we see it increasing when when we were required to complex terrain and protect ourselves from harsh climate.

i see 'outrage culture' being a big part. instead of thinking and talking, it's easier to just say 'bigot-racist-homophobe'.

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