Cognitive evolution in the past millennium explains much about our current predicament. By Peter Frost.
Europe:
From the Late Middle Ages onward, cognitive evolution was driven by the middle class having more babies than everyone else. They had the skills to identify and exploit opportunities in the expanding market economy, particularly skills like reading, writing, calculating, budgeting, and negotiating. In some countries, most of the population would end up being middle-class or having recent middle-class ancestors.
That baby boom began to run out of steam in the late nineteenth century. Household workshops, where family members did the work, gave way to factories, where it was done by employees. Instead of marrying earlier and having more children, a successful industrialist would hire more laborers. Factory capitalism thus severed the link between economic success and reproductive success.
Meanwhile, the middle-class lifestyle was imposing more and more socially defined needs: a big home, a summer cottage, a luxury car, a college education for the kids, and so on. Couples maintained that lifestyle by reducing the number of children they had.
That fertility decline led to a decline in mean cognitive ability, as shown by several lines of evidence: alleles associated with educational attainment; cranial volume; visual reaction time; vocabulary size; and Piagetian tests.
Decline in alleles associated with educational attainment:
Three studies have shown a decline in the population frequency of alleles associated with high educational attainment, specifically among European Americans, British people, and Icelanders. …
Kong et al. (2017) examined genomic data from Icelanders born between 1910 and 1990 (n=129,808). … The authors found that the mean polygenic score “has been declining at a rate of ~0.010 standard units per decade,” where one unit equals one standard deviation. Moreover, because the polygenic score “only captures a fraction of the overall underlying genetic component the latter could be declining at a rate that is two to three times faster.” …
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. Higher cognitive ability was reducing fertility independently of higher education, perhaps because of its association with the ability to plan ahead and foresee the costs of raising a family.
Lengthening of visual reaction time:
Silverman (2010) obtained visual reaction times from 14 studies published since 1941 and compared them with visual reaction times from a study conducted by Francis Galton in the late nineteenth century. …
Using the correlation between visual reaction time and g, Woodley et al. (2013) calculated a decline of 1.23 IQ points per decade, for a total of 14 points since Victorian times. That decline might be due, however, to a more representative sampling of the general population by later studies …
On the other hand, the same lengthening of reaction time has been shown by Swedish, Scottish, and American participants, particularly those born since circa 1980. The IQ decline was likewise calculated to be 1.3 to 1.7 points per decade …
Reduction of vocabulary:
Twenge et al. (2019) examined the size of the average adult American’s vocabulary, using the General Social Survey of U.S. adults (n=29,912) and controlling for educational attainment. …
Ethnic change does not seem responsible, since non-Hispanic European Americans had almost the same decline: 7.2%
The reduction was mostly in passive vocabulary, i.e., the words we understand but do not use spontaneously in speech. …
Falling scores on Piagetian tests:
A Piagetian test differs from a conventional IQ test in that it is much more demanding. You cannot pass it by simply having a strong procedural memory, low exam anxiety, and good familiarity with likely questions and their correct answers. …
“The Piagetian results are particularly ominous. Looming over all is their message that the pool of those who reach the top level of cognitive performance is being decimated: fewer and fewer people attain the formal level at which they can think in terms of abstractions and develop their capacity for deductive logic and systematic planning.”
And yet IQ scores were rising!
Mean IQ rose throughout the twentieth century. Flynn (1984) calculated a rise of 13.8 points between 1932 and 1978 among European Americans. When that increase, now called the Flynn effect, was charted from 1920 to 2013, it amounted to no less than 35 points …
The Flynn effect began in the core of the Western world and is now ending there. In fact, it has ended altogether in Norway and Sweden and has begun to reverse itself in Denmark and Finland …
The sharp rise in IQ over the past century is far from obvious to someone like myself who lived in that century and who knew people born as early as 1900. I also knew the old textbooks that they used and which our elementary school kept in a storeroom. If they had been less intelligent than my generation, how could they have understood those textbooks? How could they have handled the dense subject matter, the vocabulary, the detailed charts and figures, and the long and complex sentences? …
The Flynn effect also implies that post-millennials are 10 points smarter than my generation. Again, that’s not my impression. Books and movies now have simpler plots and use a smaller vocabulary — a key component of verbal intelligence. …
I suspect we are indeed doing better on IQ tests simply because we’re spending more of our lives sitting in a classroom … and taking tests. In addition, IQ scores may have been inflated by the increase in test preparation during the late twentieth century, notably for the Scholastic Assessment Test (SAT). …
Once the adult population had become fully proficient in test-taking, the Flynn effect ran into a wall and could no longer mask the real decline in cognitive ability. …
Are there steps we can take to reverse that trend? Yes. The first step, and the hardest one, is simply to acknowledge what is happening.
The left cannot even tell the difference between men and women. It barely recognizes the existence of IQ and cognitive differences between people, and certainly not between groups. There is way too much political gain to be had from distorting and ignoring IQ effects, so expect unhindered dumbing down to continue for the foreseeable future.
