
The negative Flynn Effect: A systematic literature review [pdf] - gwern
https://www.gwern.net/docs/iq/2016-dutton.pdf
======
ramblenode
> We did, however, find the average maternal age per country (N = 7) to
> negatively correlate to the level of IQ decline (r = −0.88). Despite the
> small sample size, the correlation reached significance (p < 0.01).
> Nevertheless, as the correlation was negative this seems to indicate that
> among the countries showing a negative Flynn Effect, the ones with the
> highest average maternal age show smaller declines in IQ.

Anyone else see the problem here? They are comparing the change in a variable
over time with the value of another variable at a fixed point in time. That
means they haven't canceled out the time variable, resulting in a confound
with the _change in maternal age_. Would it be possible to get their result--a
negative correlation between greater maternal age at the end of a time period
and a drop in IQ over the whole time period--if, in fact, the correlation
between maternal age and lower IQ is _positive_? Yes.

One way this could happen is if the relationship between maternal age and
lower IQ is linear but the rate of change in maternal age over time is
nonlinear and decreasing. The latter is quite plausible because fertility
already decreases with age in a nonlinear fashion. It's easier for a country's
average maternal age to go from 25 to 35 than from 35 to 45 without even
taking societal factors into account.

The authors admit that their finding is contrary to other research they
reviewed which found maternal age to be positively associated with lower IQs.
My guess is that the discrepancy is because of the authors' flawed model.

Edit: typo, more quote

------
lsd5you
Humanity does not like the lense of science to be turned upon itself and there
will be people who are offended, dismissive or try to hold this academic work
to an impossibly high standard - much higher standard than they would for a
study they find more palatable.

The truth of the matter is that a decrease in the latent genetic 'g' is what
we should expect given a basic understanding of evolution and the structure of
modern society which removes (and reverses) the evolutionary pressure. Of
course 'g' as with any system of caterogisation is problematic, but no more so
than other less contraversial concepts we regularly use. So let's not allow
ourselves be stripped of concepts we need to reason about things - 1984 style.

Evolution is an unfair system, and all attempts to restore (reproductive)
fairness undermine evolution. The obvious compromise is to have fairness in
other matters but not reproduction. For example possibly you shouldn't be
allowed to have many children if you cannot support the first one(s). Of
course others would say the solution genetic engineering (a technological get
out of jail free card), thats another debate entirely (ok, not entirely).

------
rdw
Oh my god, it's literally the thesis from Idiocracy.

~~~
gwern
Makes for some interesting bedtime reading in conjunction with the recent GWAS
studies showing declines in polygenic education/intelligence scores.

~~~
simonsarris
Do you have any recommended links for those recent studies?

~~~
gwern
Sure. Here's a short collection:

\- "Sexual Selection as a Justification for Sex"
[http://www.unz.com/gnxp/sexual-selection-as-a-
justification-...](http://www.unz.com/gnxp/sexual-selection-as-a-
justification-for-sex/)

\- "Holocene selection for variants associated with cognitive ability:
Comparing ancient and modern genomes"
[http://biorxiv.org/content/early/2017/02/20/109678](http://biorxiv.org/content/early/2017/02/20/109678)
, Woodley et al 2017

\- "Rates and Fitness Consequences of New Mutations in Humans"
[http://www.genetics.org/content/190/2/295.full](http://www.genetics.org/content/190/2/295.full)
, Keightley 2012

\- "Parent-of-origin-specific signatures of de novo mutations"
[https://www.gwern.net/docs/genetics/2016-goldmann.pdf](https://www.gwern.net/docs/genetics/2016-goldmann.pdf)
, Goldmann et al 2016

\- "Older fathers' children have lower evolutionary fitness across four
centuries and in four populations"
[http://biorxiv.org/content/early/2016/03/08/042788](http://biorxiv.org/content/early/2016/03/08/042788)
, Arslan et al 2016 (from "The cost of inbreeding in terms of health"
[http://www.unz.com/gnxp/the-cost-of-inbreeding-in-terms-
of-h...](http://www.unz.com/gnxp/the-cost-of-inbreeding-in-terms-of-health/) )

\- "Childhood Autism and Assortative Mating"
[http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.422...](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.422.4232&rep=rep1&type=pdf)
, Golden 2013

\- "Heritability, Autism, & Fear of Breeding"
[http://www.unz.com/gnxp/heritability-autism-fear-of-
breeding...](http://www.unz.com/gnxp/heritability-autism-fear-of-breeding/)

\- "Estimating the Inbreeding Depression on Cognitive Behavior: A Population
Based Study of Child Cohort"
[http://www.plosone.org/article/info:doi/10.1371/journal.pone...](http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109585)
; see also "Genetic diversity and intellectual disability"
[http://blogs.discovermagazine.com/gnxp/2013/07/genetic-
diver...](http://blogs.discovermagazine.com/gnxp/2013/07/genetic-diversity-
and-intellectual-disability/)

\- "Mutation and Human Exceptionalism: Our Future Genetic Load"
[http://www.genetics.org/content/202/3/869](http://www.genetics.org/content/202/3/869)
, Lynch 2016

\- "The Biodemography of Fertility: A Review and Future Research Frontiers"
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4577548/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4577548/)
, Mills & Tropf 2015

\- Fertility and intelligence
[https://en.wikipedia.org/wiki/Fertility_and_intelligence](https://en.wikipedia.org/wiki/Fertility_and_intelligence)

\- "Genetic evidence for natural selection in humans in the contemporary
United States"
[http://biorxiv.org/content/early/2016/05/05/037929](http://biorxiv.org/content/early/2016/05/05/037929)
, Beauchamp 2016

\- "Assortative mating and differential fertility by phenotype and genotype
across the 20th century"
[http://www.pnas.org/content/early/2016/05/25/1523592113.full](http://www.pnas.org/content/early/2016/05/25/1523592113.full)
, Conley et al 2016a (Dysgenics found in the USA, 1920-1955. Appendix
[http://www.pnas.org/content/suppl/2016/05/25/1523592113.DCSu...](http://www.pnas.org/content/suppl/2016/05/25/1523592113.DCSupplemental/pnas.1523592113.sapp.pdf)
); see also "Changing Polygenic Penetrance on Phenotypes in the 20th Century
Among Adults in the US Population"
[http://www.nature.com/articles/srep30348](http://www.nature.com/articles/srep30348)
, Conley et al 2016b

\- in Iceland: decrease in the education polygenic score 1910-1990, "Selection
against variants in the genome associated with educational attainment"
[https://www.gwern.net/docs/genetics/2017-kong.pdf](https://www.gwern.net/docs/genetics/2017-kong.pdf)
, Kong et al 2017 (graph [https://www.gwern.net/images/genetics/2017-kong-
iceland-educ...](https://www.gwern.net/images/genetics/2017-kong-iceland-
education-dysgenics.png) ; media
[https://www.theguardian.com/science/2017/jan/16/natural-
sele...](https://www.theguardian.com/science/2017/jan/16/natural-selection-
making-education-genes-rarer-says-icelandic-study) "Natural selection making
'education genes' rarer, says Icelandic study: Researchers say that while the
effect corresponds to a small drop in IQ per decade, over centuries the impact
could be profound" )

\- in the US: decrease in the education polygenic score 1920-1960, "Mortality
Selection in a Genetic Sample and Implications for Association Studies"
[http://biorxiv.org/content/early/2016/04/21/049635](http://biorxiv.org/content/early/2016/04/21/049635)
, Domingue et al 2016 (graph
[https://www.gwern.net/images/genetics/2016-domingue-usa-
educ...](https://www.gwern.net/images/genetics/2016-domingue-usa-education-
dysgenics.png) )

\- "Genome-wide analysis identifies 12 loci influencing human reproductive
behavior"
[https://www.gwern.net/docs/genetics/correlation/2016-barban....](https://www.gwern.net/docs/genetics/correlation/2016-barban.pdf)
, Barban et al 2016 (supplement
[http://www.nature.com/ng/journal/v48/n12/extref/ng.3698-S2.x...](http://www.nature.com/ng/journal/v48/n12/extref/ng.3698-S2.xls)
; genetic correlations with fewer later offspring: _r~g~_ = -0.236 and 0.712
respectively. Cross-sectional confirmation of Conley et al 2016. )

\- "How cognitive genetic factors influence fertility outcomes: A mediational
SEM analysis"
[http://biorxiv.org/content/early/2016/08/18/070128](http://biorxiv.org/content/early/2016/08/18/070128)
, Woodley et al 2016

\- "The negative Flynn Effect: A systematic literature review"
[https://www.gwern.net/docs/iq/2016-dutton.pdf](https://www.gwern.net/docs/iq/2016-dutton.pdf)
, Dutton et al 2016

\- "Assortative Mating, Class, and Caste"
[https://www.gwern.net/docs/genetics/2015-harpending.pdf](https://www.gwern.net/docs/genetics/2015-harpending.pdf)
, Harpending & Cochran 2015

------
paulpauper
An Iceland study by Kong et al 2017 showed a .1 point decline of a polygenic
measure of IQ, per decade
[http://www.pnas.org/content/114/5/E727.full.pdf](http://www.pnas.org/content/114/5/E727.full.pdf)

This seems small enough that genomic technology in the not-s-distant future
could reverse it

~~~
gwern
They showed a lower bound of .1 points, not a total .1 point decline; the most
reasonable extrapolation would be .3 points, so since the 1910 start of their
sample, -3.21 points (and possibly more since the phenotypic correlations
driving this decline were noted for decades before then in England, but at the
moment, while we have ancient genomes from thousands of years ago and many
modern genomes from 1910AD on from 80yos+, 1000-1900AD is a bit of a doughnut
hole - not so ancient people are willing to sequence without 'consent', but
too ancient to ever get consent).

------
mikeflynn
My name is Mike Flynn and this has been a rough few months to have that
name...and now "The Negative Flynn Effect"? Perfect.

~~~
ssambros
Why don't you just go by Mike instead of Michael? ...

~~~
didgeoridoo
Oh come on downvoters, haven't you seen Office Space?

~~~
0xcde4c3db
I know, don't explain the joke, but for those who haven't seen it (it _did_
come out ~18 years ago, and I'd guess that its popularity/currency peaked ~10
years ago), the relevant scenes:
[https://www.youtube.com/watch?v=_BaMx_n2_hM](https://www.youtube.com/watch?v=_BaMx_n2_hM)

------
dredmorbius
"Richard Lynn is one of the most unapologetic and raw “scientific” racists
operating today, arguing, among other things, that nations with high average
IQs must subjugate or eliminate lower-IQ groups, which he associates with
particular racial groups, in order to preserve their dominance."

[https://www.splcenter.org/fighting-hate/extremist-
files/indi...](https://www.splcenter.org/fighting-hate/extremist-
files/individual/richard-lynn)

I would very strongly advise taking the paper and findings here with an
exceptionally large helping of salt.

~~~
andriesm
How about we just read the paper on its own merits?

More import than related people's political ideology, must surely be the
methodology used, and whether others can confirm the data and methods used as
correct....

Science is not racist or non-racist, it's just science. And the personalities
of the people doing the science should havr no bearing on the correctness of
the conclusions reached if the proper scientific method is used, plus some
peer review and attempts to replicate the findings.

~~~
dredmorbius
Because contexts matter.

Because reputation matters.

Because ideologically-driven "research" often shows both conscious and
unconscious bias. (For a fascinating study of the latter, look up the case of
"Clever Hans".) Forewarned, a closer examination of the piece for flaws is
highly advised. The narrator has proved unreliable in past.

And because it seems of late the practice of giving the benefit of the doubt
seems to have presented itself as problematic in instances.

Yes, it's possible for even the most unreliable of sources to be correct on
occasion. That would be an exception to the rule, and still not provide a
basis for trust, reputation, or authority.

