Monday, March 16, 2020

From here it's all downhill

Polish IQ scores for three subtests: Similarities, Vocabulary, and Arithmetic (Wikicommons - Pedros)

Throughout the West the Flynn effect is coming to an end. More and more people are bumping up against a ceiling that is getting lower and lower.

The Flynn effect is ending throughout the West. After a century of steady increase, average IQ scores are levelling off and even starting to fall in Scandinavia, England, and Austria (Dutton 2016; Flynn 2007, p. 143; Rindermann 2018, pp. 85-88; Teasdale and Owen 2005). 

But how real was that increase anyway? Read the popular literature from a hundred years ago. Look at the size of the vocabulary and the complexity of the plots. Also look at what people had to know when graduating from elementary school. IQ scores increased during the 20th century largely because people became more familiar with taking standardized tests and thinking in terms of standardized answers to standardized questions. They had no choice. This was a time when people were staying increasingly longer in school. As higher education became the rule for everyone—first high school and then college and university—good grades became the goal for everyone, and not just for a small elite. 

So the average phenotype has been pushed to the limit by compulsory secondary education and by social pressure to pursue tertiary education. Meanwhile, the average genotype has been trending in another direction. 

- Reaction time has lengthened, i.e., people are taking longer on average to process the same information. In Great Britain, mean reaction time has risen by 13 points since the Victorian era (Woodley et al. 2013). This finding may be due to better sampling of the general population over time (hbd*chick 2013); however, a Swedish study found the same lengthening of reaction time, particularly in cohorts born since the 1970s (Madison 2014; Madison et al. 2016). 

- The genetic basis for intelligence has declined, as shown by a progressive decline in the "polygenic score" of alleles associated with educational attainment. In Iceland, this score has fallen since the cohort born in 1910 (Kong et al. 2017). Among Euro Americans, it fell between the 1931 and 1953 birth cohorts (Beauchamp 2016).

In sum, the average phenotype and the average genotype have been moving in opposite directions. This point is made by Hong (2020):

In general, more educated women delay the onset of childbearing and have fewer children overall compared to less educated women. This pattern is very robust in both developed and developing countries, and various theories have been proposed to explicate the intrinsic, potentially causal relationship between education level and fertility.

[...] The phenotype of EA [educational attainment], on the other hand, may experience a very different type of selective pressure. A large literature in sociology shows that educational attainment and socio-economic status are associated, and cultural evolutionary theory predicts that humans readily copy the behaviors of those who are perceived as more prestigious or successful. Although educational attainment cannot be "copied" in a literal sense, individuals who pick models with high EA are likely to be more motivated in learning and committed to their academic studies, and as a result become more likely to obtain higher EA themselves. Thus, genetic fitness and cultural fitness of the same trait (EA) invites selection in opposite directions [...].

As long as the genetic decline is offset by better and longer education, there is nothing to worry about. We may be learning more slowly, but we're spending more time learning. As Courtiol et al. (2016) argue: "the jockey has become more skilled as the power of the horse dwindles."

What if the horse collapses?

Unfortunately, this situation cannot go on forever. The phenotype (“jockey”) and the genotype (“horse”) are not independent entities; in fact, the former is developed within the limits of the latter. As the upper limit gets lower and lower, more and more of us will be bumping up against that ceiling. In other words, "at some point genetics will become the limiting factor in determining the phenotype of EA, which may eventually decline as a result of natural selection" (Hong 2020).

That point seems to be ... about now. In the West, the Flynn effect has exhausted itself, having used up the wiggle room of education. From here it's all downhill.  As Dutton et al. (2016) note in their review of the literature:

Eventually, the ceiling of this ability would be reached and the losses would start to reveal themselves on IQ tests. In addition, Woodley and Fernandes (2016) have shown that the Flynn Effect is not primarily occurring on general and heritable intelligence factor g, whereas the negative Flynn Effect does seem to occur on g. The negative Flynn Effect displays a Jensen Effect, and is mainly occurring on the more heritable abilities.


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.

Courtiol, A., F.C. Tropf, and M.C. Mills. (2016). When genes and environment disagree: Making sense of trends in recent human evolution. Proceedings of the National Academy of Sciences 113(28): 7693-7695.

Dutton, E., D. van der Linden, and R. Lynn. (2016). The negative Flynn Effect: A systematic literature review. Intelligence 59: 163-169.

Flynn, J.R. (2007). What is Intelligence? Beyond the Flynn Effect. Cambridge University Press.

Hbd*chick (2013). A response to a response to two critical commentaries on woodley, te nijenhuis and murphy. May 27

Hong, Z. (2020). Modelling the on-going natural selection of educational attainment in contemporary societies. Journal of Theoretical Biology 493: 110210

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.

Madison, G. (2014). Increasing simple reaction times demonstrate decreasing genetic intelligence in Scotland and Sweden, London Conference on Intelligence. Psychological comments, April 25
#LCI14 Conference proceedings   

Madison, G., M.A. Woodley of Menie, and J. Sänger. (2016). Secular Slowing of Auditory Simple Reaction Time in Sweden (1959-1985). Frontiers in Human Neuroscience, August 18  

Rindermann, H. (2018). Cognitive Capitalism. Human Capital and the Wellbeing of Nations. Cambridge University Press.

Teasdale, T.W., and D.R. Owen. (2005). A long-term rise and recent decline in intelligence test performance: The Flynn Effect in reverse. Personality and Individual Differences 39(4): 837-843.   

Woodley of Menie, M.A., and H.B.F. Fernandes. (2016). Showing their true colours: Possible secular declines and a Jensen effect on colour acuity — More evidence for the weaker variant of Spearman's Other Hypothesis. Personality and Individual Differences 88: 280-284.

Woodley, M.A., J. Nijenhuis, and R. Murphy. (2013). Were the Victorians cleverer than us? The decline in general intelligence estimated from a meta-analysis of the slowing of simple reaction time. Intelligence 41: 843-850.


Anonymous said...

I recommend this book:

A summary of one important point:

That point being is that selection is going in opposite directions for both men and women.

Men are being rewarded for higher IQ but women are not. This selection pressure may eventually exaggerate the sexually divergent IQ between Men and Women

Michel Rouzic said...

It seems that much of the world is overall moving in the same direction, but at least it's good to remember that it can't follow the same direction forever. The dysgenic conditions we're observing are only enabled by a certain level of prosperity and social order made possible by a high average intelligence. When that order and prosperity are gone you should see a return to smarter people surviving better and breeding more than the starving and dying poor.

However looking at the average is only part of the story, the Yule-Simpson effect might be hiding an elite people who are slowly reaching new heights with each generation, I'm thinking for instance of mathematicians or physicists with both parents who excelled in the same field and who despite their low average TFR will probably reproduce that pattern (something that you probably wouldn't see as often before the 20th century), creating generation after generation a small breed of super scientists. So the dumb are ever more numerous, but the smart might be getting smarter? Maybe there's a way to look at the very top range of test scores or contest results that could indicate if that's already happening, independently of the Flynn effect. If it is happening then that changes the picture of what we can expect for the future, instead of everyone becoming uniformly dimmer and worse at such things as scientific research we might see more sophisticated work coming from a shrinking pool of ever brighter scientists. Too bad smart people dismiss both the strict rules of religion and the concept that evolution does anything to modern human cognition, if only they could be smart enough to accept either one, that might help. Too smart to breed, not smart enough to breed anyway.

Anonymous said...

I remember having trouble understanding the vocabulary in The Hobbit at 8 years old, but this kind of book was normal in Tolkiens time.

Excessive vocabulary is not the same as having a good vocabulary, I am sure more people now can recite words and the meaning they have to a greater extant than someone 100 years ago, but it's used in the most banal fashion.

In old letters where words were misspelled, and speech was plain and unsophisticated, there was still effort and expressiveness. Now we use big words loosely and redundantly. (George Orwell lamented this).

The modern education system is less difficult in countries like Finland where school hours are short, breaks are long, and homework is little to non-existant for the reason in the jockey and horse analogy.

Meanwhile in the USA longer and longer hours are continuously forced onto the student body to make everyone catch up, hours of tutoring after school and before for some students. College is for everyone in the USA, while in Europe (and Japan/China?) there are different categories of high schools and vocational/technical schools for anyone who is not an elite.

The irony that a plumber is debt free and making more than the liberal arts degree holder.

Peter Frost said...


There is some debate on this point (which is off-topic, by the way), but most of the evidence I've seen is that men and women don't differ in mean IQ. Men just tend to be more variable in their IQ scores, being overrepresented at the top and the bottom.


I'm not a fatalist, and even a fatalist knows that nothing goes on forever. It's important that we become aware of these trends and discuss. A big problem is the taboo on simply discussing these trends.


Education has become a scam. There is a naïve belief that intensive study will make you smart for life. So we ruin the lives of children by forcing them to cram, cram, cram for silly exams of one sort or another. And for what?

Anonymous said...

@Peter Frost


I hope you review the book.

Sean said...

OT, but I thought you might be interested. "1918 Flu Pandemic That Killed 50 Million Originated in China, Historians Say.

Historian Mark Humphries of Canada's Memorial University of Newfoundland says that newly unearthed records confirm that one of the side stories of the war—the mobilization of 96,000 Chinese laborers to work behind the British and French lines on World War I's Western Front—may have been the source of the pandemic. Langford has shown that China suffered a lower mortality rate from the Spanish flu than other nations did, suggesting some immunity was at large in the population because of earlier exposure to the virus. In the new report, Humphries finds archival evidence that a respiratory illness that struck northern China in November 1917 was identified a year later by Chinese health officials as identical to the Spanish flu.

He also found medical records indicating that more than 3,000 of the 25,000 Chinese Labor Corps workers who were transported across Canada en route to Europe starting in 1917 ended up in medical quarantine, many with flu-like symptoms."

Anonymous said...

Is monogamy in recent history higher in certain societies like in Africa than before with the spread of Christianity and westernization or recent developments by China?

If so will this affect their appearances? I've heard the Igbo have lighter skin, are they more monogamous?

Peter Frost said...


Yes, I suspect China was the point of origin. China has historically had a high degree of "social crowdedness," not only in terms of proximity to other people but also in terms of proximity to domesticated animals of various sorts. Conditions were optimal for viral transmission from animal to human and then among humans.

According to the Wiki article: "A total of about 140,000 Chinese workers served on the Western Front during and after the war. Among them, 100,000 served in the British Chinese Labour Corps. About 40,000 served with the French forces, and hundreds of Chinese students served as translators."

There were another 200,000 Chinese workers in Russia during WW1:


Officially, monogamy has become much more common in sub-Saharan Africa. This is partly because polygyny is costly in urban areas and partly because Christianity forbids it. It's difficult to quantify the extent of polygyny today because so much of it is below the radar of official statistics.

Historically, the Igbo were very polygynous, like most agricultural societies in sub-Saharan Africa:

"Historically, Igbo marriage was polygynous, patrilocal, and involved the payment of bride price. Polygamy was considered the norm for the Igbo—with Ukaegbu (1977) reporting that 34 % of Igbo women in his sample were polygamous—and men commonly aspired to have multiple wives (Basden 1921, p. 97). Colonial-era anthropologists viewed 3 to 5 wives as the most common number for a married man, and the wealthiest and most powerful men could have more than a hundred wives (Basden 1921, p. 99)."

Ardener reported that the Ibgo present a range of skin colors, with the very dark shades being most common, although paler shades are often seen.

Anonymous said...

I suspect this drop in IQ will be more harmful to white countries than what are now the effects of the lower IQ in other countries.

If you take one of these European people and a person from another country, from one of those polygnous societies, of equally lower IQ, the white person usually will not only have a smaller vocabulary, but is a complete and utter twit who cannot express theirself or entertain ideas that exist outside the vocabulary they know (rather than the usual order of a person's limited ideas or culture affecting their vocabulary), nor read the situation.

The other is more likely to have the intact executive function and social ability (sometimes a higher amount of certain kinds social ability), unrelated to measurable intelligence, that allows a person to survive, and in a sense they are more expressive relative to what vocabulary they are limited to.

Language is simplifying, I am not talking about how complicated a grammar is, many languages outside Europe such as Navajo can have terrifying conjugation systems, phonology, and irregular morphology. Rather how COMPLEX it is, how much nuance or depth is expressed. Between Japanese and Korean, the latter is definitely harder to learn as far as rules go, but the former has subtleties not found in the latter.

These will be harsh times.

Santo said...

''Men are being rewarded for higher IQ but women are not. This selection pressure may eventually exaggerate the sexually divergent IQ between Men and Women''

It's not appear to be good, in the long term. Males are often irrational. Inteligence is too precious to be a survived trait and among the least rational (on avg).

Anonymous said...

Does this explain the preference for milder and sweeter foods in the newer generation? Tastebuds are less able to distinguish, so now sweet ciders, sugary cocktails, frappuccinos, flavored tobacco/light cigarettes, and light beers are preferred over unsweetened alcohol or coffee, and plain tobacco. said...

They had no choice. This was a time when people were staying increasingly longer in school