Wednesday, September 14, 2022

The Great Decline

 


Mean polygenic score of Icelanders by year of birth (Kong et al. 2017, Fig. 2)

 

Three polygenic studies have shown that cognitive ability declined among European Americans, British people, and Icelanders during the 20th century. The decline briefly stopped during the postwar baby boom and again with the liberalization of abortion laws.

 

 

How can we measure the genetic component of cognitive ability? For a long time, the only way was to administer an IQ test, but the result would inevitably be influenced by the test-taker’s environment—not only culture and life history but also familiarity with taking tests and answering questions in rapid-fire succession. Yes, twin studies and adoption studies suggest that genetic factors largely explain variation in IQ between individuals. But the same is not necessarily true for variation in IQ between populations. That could be 100% environmental.

 

Recent years have seen the advent of a direct measure of innate cognitive ability: the educational attainment polygenic score. It’s a summation of the predicted effects of genetic variants that together explain 11-13% of the variance in educational attainment among individuals (Lee et al. 2018). It’s especially suited for predicting the mean IQ of a population—the correlation is 98% with the actual mean IQ (Piffer 2019).  Polygenic data predict a mean IQ of about 85 for sub-Saharan Africans, 100 for Europeans, and 105 for East Asians. There is also variation within each of those geographic groups. Among Europeans, predicted IQ varies from 97 for southern Europeans to 102 for Finns and 110 for Ashkenazi Jews. Among sub-Saharan Africans, it seems to be higher among groups who were more advanced during precolonial times, particularly those, like the Igbo, who lived along the Niger and took part in trade between the coast and the interior (Frost 2022).

 

The above predictions should be viewed with some caution. Because the genetic variants have been identified only in people of European descent, the polygenic score is less valid for non-Europeans, particularly those of sub-Saharan African descent. It thus predicts the IQ of African Americans with five times less accuracy than that of European Americans (Lasker et al. 2019).

 

Generational change

 

In addition to predicting differences in mean IQ across space, we can do the same across time. That begs the question: were past generations as intelligent as the latest one? We can answer that question by examining past generations who are still alive. That approach, however, raises the issue of survivorship bias: people who live to an old age are generally smarter than those who do not (Gottfredson and Deary 2004).

 

Beauchamp (2016) deals with this issue point by point when he discusses polygenic data from the Health and Retirement Study (HRS), a longitudinal study of 20,000 Americans shortly before and during retirement:

 

·         The HRS participants are people who have lived to the age of 50; however, about 10% of American women and 15% of American men born in 1940 were already dead by the age of 50.

·         Thus, in Beauchamp’s sample, 85% of the original participants were still alive in 2008, 69% were asked to be genotyped, and 59% consented to be genotyped.

·         Nonetheless, no important differences emerged when he compared the genotyped participants with the total sample. 

 

European Americans

 

Beauchamp found evidence that alleles associated with high educational attainment had declined in frequency among European Americans between the 1931 and 1953 birth cohorts. “[M]y results strongly suggest that genetic variants associated with EA have slowly been selected against among both female and male Americans of European ancestry born between 1931 and 1953.”

 

That decline is attributed to differences in fertility: “individuals with high EA typically have children at a more advanced age, which may further reduce their fitness.”

 

Icelanders

 

The above findings have been replicated by Kong et al. (2017) in their study of Icelanders born since 1910. Although survivorship bias is still a problem, it does not easily explain the decline in cognitive ability between the last two cohorts, i.e., Icelanders born in the 1970s and those born in the 1980s. In that decline, any survivorship bias would be due to deaths of people less than 44 years old, and in most cases less than 36 years old. “The samples studied here were collected between 1998 and 2014, with a majority (68%) ascertained before 2006” (Kong et al, 2017, p. E729).

 

Iceland’s cognitive decline had two “pauses”: one in the 1950s and another in the 1970s. The first pause coincides with the postwar economic boom and a corresponding improvement in the ability of middle class couples to start families early in life. The second pause may reflect the passage in 1975 of Iceland’s abortion law, which, while not allowing abortion on demand, did allow it for cases of rape, mental disability of the mother, and “difficult family situation” (Wikipedia 2022)

 

Kong et al. (2017) concluded that the cognitive decline was due only in part to more intelligent Icelanders staying in school longer and postponing reproduction. In fact, a high educational level, unlike a high polygenic score, was actually associated with somewhat higher fertility among males. A high polygenic score seems to reduce fertility independently of whether one pursues or does not pursue higher education, perhaps because higher intelligence goes hand in hand with greater ability to plan ahead and thus foresee, with trepidation, the costs of raising a family. 

 

British of European descent

 

In a study of British of European origin, using the UK Biobank, Hugh-Jones and Abdellaoui. (2022) found that mean cognitive ability had declined between two successive generations, particularly in lower-income groups. The median birth year was 1950 for the second generation and unknown for the first. The authors also looked at genetic variants that influence non-cognitive traits. In general, the bulk of the population seems to be getting dumber, fatter, and nuttier.

 

The authors nonetheless warn against excessive pessimism:

 

Many people would probably prefer to have high educational attainment, a low risk of ADHD and major depressive disorder, and a low risk of coronary artery disease, but natural selection is pushing against genes associated with these traits. Potentially, this could increase the health burden on modern populations, but that depends on effect sizes.

 

The authors go on to argue that the effect sizes are “small,” although one wonders: smaller than what? They then make the obvious point that generational change can accumulate from one generation to the next: “Although effects on our measured polygenic scores are small even after weighting, individually small disadvantages can cumulate to create larger effects” (Hugh-Jones and Abdellaoui 2022). Beauchamp (2016) makes a similar comment that seems reassuring on first thought, and then not so reassuring on second thought: “natural selection has thus been occurring in that population—albeit at a rate that pales in comparison with the rapid changes that have occurred in recent generations.”

 

Finally, Hugh-Jones and Abdellaoui (2022) point out that their data may suffer from ascertainment bias. For instance, the first generation of their dataset is composed of the parents of the second generation. The dataset thus excludes the childless individuals of the first generation. Were they more intelligent or less intelligent on average than the succeeding generation? Furthermore, participation in the UK Biobank is voluntary. Could that factor also be a source of bias? If so, in what direction?

 

Conclusion

 

As time goes by, intergenerational genetic datasets will become more complete, and the problem of survivorship bias will diminish. Ideally, we should conduct a “genetic census” of each generation, perhaps by collecting a DNA sample from everyone at the time of death. We will thus be able to see how we are evolving.

 

We now have intergenerational polygenic studies from three different Western countries: the U.S., the U.K., and Iceland. In all three cases, the genetic component of cognitive ability declined during the 20th century, with the exception of two pauses: one during the postwar baby boom and the other with the liberalization of access to abortion.

 

If we wish to halt the cognitive decline, we should push for the following measures:

 

·         A return to the protected high-wage economy that prevailed during the postwar era;

·         Free access to abortion, at least for cases of rape, mental disability of either parent, and difficult economic circumstances;

·         Pro-natalist measures to counteract the fear of not having the means to support a family. This fear is particularly strong among people who like to plan and are oriented toward the future.

 

 

References

 

Beauchamp, J.P. (2016). Genetic evidence for natural selection in humans in the contemporary United States. Proceedings of the National Academy of Sciences 113(28): 7774-7779. https://doi.org/10.1073/pnas.1600398113    

 

Frost, P. (2022). Recent cognitive evolution in West Africa: the Niger’s role. Evo and Proud, April 30. https://evoandproud.blogspot.com/2022/04/recent-cognitive-evolution-in-west.html  

 

Gottfredson, L. S., and I.J. Deary. (2004). Intelligence Predicts Health and Longevity, but Why? Current Directions in Psychological Science 13(1): 1–4. https://doi.org/10.1111/j.0963-7214.2004.01301001.x

 

Hugh-Jones, D., and A. Abdellaoui. (2022). Human Capital Mediates Natural Selection in Contemporary Humans. Behavior Genetics. https://doi.org/10.1007/s10519-022-10107-w  

 

Kong, A., M.L. Frigge, G. Thorleifsson, H. Stefansson, A.I. Young, F. Zink, G.A. Jonsdottir, A. Okbay, P. Sulem, G. Masson, D.F. Gudbjartsson, A. Helgason, G. Bjornsdottir, U. Thorsteinsdottir, and K. Stefansson. (2017). Selection against variants in the genome associated with educational attainment. Proceedings of the National Academy of Sciences 114(5): E727-E732. https://doi.org/10.1073/pnas.1612113114   

 

Lasker, J., B.J. Pesta, J.G.R. Fuerst, and E.O.W. Kirkegaard. (2019). Global ancestry and cognitive ability. Psych 1(1). https://doi.org/10.3390/psych1010034    

 

Lee, J. J., Wedow, R., Okbay, A., Kong, E., Maghzian, O., Zacher, et al. (2018). Gene discovery and polygenic prediction from a genome-wide association study of educational attainment in 1.1 million individuals. Nature Genetics 50(8): 1112-1121. https://doi.org/10.1038/s41588-018-0147-3  

 

Piffer, D. (2019). Evidence for Recent Polygenic Selection on Educational Attainment and Intelligence Inferred from Gwas Hits: A Replication of Previous Findings Using Recent Data. Psych 1(1): 55-75. https://www.mdpi.com/2624-8611/1/1/5   

 

Wikipedia (2022). Abortion in Iceland. https://en.wikipedia.org/wiki/Abortion_in_Iceland    

 

33 comments:

jb said...

Do you have a polygenic IQ prediction for the Igbo?

Santocool said...

''perhaps because higher intelligence goes hand in hand with greater ability to plan ahead and thus foresee, with trepidation, the costs of raising a family. ''

Less, when you are high in openness and therefore potentially smarter, qualitatively, than a typical high-IQ normie.

Santocool said...

Most people who intend to vote for Bolsonaro in this upcoming election in Brazil will likely have a higher average IQ than those who intend to vote for Lula.

Because they are disproportionately: white, older, male, middle and upper class, from southeastern Brazil. While Lula's voters are disproportionately: mestizos or blacks, poor,younger and northeasterners.

Bolsonaro is undoubtedly one of the worst presidents in Brazil's quasi-democratic history.

Well, it seems that Dysrationalia is a pretty common problem among people of IQ 100 and above...

Maybe this horde of genotypically intelligent old white people who will vote for a sociopath, were actually more intelligent when they were younger, because...


yeong said...

Not to nitpick but also free access to abortion for health of mother, incest and fetal defect/deformity

Anonymous said...

Santo no one can understand anything youre saying. Please be mindful of readers who want truth and not just incoherency when they read comments etc

Santocool said...

Most people don't want to know the truth. Especially on a blog like this.

Of course, most supposedly intelligent people here know nothing about Brazilian politics, just as they know little or nothing about the politics or culture of any other country than their own??

That, when they really know about their country's politics, without gross distortions by cognitive bias or ideological indoctrination.

What I showed in my second comment is very simple.

The older, whiter, and possibly more genotypically intelligent generation in my country has shown high levels of irrationality in its pattern in elections, not just this one.

This is proof of how limited IQ tests can be, related to qualitative aspects of human intelligence, such as rational ability.

Whether, in collective--comparative terms, groups of higher IQ should be more rational than groups of lower IQ.

This is definitely not what is happening and not just in Brazil, in terms of the pattern of votes in democratic processes.

If only-based on the narrative of this text, people ''who want to know the truth'', can believe that the older generations are, on average, absolutely smarter in Western countries. When, in fact, it is much more complex than just having a larger vocabulary...

Santocool said...

In my first comment, my flaw did not explain that highly intelligent individuals who also score high on openness to experience are less likely to be personally organized, but that this may come with the benefit of making them more intellectualized than normie high IQs.

Anonymous said...

A return to the protected high-wage economy that prevailed during the postwar era...Pro-natalist measures to counteract the fear of not having the means to support a family.

More specifically, it requires measures that discriminate against women relative to men, which is why this is such an intractable problem as feminism and egalitarianism between the sexes have become sacrosanct:

https://cepr.org/voxeu/columns/more-babies-europe-lessons-post-war-baby-boom

"A close inspection of the causes of the post-war baby boom gives little hope for more babies coming to rescue us today. More than anything, the jump in birth rates in the 1950s was fuelled by a stark disparity in the economic opportunities of young men and young women.
Gender inequality helped spur the post-war baby boom

The economic boom of post-war reconstruction delivered fast-growing economies and low unemployment in Europe. In this environment, young men could easily find secure employment enabling them to support a family.

But for young women in the 1950s and early 1960s, labour market opportunities were still largely restricted to traditionally female areas such as secretarial work or retail jobs. Many countries explicitly discriminated against women in the labour market. In parts of Germany, for example, until the 1950s female teachers were required to resign from their jobs once they married.

So, for young women, confronted with a lack of work opportunities – but an abundance of prosperous young men - getting married early and having a large family was a natural choice."

Unknown said...

"No one can understand"

Extraordinary claim.

Anonymous said...

What you said is just a reiteration of the definition of rationality not its links to IQ! See you cant even answer your own questions!

Anonymous said...

If my comments are taken down I will make sure this website gets taken down for threats against my life!

So be careful everyone!

Anonymous said...

Fine Piece of Shit Frost you leave me no choice!

I must take you down along with your blog! You will rue the day!

Peter Frost said...

Hi everyone,

I've been ill for the past few days (and in no position to delete comments). I have deleted the threatening and/or racist comments, but I'm still too weak to reply to the more sensible ones. I'll try tomorrow.

Peter Frost said...

Jb,
For the Igbo? No, that's the first item on my wish list.

Santocool,

White Brazilians vote for Bolsonaro, for the same reason that White Americans vote for Trump: fears about personal security and globalization. I used to know a young Brazilian couple who had emigrated to Quebec City. They weren't rich or "privileged." They said life was becoming too dangerous for everyone in Brazil, unless you were super rich with private security.

Yeong,

Most people would agree with you. Unfortunately, abortion has become a political football.

Anonymous,

Fertility rates declined considerably from the late 19th century to the 1930s. Feminism was, at most, a secondary cause. The main reason was the migration from the country to the city, where conditions for family formation were less favorable. The baby boom was not due primarily to families becoming larger. It was largely due to babies being born to people who, previously, would not have had children. For the most part, these were people of the impoverished middle class. The postwar economic boom gave them the means to have children they otherwise would not have had.

Santocool said...

Frost,

Many white brazilian people vote for someone who want liberalize guns for ordinary people (it will not reduce criminality. Brazil is not Switzerland or Finland: little populations with high avg IQ and relatively normal empathy levels) and that don't care about real issues related with criminality including the heavy proportion of criminal men within brazilian police (militias). It's not just that: global warming/environmental destruction, high living cost & low salaries and social inequality (contributes to criminality).

And Brazil has no problem with immigration yet. Great majority of bolsonaro supporters are significantly ignorant about Brazil socioeconomic issues. Most them are just irrational or stupid. Similar thing happens for trump supporters.

Sorry if your precious white race is mostly composed by irrational people.

Peter Frost said...

Santocool,

The Brazilian couple I met didn't seem "stupid" or "irrational." They didn't claim to have any magic solutions to Brazil's problems. They just said that life was becoming unlivable.

"Chacun a ses raisons." There is always a reason for human action. The reason may seem wrong or illegitimate, but it's still a reason.

Anonymous said...

Peter,

Yes, urbanization and the Great Depression correlated with the decline to the '30s, although I don't see why that would be inconsistent. The Depression resulted in large numbers of men being unemployed/underemployed for a long time, lowering their relative economic status considerably.

As for the baby boom consisting of more widespread fertility and family formation, isn't that relevant to our discussion? I presume we're talking about synthesizing fertility in the context of a social norm of relatively widespread life long monogamy and family formation. Obviously you could have a scenario in which polygyny was dominant and have high fertility while the economic conditions and prospects for most men were poor. But we're assuming a social norm of relatively widespread life long monogamy and family formation, no?

If we aren't assuming that, then it'd be true that sexual egalitarianism in the non-domestic economic, professional, and public sphere would be less relevant. Greater economic independence and status for women and consequent lower economic status for men in general would matter less for fertility if polygyny were a norm and more women could get impregnated by a minority of higher status men.

The issue to me seems that we have a long legacy of lifelong monogamy based on female dependence on male breadwinners, and that this has been disrupted in a relatively short time by women becoming as economically independent as men, making the modal man much less desirable and acceptable as a spouse. There is data suggesting women now do better than men in higher and professional education and in the workforce. And about 1 in 7 men in prime working age 25 to 54 in America are not working today. The most upper ranks of high status jobs and positions in society and levels of wealth are still dominated by men, but the average man has certainly seen a significant relative decline over the past few generations.

Women with a certain level of educational, professional, class, income status generally use their economic independence and younger fertile years these days seeking men who are at a minimum of the same rough level as themselves and preferably higher as potential spouses and mates. The pool of marriageable men is simply much smaller today.

The simple material economic explanation is not sufficient. Orthodox Jews and the Amish for example don't have a material economic advantage over ordinary secular men today. What the men in those communities still have today is greater relative social status within their culture.

Santocool said...

''Santocool,

The Brazilian couple I met didn't seem "stupid" or "irrational." They didn't claim to have any magic solutions to Brazil's problems. They just said that life was becoming unlivable.

"Chacun a ses raisons." There is always a reason for human action. The reason may seem wrong or illegitimate, but it's still a reason.''


Dear Peter,

If it were, I wouldn't analyze a country's socioeconomic situation based on just one report...

I didn't say the couple you're talking to is irrational or their reasons.

Is arming a population a magic solution for you?


Dear Peter,

The word ''reason'', both in your language and in mine, has more than one meaning.

And honestly, whenever someone uses a phrase in French, I get a little suspicious, because France is a pathetic country, land of ''modern philosophy'', which is mostly-pathetic.

Santocool said...

...but I would not doubt if this couple were not also predominantly irrational, if this has been the human rule, the only species that can be rational and therefore irrational.

Peter Frost said...

Anon,

Actually, most of the fertility decline took place before the Great Depression. I would give the reasons for that decline as follows:

- migration to the cities, where children are not needed for farm labor
- fragmentation of inter-generational ties. People were less certain that their children and grandchildren would support them in their old age.
- beginnings of "youth culture," glorification of singlehood in movies and popular literature.
- weakening of social pressure from religion and community

"The pool of marriageable men is simply much smaller today" Bullshit. I personally know several single men who have good jobs and own their homes, and they can't find women who are interested in marriage, other than single mothers.

I agree with your point that women are more financially independent, and one consequence is that women are taking longer to commit (and they often commit to men who are high on "personality" and low on financial stability). We are seeing the same phenomenon in East Asia, where feminism is much less present.

In sum, I agree with much of what you say. Unfortunately, you also tend to repeat a lot of dubious talking points from the manosphere.

September 24, 2022 at 2:09:00 PM EDT

Anonymous said...

Bullshit. I personally know several single men who have good jobs and own their homes, and they can't find women who are interested in marriage, other than single mothers.

By "marriageable men", I mean something conditioned by the subjective preferences of women, not simply objective measures. I agree that by objective measures, there are many single men who have good jobs, incomes, property. But this is less desirable in the subjective preferences of women when they can support themselves economically, have access to jobs, careers themselves, etc.

I agree with your point that women are more financially independent, and one consequence is that women are taking longer to commit (and they often commit to men who are high on "personality" and low on financial stability). We are seeing the same phenomenon in East Asia, where feminism is much less present.

"Feminism" has a lot of ideological baggage and lots of various connotations. It probably wasn't the best idea to introduce the term in this discussion.

In sum, I agree with much of what you say. Unfortunately, you also tend to repeat a lot of dubious talking points from the manosphere.

I don't consider myself part of the manosphere and I don't really see them discuss these details and issues in depth.

reading said...

Wow. A decline 0.15 SD, two whole IQ points. Less than the standard error on the population averages.

Peter Frost said...

"A decline 0.15 SD, two whole IQ points."

Interesting, if true. But the chart seems to say otherwise. Please enlighten me.

Peter Frost said...

"By "marriageable men", I mean something conditioned by the subjective preferences of women"

That distinction is important. I sometimes hear women complain about the lack of marriageable men, but they're like employers who complain about "jobs going begging" or "vegetables rotting in the fields." Sometimes, people have unrealistic expectations, and this is true for both men and women.

Anonymous said...

I think the feminist ideology is responsible for a greater masculinization of roles for women that they are encouraged and pushed into. Negatively impacting fertility.

Especially for more brighter women. On the other hand wealthy men have far less issue reproducing.

Pumpkin Person said...


"Interesting, if true. But the chart seems to say otherwise. Please enlighten me."

The chart says polygenic scores were about +0.10 SD circa 1915 and about -0.05 circa 1985. That's a decrease of only 0.15 SD or 2 IQ points. Is that even statistically significant given the sample sizes?

Anonymous said...

whoa Pumpkin featuring Peter Frost would be an excellent rap video. you know who this is PP.

Pumpkin Person said...

you know who this is PP

My guess is Loaded

Anonymous said...

Good guess

Peter Frost said...

Pumpkin,

The y axis is average polygenic score. For each decade, the SD of the PGS is plus or minus 0.01 (approximately). So your calculations are off by a factor of 10, even if one accepts your premises.

There are ways to convert PGS into IQ. Davide Piffer might help you.

Santocool said...

My last shoot for this shitty blog

https://the-big-ger-picture.blogspot.com/2019/09/the-psychology-and-biology-of-gifted.html?m=1

I have intellectual monotony... really

Santocool said...

I HAAATE not have

Grrrrr

Pumpkin Person said...

Peter, thanks for the reply. Seems odd the SDs would be so small (maybe you're thinking of the standard error?). Anyway, I'll try to reach out to Piffer.