Interesting article. To what extent do you think increasingly cognitively complex western societies have kept their populations reasonably sharp, despite a decline in innate ability? IOW, are IQ scores reasonably accurate measures of these societies’ cognitive performance despite their lowered capacity?
I'm not sure what you mean by "sharp." We've compensated for the decline in cognitive ability through labor specialization, improvements in finding relevant information (via the Internet) and, recently, use of AI. I find it much easier to research an article today than I did twenty years ago.
If, by "sharp," you mean mental acuity, I would say we have less of it today than fifty years ago.
Excellent. A very good pulling together of disparate strands. Thank you.
My impression is that Maths scores never increased, nor did Digit Span (though the easier digits forwards may have creeped up a bit, and the harder digits backwards fallen back).
Yes, that's my impression as well. The shorter and simpler the test, the less we see the Flynn effect.
At school and university, I did better on term papers than on tests. I remember having nightmares long afterwards, in which I would be faced with an insoluble problem or a labyrinth with no exit.
Your comment "In the late nineteenth century, this trajectory began to stall and go into reverse" is interesting. I have no basis to comment on the IQ trajectory (either in agreement or disagreement with your thesis) but I have written - on my own Substack and elsewhere - about another 19th/20th trajectory; one that has had huge significance for our current Western societal discontents. I am talking of a syndrome whereby the offspring of the early muck and brass entrepreneurs tended to not follow in their fathers' hard-nosed footsteps but rather came instead to aspire to be more socially 'sophisticated'….. the beginnings of a nascent Left-leaning (and malcontent) intelligentsia. This is a huge and complex subject, way too big to do justice to in a comment thread but it is a subject, as I say, that I have explored as a major theme of STB.
It's my perception, admittedly mostly based in my gut, that western culture has gradually legitimized self-absorption under the more acceptable term "introspection". This has increased mostly among the middle class, and had previously been tolerated and even expected for females, but this toleration has been extended to males, as well.
In a sense it's a part of the feminization of western culture, for better or for worse.
But one of the side-effects is that it narrows both the scope of one's mental activity to the familiar--one's own preferences, habits, values--while concurrently reducing the amount of time in absolute terms spent on problem-solving external situations that may come one's way. The net effect is to spend a greater portion of one's mental energy plowing and re-plowing the same mental field, without breaking new ground on which to refine one's mental acuity; in essence, it is practice rather than learning--and one does not grow much from practice
I don't know for sure if this actually is in play or not, or even if it has the effect of gradually "dumbing down" those who practice this increased self-absorption.
Thanks for the pointer. I have not read it but have come across references to it down the years and so am aware of its standing. Re his identification of the artist as the primary antinomian cultural force, I have recently had what are for me some uncharacteristically optimistic thoughts....That - given our culture's currently hegemonic decadent progressivism - the most trenchant challenges to its orthodoxies might just possibly eventually emerge more from artist rebels than from dissident politicos. (Not holding my breath though.) I explored this theme here: https://grahamcunningham.substack.com/p/art-will-keep-us-alive
Lead exposure could be a confounding factor. One study estimates that US lead pollution is responsible for an average IQ loss of 2.6 points per person as of 2015.
For some measures perhaps. Lead exposure wouldn't explain the decline in alleles associated with high educational attainment. As the other commenters point out, lead exposure seems to be declining.
Yes, that is true, but as the study points out, at one point, the "average blood–lead level (BLL) for the general US population was routinely three to five times higher than the current reference value for clinical concern and case management referral."
The average person is apt to grossly underestimate the tremendous impact of lead exposure on society. Consider how many people it has killed outright:
"The population attributable fraction of the concentration of lead in blood for all-cause mortality was 18·0% (95% CI 10·9–26·1), which is equivalent to 412 000 deaths annually."
I agree with you about the allelles being a factor but I should suggest that more highly-strung (and therefore higher-IQ) people could be prone to succumbing to the toxicity first.
Yes, the limited data we have suggests that brain size has increased much like IQ scores have increased, though that brain-size data may not be reliable. A more reliable trend, in my opinion, is the increase in intracranial volume over the 20th century (Jantz & Jantz, 2016), which confirms the brain size trend data. That skull-size trend is well-validated, so it is odd to me how researchers of the Flynn effect seem unaware of it.
And it is not just that but many other covariates of actual intelligence have trended over the 20th century in the direction of actual rising intelligence, including those biological traits such as increasing height, increasing adult longevity, decreasing fertility, increasing birth weight, and decreasing child mortality. Not every component of general intelligence would be expected to rise: reaction time and color acuity have either remained the same or fallen (the decrease in vocabulary knowledge seems to be merely an expected shift in language; the current generations have less knowledge of The Beatles and The Rolling Stones, but that does not tell you much). But, most components of g have indeed risen. So, with exceptions, generally both the biological stuff and the social stuff has trended in the direction of increasing intelligence.
So why do we resist the easy inference that intelligence itself has risen? Maybe because it is so highly heritable? Adult height is even more strongly heritable (h^2=90%), and in some populations it has risen by more than two standard deviations (NCD-RisC, 2016). Human DNA hasn't changed enough to explain that change over the 20th century, but it is not even mathematically possible to explain the trend with the 10% environmental remainder. We will need to start taking seriously the possibility of changes in genetic expressions, that being the infamous E word: epigenetics. It allows for the possibility that environmental effects can be heritable. We have not isolated the molecular mechanisms for it, but it is likewise the only possible reason why the phase state between solitary grasshoppers and gregarious locusts is likewise heritable. We simply have no other means to explain it.
The study by Jantz and Jantz (2016) shows an increase in mean American cranial size from c. 1820 to c. 1920, followed by no further improvement (there is no cranial data before 1820). That increase is actually before the time range of the Flynn effect.
I believe that Jantz and Jantz (2016) captured the tail end of an upswing in cognitive evolution that began perhaps in Late Antiquity or the Middle Ages and ended shortly after Victorian times. For the reasons why this increase in cranial size was not a "rebound" due to improvements in nutrition, please read my post at: https://evoandproud.blogspot.com/2019/07/why-did-brain-size-decrease-after-ice.html
I have trouble understanding the argument in your second paragraph. And that means I don't follow your third paragraph either.
If mean intelligence had risen over the 20th century, we would see this rise in the culture. Do you believe that modern culture has become more cognitively demanding? Is recreation more cognitively demanding today than it was in the past? At best, the evidence on this point is weak.
Nor am I convinced, for instance, that adult longevity is a measure of mean intelligence. Or decreasing fertility. In any case, adult longevity has been declining in the US.
Thank you for your consideration here. I love drawing attention to the trend of increasing skull size. You may have misread Jantz and Jantz (2016). To quote from the abstract: "Samples were organized into 10-year birth cohorts, with birth years ranging from 1820 to 1990." Not 1920. Their observed trend of increasing skull size covers the full scope of the Industrial Revolution until the current generation. And the 19th century is not the tail end of an upswing, but it was when there was a stall, and the upswing was in the 20th century.
I will put aside the other points I made for now. Thank you.
No, I didn't misread Jantz and Jantz (2016). May I quote from that paper? "[Cranial
size/capacity] exhibits a nadir in the late nineteenth century and recovery until about 1930, much like the cranial module." If you look at Figure 2 (p. 59), you will see that cranial size stops increasing circa 1920.
I wish I could cut and paste that figure into this reply. Unfortunately, that doesn't seem possible.
Peter Frost, no worries, I have the full text, and I have studied it. I agree with you partially in that the trend of cranial module is ambiguous in isolation. I preferred a simple linear trend in which the slope would be positive, but you may prefer a higher order fit that would infer a stall at 1920. Simpler fits are generally better, in my opinion, but we not settle on that particular principle to make full sense of it. The study is not just about size but also shape, and the shape trends are much more definitive.
I invite you to look at Figure 1, which clarifies what is really going on, because it is not just the total size but it is more specifically many dimensions that are trending in much more clearly linear directions (though conflicting with respect to size). For BBH (height), BNL (length) and XCB (breadth), the inflection point is at about 1880 for all three trends, proceeding linearly thereafter with no change in slope at 1920 for any of those three dimensions, for both males and females. It means, since the 1880 birth cohorts, our heads have been getting taller, longer, and narrower. A similarly increasing linear fit for cranial module would therefore match those three related trends best.
I looked at this study years ago, but an additional thought just now occurred to me: this set of specific shape trends may be more relevant for the total point of increasing intelligence. Greater length and height at the expense of width would accommodate a greater size of the frontal lobe, the primary seat of general intelligence, at the expense of other brain regions.
I am happy to read your additional thoughts on the matter, regardless of our disagreement.
In other words, White Americans have become longer-headed over the past two centuries. This trend might reflect immigration from southern Europe, or it might be due to improvements in nutrition. I don't know. Anyway, there is no good evidence that long-headed humans are more intelligent than broad-headed humans.
In addition, the cranial data is taken from the Forensic Anthropology Data Bank, which suffers from the same bias I noted in autopsy studies. Initially, the skulls were from condemned criminals or unidentified victims. Other human remains would be given a Christian burial. During the 20th century, cranial data became more representative of the general population. That bias would inevitably create a false impression of increasing brain size.
"...never been so stupid." I think the elitists of every generation believe they are smarter than the younger folk. But, the total numbers really do tell the opposite story. It is not just increasing IQ scores. It is increasing scores of academic standardized tests, increasing educational achievement, increasing enrollment in calculus courses, and increasing GDP per capita. Like I mentioned, it is also increasing skull size. Like Peter Frost mentioned, it is also increasing brain size; he discounted it, but it accords with increasing skull size and increasing IQ etc. To justify our elderly elitist prejudice that kids today are stupider, we need to cherry pick the trends in favor of decreasing Intelligence. But the big picture really is in the direction of increasing intelligence over the 20th century.
"I think the elitists of every generation believe they are smarter than the younger folk."
You should use the terms 'older generation' and 'wiser'. The older generations are wiser than the younger generations.
"It is not just increasing IQ scores. It is increasing scores of academic standardized tests, increasing educational achievement, increasing enrollment in calculus courses, and increasing GDP per capita."
You failed to mention that tests have been dumbed down, and the number of college students has risen inordinately due to lowered acceptance requirements. The U.S. GDP has lost its meaning because it includes financial products rather than productive output. The distribution of wealth in this country is criminal, and intelligence has very little to do with it, but rapaciousness does.
I do stand by my assertion that this country has never been stupider, and I do not level than on just the young. One only has to be aware of what is happening, on a minimal level, in this country to see that stupidity rules.
Yes, within every generation, the older generation is wiser (I prefer the word "smarter" to denote the objectively measurable raw computing power of the brain) and the next generation is stupider. Every generation would agree with thy movie Idiocracy. But, I am all about the numbers, and the dysgenic theorists need to cherry pick the numbers to prove their point. I will provide further relevant examples: both literacy and numeracy have trended upward all over the world over the twentieth century, if it hasn't already reached a maximum at about 100%. If we are getting stupider, then we generally expect downward trends among countries, but they don't exist. You can dismiss each of all the otherwise-converging data points, but the consilience of the total body of evidence no less stands in favor of a drastically-increasing intelligence trend. The evidence could have stopped at the increasing IQ, and no need to go beyond that. But we also have a large pile of covariates trending in the same direction compared to triflingly few going in the opposite direction.
"the pool of those who reach the top level of cognitive performance is being decimated.." except in China, where it is already freakishly high and still rising.
We have very limited data from China. The Flynn effect seems to be ongoing in that country, but we have no reason to believe that this increase is a real increase in cognitive ability.
The Flynn effect may be ongoing but the nutrition/education/urbanization trend certainly is. Current IQ is 106, heading towards first tier cities' 108.
There have been only four studies on the Flynn effect in China, and three of them are based on small samples. Qi and Xiong (2023) found a Flynn effect among Chinese adults born between 1935 and 1984. However, a lot happened in China between those two years, and it's impossible to tell whether this was a real increase in intelligence or simply an increase in familiarity with test-taking.
Also, there has been no study of generational changes in alleles associated with educational attainment. The evidence I've seen is that fertility has been lower among Han than among non-Han, and lower in the cities than in rural areas.
I agree that cognitive ability is high among the Chinese, but I see no evidence that their mean cognitive ability is rising. If anything, it should be falling, since the best and the brightest tend to go to the big cities, where they end up having no children.
Qi, Y., & Xiong, Y. (2023). Intercohort upsurge of cognitive ability among the general population in China: Evaluating a Flynn effect. Intelligence, 98, 101752. https://doi.org/10.1016/j.intell.2023.101752
The sad part for the United States is its intransigence on IVF embryo selection and genetic enhancement of positive human traits. This attitude will lead to an even larger cognitive performance differential between the two.
Embryo selection for cognitive ability is not realistic at this time (PGS Edu has low predictability for individuals).
On the other hand, I am in favor of assisted reproduction (IVF and surrogacy) because it increases the fertility of those couples who are above-average not only for cognitive ability but also for time preference and other desirable traits.
> When I look through her books, I’m struck by the differences between them and the ones published today, not only in font size but also in vocabulary, sentence length and sentence complexity.
I broadly agree with Peter Frost's argument here, but this is a very bad argument that needs to be retired from Flynn Effect discussions with prejudice.
Good writing is crisp and concise. It uses simple words where such suffice. Sentences are short, not meandering and convoluted for their own sake.
On average, today's writing is much better than it was a century ago, at least as judged by commonly accepted rules of what constitutes good writing.
Yup. Similarly, various people love to say that Raven's Progressive Matrices is a culture-free assessment of intelligence, but (by my accounting) it is probably the most culture-dependent. Answering a certain type of pattern-recognition question is very much a "Western education" trained skill.
Actually, standardized testing was introduced into Western education at a very late date. In the late 19th century, it was still condemned as a Chinese idea and was not widely introduced into the school system until the early 20th century:
"When the report was brought up in parliament in 1853, Lord Monteagle argued against the implementation of open examinations because it was a Chinese system and China was not an "enlightened country." Lord Stanley called the examinations the "Chinese Principle." The Earl of Granville did not deny this but argued in favor of the examination system, considering that the minority Manchus had been able to rule China with it for over 200 years. In 1854, Edwin Chadwick reported that some noblemen did not agree with the measures introduced because they were Chinese. The examination system was finally implemented in the British Indian Civil Service in 1855, prior to which admission into the civil service was purely a matter of patronage, and in England in 1870. Even as late as ten years after the competitive examination plan was passed, people still attacked it as an "adopted Chinese culture."
"Culture is a product of intelligence. It is the portion of our environment that we design and create through mental effort."
If people's actions are indicative of intelligence, using the United States as an example, intelligence is dropping precipitously. Stupid is as stupid does. Way too many people in this country are stupid on a stick.
"Intelligence researcher Robert Howard (1999, 2001, 2005) cites four pieces of evidence for a real increase in intelligence:
A decrease in the prevalence of mild mental retardation
An increase in the number of chess players reaching top performance at earlier ages
An increase in the number of journal articles and patents each year
An increase in the practical ability of schoolchildren, albeit without a corresponding increase in average general intelligence, in ability to do school work, and in literacy skills (according to a survey of high school teachers who have taught for over 20 years)."
The author is too kind to Mr. Howard, describing the data as debatable. It is fraught with misinterpretation of data and disregard for obvious explanations for the apparent increase in intelligence other than an actual increase in cognitive ability.
Yes, this is my gut reaction. I lived through the late 20th century and knew many ordinary people from the early and mid-20th century. They read books like we now watch cable TV. Many novels of that time were initially published as instalments in popular newspapers.
I agree that it doesn't have much to do with actual intelligence. All this is just testing for deliberate practice and hyperspecializing in a particular skillset.
The reason this happens is because we put a lot of systems in place that greatly reward this behavior, in fact my opinion is that it disproportionately rewards this type of endeavor that is mostly pointless in the grand scheme of things.
At the end of the day, you quickly figure out that there is not a particular strong correlation between the best at a particular activity (taking school test being one of them) and actual "practical intelligence"; sometime they do go together but it is hardly guaranteed.
The decrease in mild mental retardation could be muh easier attributed to better environmental factor (better nutrition, medicine, instruction, etc) and the tail end of genetic selection, because as women become wiser and freer, less opportunities to make a child was given to extreme genetic outlier in the intelligence department (the corollary is that it also prevails for the other extreme, data seems to confirm that as well).
I don't understand the fetish people have for chess. If you take 2 completely noob players, the superior intelligence will probably win but at a very high level it doesn't have that much to do with proper intelligence. It is a lot of rote memorization and psychological warfare in many ways. There is just not enough time to properly calculate all the possible moves (even at end game) for logic/intelligence to be that significant of a factor, it can't hurt for sure but it's doubtful that it can be a significant marker of intelligence. Just in general I believe intelligent people tend not to like games that much because at the end of the day it ends up being mostly a pointless competition that doesn't add much to one's life or any other for that matter.
For school things, I'm inclined to believe the data but it has a lot more to do with environmental factors than actual intelligence. Turns out that being literate much earlier and being subjected to all kind of mental stimulation ensure a decent floor of intellectual competency; that would be sad if it wasn't the case considering that is the whole point of public school and they didn't achieve these results for all that they cost, that would be a rather pointless waste of ressource.
Culture is indeed a reflection of the intelligence of its stewards and I agree that it is most likely dropping not just in the US but in general in the western world.
I believe it has become fashionable to shit/hate on intelligent people, mock them and decry their efforts which is why there are fewer and fewer truly intelligent people who take part in the public discourse to shape the culture.
Social media also has given too much voice to a majority of idiots who effortlessly overwhelm any kind of effort to establish a higher level of discourse by more intelligent people.
The Greek philosophers had already warned about this in their writing, in that true democracy is not actually desirable because while everybody will have an opinion and things to say about anything they cannot be given the same value depending on who is actually emitting the opinion.
Social media and modern politics give the opportunity for even the worse specimens of humans to give their opinion and influence the trajectory of culture and things alike. For obvious statistical reasons they outnumber the more desirable part and other times it will inexorably regress to a less optimum mean.
People seem to be confused about all this but even if you are an optimist, when you push things to their logical conclusion this is the "best solution" you can find.
I believe that across the ages, the boom and busts of different civilization/society is very likely to be linked to such factor, the better the society is doing, the more inclusive it is of "lesser" people but the more it led it to its natural ending, logicaly...
"The decrease in mild mental retardation could be muh easier attributed to better environmental factor (better nutrition, medicine, instruction, etc) and the tail end of genetic selection, because as women become wiser and freer, less opportunities to make a child was given to extreme genetic outlier in the intelligence department (the corollary is that it also prevails for the other extreme, data seems to confirm that as well)."
Yes, as well as a change in the criteria for a mild mental retardation diagnosis.
"I don't understand the fetish people have for chess. If you take 2 completely noob players, the superior intelligence will probably win but at a very high level it doesn't have that much to do with proper intelligence. It is a lot of rote memorization and psychological warfare in many ways. There is just not enough time to properly calculate all the possible moves (even at end game) for logic/intelligence to be that significant of a factor, it can't hurt for sure but it's doubtful that it can be a significant marker of intelligence. Just in general, I believe intelligent people tend not to like games that much because at the end of the day, it ends up being mostly a pointless competition that doesn't add much to one's life or any other for that matter."
Exactly. Chess requires a certain rather rare talent. But that talent is confined to Chess. I do not know of any great Chess players who have accomplished anything of value outside of Chess.
"For school things, I'm inclined to believe the data but it has a lot more to do with environmental factors than actual intelligence. Turns out that being literate much earlier and being subjected to all kind of mental stimulation ensure a decent floor of intellectual competency; that would be sad if it wasn't the case considering that is the whole point of public school and they didn't achieve these results for all that they cost, that would be a rather pointless waste of ressource."
There is also the fact that school testing and grading have been significantly reduced in the last fifty years.
"I believe it has become fashionable to shit/hate on intelligent people, mock them and decry their efforts which is why there are fewer and fewer truly intelligent people who take part in the public discourse to shape the culture."
That is probably part of it. But remember, politics is the home to those of rapacious megalomaniacal persuasion. Most people of high cognitive ability are more interested in gaining knowledge than power.
Politics is always an issue no matter of which kind or at which level you are talking about, that's for sure. The question is, could we really do without it?
Interesting article. To what extent do you think increasingly cognitively complex western societies have kept their populations reasonably sharp, despite a decline in innate ability? IOW, are IQ scores reasonably accurate measures of these societies’ cognitive performance despite their lowered capacity?
I'm not sure what you mean by "sharp." We've compensated for the decline in cognitive ability through labor specialization, improvements in finding relevant information (via the Internet) and, recently, use of AI. I find it much easier to research an article today than I did twenty years ago.
If, by "sharp," you mean mental acuity, I would say we have less of it today than fifty years ago.
Excellent. A very good pulling together of disparate strands. Thank you.
My impression is that Maths scores never increased, nor did Digit Span (though the easier digits forwards may have creeped up a bit, and the harder digits backwards fallen back).
Would you agree with that?
Yes, that's my impression as well. The shorter and simpler the test, the less we see the Flynn effect.
At school and university, I did better on term papers than on tests. I remember having nightmares long afterwards, in which I would be faced with an insoluble problem or a labyrinth with no exit.
Your comment "In the late nineteenth century, this trajectory began to stall and go into reverse" is interesting. I have no basis to comment on the IQ trajectory (either in agreement or disagreement with your thesis) but I have written - on my own Substack and elsewhere - about another 19th/20th trajectory; one that has had huge significance for our current Western societal discontents. I am talking of a syndrome whereby the offspring of the early muck and brass entrepreneurs tended to not follow in their fathers' hard-nosed footsteps but rather came instead to aspire to be more socially 'sophisticated'….. the beginnings of a nascent Left-leaning (and malcontent) intelligentsia. This is a huge and complex subject, way too big to do justice to in a comment thread but it is a subject, as I say, that I have explored as a major theme of STB.
It's my perception, admittedly mostly based in my gut, that western culture has gradually legitimized self-absorption under the more acceptable term "introspection". This has increased mostly among the middle class, and had previously been tolerated and even expected for females, but this toleration has been extended to males, as well.
In a sense it's a part of the feminization of western culture, for better or for worse.
But one of the side-effects is that it narrows both the scope of one's mental activity to the familiar--one's own preferences, habits, values--while concurrently reducing the amount of time in absolute terms spent on problem-solving external situations that may come one's way. The net effect is to spend a greater portion of one's mental energy plowing and re-plowing the same mental field, without breaking new ground on which to refine one's mental acuity; in essence, it is practice rather than learning--and one does not grow much from practice
I don't know for sure if this actually is in play or not, or even if it has the effect of gradually "dumbing down" those who practice this increased self-absorption.
Daniel Bell addresses this point in "The Cultural Contradictions of Capitalism." https://www.amazon.com/Cultural-Contradictions-Capitalism-20th-Anniversary/dp/0465014992
Thanks for the pointer. I have not read it but have come across references to it down the years and so am aware of its standing. Re his identification of the artist as the primary antinomian cultural force, I have recently had what are for me some uncharacteristically optimistic thoughts....That - given our culture's currently hegemonic decadent progressivism - the most trenchant challenges to its orthodoxies might just possibly eventually emerge more from artist rebels than from dissident politicos. (Not holding my breath though.) I explored this theme here: https://grahamcunningham.substack.com/p/art-will-keep-us-alive
Peter Turchin's 'End Times' addresses this issue in an interesting way.
Lead exposure could be a confounding factor. One study estimates that US lead pollution is responsible for an average IQ loss of 2.6 points per person as of 2015.
https://www.pnas.org/doi/10.1073/pnas.2118631119
For some measures perhaps. Lead exposure wouldn't explain the decline in alleles associated with high educational attainment. As the other commenters point out, lead exposure seems to be declining.
https://blogs.cdc.gov/niosh-science-blog/wp-content/uploads/sites/22/2022/10/by-year-v2.png
Yes, that is true, but as the study points out, at one point, the "average blood–lead level (BLL) for the general US population was routinely three to five times higher than the current reference value for clinical concern and case management referral."
The average person is apt to grossly underestimate the tremendous impact of lead exposure on society. Consider how many people it has killed outright:
"The population attributable fraction of the concentration of lead in blood for all-cause mortality was 18·0% (95% CI 10·9–26·1), which is equivalent to 412 000 deaths annually."
https://www.thelancet.com/journals/lanpub/article/PIIS2468-2667(18)30025-2/fulltext
I agree with you about the allelles being a factor but I should suggest that more highly-strung (and therefore higher-IQ) people could be prone to succumbing to the toxicity first.
But lead exposure is decreasing.
Yes. It seems to have peaked in Gen X.
"One study estimates that US lead pollution is responsible for an average IQ loss of 2.6 points per person as of 2015."
I am not a fan of estimates. Anyone can estimate anything...they are useless.
Yes, the limited data we have suggests that brain size has increased much like IQ scores have increased, though that brain-size data may not be reliable. A more reliable trend, in my opinion, is the increase in intracranial volume over the 20th century (Jantz & Jantz, 2016), which confirms the brain size trend data. That skull-size trend is well-validated, so it is odd to me how researchers of the Flynn effect seem unaware of it.
And it is not just that but many other covariates of actual intelligence have trended over the 20th century in the direction of actual rising intelligence, including those biological traits such as increasing height, increasing adult longevity, decreasing fertility, increasing birth weight, and decreasing child mortality. Not every component of general intelligence would be expected to rise: reaction time and color acuity have either remained the same or fallen (the decrease in vocabulary knowledge seems to be merely an expected shift in language; the current generations have less knowledge of The Beatles and The Rolling Stones, but that does not tell you much). But, most components of g have indeed risen. So, with exceptions, generally both the biological stuff and the social stuff has trended in the direction of increasing intelligence.
So why do we resist the easy inference that intelligence itself has risen? Maybe because it is so highly heritable? Adult height is even more strongly heritable (h^2=90%), and in some populations it has risen by more than two standard deviations (NCD-RisC, 2016). Human DNA hasn't changed enough to explain that change over the 20th century, but it is not even mathematically possible to explain the trend with the 10% environmental remainder. We will need to start taking seriously the possibility of changes in genetic expressions, that being the infamous E word: epigenetics. It allows for the possibility that environmental effects can be heritable. We have not isolated the molecular mechanisms for it, but it is likewise the only possible reason why the phase state between solitary grasshoppers and gregarious locusts is likewise heritable. We simply have no other means to explain it.
The study by Jantz and Jantz (2016) shows an increase in mean American cranial size from c. 1820 to c. 1920, followed by no further improvement (there is no cranial data before 1820). That increase is actually before the time range of the Flynn effect.
I believe that Jantz and Jantz (2016) captured the tail end of an upswing in cognitive evolution that began perhaps in Late Antiquity or the Middle Ages and ended shortly after Victorian times. For the reasons why this increase in cranial size was not a "rebound" due to improvements in nutrition, please read my post at: https://evoandproud.blogspot.com/2019/07/why-did-brain-size-decrease-after-ice.html
I have trouble understanding the argument in your second paragraph. And that means I don't follow your third paragraph either.
If mean intelligence had risen over the 20th century, we would see this rise in the culture. Do you believe that modern culture has become more cognitively demanding? Is recreation more cognitively demanding today than it was in the past? At best, the evidence on this point is weak.
Nor am I convinced, for instance, that adult longevity is a measure of mean intelligence. Or decreasing fertility. In any case, adult longevity has been declining in the US.
Peter Frost,
Thank you for your consideration here. I love drawing attention to the trend of increasing skull size. You may have misread Jantz and Jantz (2016). To quote from the abstract: "Samples were organized into 10-year birth cohorts, with birth years ranging from 1820 to 1990." Not 1920. Their observed trend of increasing skull size covers the full scope of the Industrial Revolution until the current generation. And the 19th century is not the tail end of an upswing, but it was when there was a stall, and the upswing was in the 20th century.
I will put aside the other points I made for now. Thank you.
No, I didn't misread Jantz and Jantz (2016). May I quote from that paper? "[Cranial
size/capacity] exhibits a nadir in the late nineteenth century and recovery until about 1930, much like the cranial module." If you look at Figure 2 (p. 59), you will see that cranial size stops increasing circa 1920.
I wish I could cut and paste that figure into this reply. Unfortunately, that doesn't seem possible.
Jantz, R. L., & Jantz, L. M. (2016). The remarkable change in Euro-American cranial shape and size. Human biology, 88(1), 56-64. https://doi.org/10.13110/humanbiology.88.1.0056
Peter Frost, no worries, I have the full text, and I have studied it. I agree with you partially in that the trend of cranial module is ambiguous in isolation. I preferred a simple linear trend in which the slope would be positive, but you may prefer a higher order fit that would infer a stall at 1920. Simpler fits are generally better, in my opinion, but we not settle on that particular principle to make full sense of it. The study is not just about size but also shape, and the shape trends are much more definitive.
I invite you to look at Figure 1, which clarifies what is really going on, because it is not just the total size but it is more specifically many dimensions that are trending in much more clearly linear directions (though conflicting with respect to size). For BBH (height), BNL (length) and XCB (breadth), the inflection point is at about 1880 for all three trends, proceeding linearly thereafter with no change in slope at 1920 for any of those three dimensions, for both males and females. It means, since the 1880 birth cohorts, our heads have been getting taller, longer, and narrower. A similarly increasing linear fit for cranial module would therefore match those three related trends best.
I looked at this study years ago, but an additional thought just now occurred to me: this set of specific shape trends may be more relevant for the total point of increasing intelligence. Greater length and height at the expense of width would accommodate a greater size of the frontal lobe, the primary seat of general intelligence, at the expense of other brain regions.
I am happy to read your additional thoughts on the matter, regardless of our disagreement.
In other words, White Americans have become longer-headed over the past two centuries. This trend might reflect immigration from southern Europe, or it might be due to improvements in nutrition. I don't know. Anyway, there is no good evidence that long-headed humans are more intelligent than broad-headed humans.
In addition, the cranial data is taken from the Forensic Anthropology Data Bank, which suffers from the same bias I noted in autopsy studies. Initially, the skulls were from condemned criminals or unidentified victims. Other human remains would be given a Christian burial. During the 20th century, cranial data became more representative of the general population. That bias would inevitably create a false impression of increasing brain size.
"So why do we resist the easy inference that intelligence itself has risen?"
Because it has yet to manifest itself in the actions of the U.S. populace, this country has never been so stupid.
"...never been so stupid." I think the elitists of every generation believe they are smarter than the younger folk. But, the total numbers really do tell the opposite story. It is not just increasing IQ scores. It is increasing scores of academic standardized tests, increasing educational achievement, increasing enrollment in calculus courses, and increasing GDP per capita. Like I mentioned, it is also increasing skull size. Like Peter Frost mentioned, it is also increasing brain size; he discounted it, but it accords with increasing skull size and increasing IQ etc. To justify our elderly elitist prejudice that kids today are stupider, we need to cherry pick the trends in favor of decreasing Intelligence. But the big picture really is in the direction of increasing intelligence over the 20th century.
"I think the elitists of every generation believe they are smarter than the younger folk."
You should use the terms 'older generation' and 'wiser'. The older generations are wiser than the younger generations.
"It is not just increasing IQ scores. It is increasing scores of academic standardized tests, increasing educational achievement, increasing enrollment in calculus courses, and increasing GDP per capita."
You failed to mention that tests have been dumbed down, and the number of college students has risen inordinately due to lowered acceptance requirements. The U.S. GDP has lost its meaning because it includes financial products rather than productive output. The distribution of wealth in this country is criminal, and intelligence has very little to do with it, but rapaciousness does.
I do stand by my assertion that this country has never been stupider, and I do not level than on just the young. One only has to be aware of what is happening, on a minimal level, in this country to see that stupidity rules.
Yes, within every generation, the older generation is wiser (I prefer the word "smarter" to denote the objectively measurable raw computing power of the brain) and the next generation is stupider. Every generation would agree with thy movie Idiocracy. But, I am all about the numbers, and the dysgenic theorists need to cherry pick the numbers to prove their point. I will provide further relevant examples: both literacy and numeracy have trended upward all over the world over the twentieth century, if it hasn't already reached a maximum at about 100%. If we are getting stupider, then we generally expect downward trends among countries, but they don't exist. You can dismiss each of all the otherwise-converging data points, but the consilience of the total body of evidence no less stands in favor of a drastically-increasing intelligence trend. The evidence could have stopped at the increasing IQ, and no need to go beyond that. But we also have a large pile of covariates trending in the same direction compared to triflingly few going in the opposite direction.
WE disagree.
"the pool of those who reach the top level of cognitive performance is being decimated.." except in China, where it is already freakishly high and still rising.
We have very limited data from China. The Flynn effect seems to be ongoing in that country, but we have no reason to believe that this increase is a real increase in cognitive ability.
In what way is the Chinese data limited?
The Flynn effect may be ongoing but the nutrition/education/urbanization trend certainly is. Current IQ is 106, heading towards first tier cities' 108.
There have been only four studies on the Flynn effect in China, and three of them are based on small samples. Qi and Xiong (2023) found a Flynn effect among Chinese adults born between 1935 and 1984. However, a lot happened in China between those two years, and it's impossible to tell whether this was a real increase in intelligence or simply an increase in familiarity with test-taking.
Also, there has been no study of generational changes in alleles associated with educational attainment. The evidence I've seen is that fertility has been lower among Han than among non-Han, and lower in the cities than in rural areas.
I agree that cognitive ability is high among the Chinese, but I see no evidence that their mean cognitive ability is rising. If anything, it should be falling, since the best and the brightest tend to go to the big cities, where they end up having no children.
Qi, Y., & Xiong, Y. (2023). Intercohort upsurge of cognitive ability among the general population in China: Evaluating a Flynn effect. Intelligence, 98, 101752. https://doi.org/10.1016/j.intell.2023.101752
The sad part for the United States is its intransigence on IVF embryo selection and genetic enhancement of positive human traits. This attitude will lead to an even larger cognitive performance differential between the two.
Embryo selection for cognitive ability is not realistic at this time (PGS Edu has low predictability for individuals).
On the other hand, I am in favor of assisted reproduction (IVF and surrogacy) because it increases the fertility of those couples who are above-average not only for cognitive ability but also for time preference and other desirable traits.
"Embryo selection for cognitive ability is not realistic at this time (PGS Edu has low predictability for individuals)."
That is exactly why research is imperative in psychometrics and genetics. Always look to the future.
> When I look through her books, I’m struck by the differences between them and the ones published today, not only in font size but also in vocabulary, sentence length and sentence complexity.
I broadly agree with Peter Frost's argument here, but this is a very bad argument that needs to be retired from Flynn Effect discussions with prejudice.
Good writing is crisp and concise. It uses simple words where such suffice. Sentences are short, not meandering and convoluted for their own sake.
On average, today's writing is much better than it was a century ago, at least as judged by commonly accepted rules of what constitutes good writing.
What you focus on is strengthened. The brain like a muscle is adaptable, and certain parts increase in efficiency they more they are stimulated.
Up to a point.
Yes, of course there are parameters.
Yup. Similarly, various people love to say that Raven's Progressive Matrices is a culture-free assessment of intelligence, but (by my accounting) it is probably the most culture-dependent. Answering a certain type of pattern-recognition question is very much a "Western education" trained skill.
Actually, standardized testing was introduced into Western education at a very late date. In the late 19th century, it was still condemned as a Chinese idea and was not widely introduced into the school system until the early 20th century:
"When the report was brought up in parliament in 1853, Lord Monteagle argued against the implementation of open examinations because it was a Chinese system and China was not an "enlightened country." Lord Stanley called the examinations the "Chinese Principle." The Earl of Granville did not deny this but argued in favor of the examination system, considering that the minority Manchus had been able to rule China with it for over 200 years. In 1854, Edwin Chadwick reported that some noblemen did not agree with the measures introduced because they were Chinese. The examination system was finally implemented in the British Indian Civil Service in 1855, prior to which admission into the civil service was purely a matter of patronage, and in England in 1870. Even as late as ten years after the competitive examination plan was passed, people still attacked it as an "adopted Chinese culture."
https://en.wikipedia.org/wiki/Exam
"Culture is a product of intelligence. It is the portion of our environment that we design and create through mental effort."
If people's actions are indicative of intelligence, using the United States as an example, intelligence is dropping precipitously. Stupid is as stupid does. Way too many people in this country are stupid on a stick.
"Intelligence researcher Robert Howard (1999, 2001, 2005) cites four pieces of evidence for a real increase in intelligence:
A decrease in the prevalence of mild mental retardation
An increase in the number of chess players reaching top performance at earlier ages
An increase in the number of journal articles and patents each year
An increase in the practical ability of schoolchildren, albeit without a corresponding increase in average general intelligence, in ability to do school work, and in literacy skills (according to a survey of high school teachers who have taught for over 20 years)."
The author is too kind to Mr. Howard, describing the data as debatable. It is fraught with misinterpretation of data and disregard for obvious explanations for the apparent increase in intelligence other than an actual increase in cognitive ability.
Yes, this is my gut reaction. I lived through the late 20th century and knew many ordinary people from the early and mid-20th century. They read books like we now watch cable TV. Many novels of that time were initially published as instalments in popular newspapers.
"They read books like we now watch cable TV. Many novels of that time were initially published as instalments in popular newspapers."
I was also there and concur. While reading novels does increase reading ability, it is mostly entertainment. My preference is to read for knowledge.
I agree that it doesn't have much to do with actual intelligence. All this is just testing for deliberate practice and hyperspecializing in a particular skillset.
The reason this happens is because we put a lot of systems in place that greatly reward this behavior, in fact my opinion is that it disproportionately rewards this type of endeavor that is mostly pointless in the grand scheme of things.
At the end of the day, you quickly figure out that there is not a particular strong correlation between the best at a particular activity (taking school test being one of them) and actual "practical intelligence"; sometime they do go together but it is hardly guaranteed.
The decrease in mild mental retardation could be muh easier attributed to better environmental factor (better nutrition, medicine, instruction, etc) and the tail end of genetic selection, because as women become wiser and freer, less opportunities to make a child was given to extreme genetic outlier in the intelligence department (the corollary is that it also prevails for the other extreme, data seems to confirm that as well).
I don't understand the fetish people have for chess. If you take 2 completely noob players, the superior intelligence will probably win but at a very high level it doesn't have that much to do with proper intelligence. It is a lot of rote memorization and psychological warfare in many ways. There is just not enough time to properly calculate all the possible moves (even at end game) for logic/intelligence to be that significant of a factor, it can't hurt for sure but it's doubtful that it can be a significant marker of intelligence. Just in general I believe intelligent people tend not to like games that much because at the end of the day it ends up being mostly a pointless competition that doesn't add much to one's life or any other for that matter.
For school things, I'm inclined to believe the data but it has a lot more to do with environmental factors than actual intelligence. Turns out that being literate much earlier and being subjected to all kind of mental stimulation ensure a decent floor of intellectual competency; that would be sad if it wasn't the case considering that is the whole point of public school and they didn't achieve these results for all that they cost, that would be a rather pointless waste of ressource.
Culture is indeed a reflection of the intelligence of its stewards and I agree that it is most likely dropping not just in the US but in general in the western world.
I believe it has become fashionable to shit/hate on intelligent people, mock them and decry their efforts which is why there are fewer and fewer truly intelligent people who take part in the public discourse to shape the culture.
Social media also has given too much voice to a majority of idiots who effortlessly overwhelm any kind of effort to establish a higher level of discourse by more intelligent people.
The Greek philosophers had already warned about this in their writing, in that true democracy is not actually desirable because while everybody will have an opinion and things to say about anything they cannot be given the same value depending on who is actually emitting the opinion.
Social media and modern politics give the opportunity for even the worse specimens of humans to give their opinion and influence the trajectory of culture and things alike. For obvious statistical reasons they outnumber the more desirable part and other times it will inexorably regress to a less optimum mean.
People seem to be confused about all this but even if you are an optimist, when you push things to their logical conclusion this is the "best solution" you can find.
I believe that across the ages, the boom and busts of different civilization/society is very likely to be linked to such factor, the better the society is doing, the more inclusive it is of "lesser" people but the more it led it to its natural ending, logicaly...
"The decrease in mild mental retardation could be muh easier attributed to better environmental factor (better nutrition, medicine, instruction, etc) and the tail end of genetic selection, because as women become wiser and freer, less opportunities to make a child was given to extreme genetic outlier in the intelligence department (the corollary is that it also prevails for the other extreme, data seems to confirm that as well)."
Yes, as well as a change in the criteria for a mild mental retardation diagnosis.
"I don't understand the fetish people have for chess. If you take 2 completely noob players, the superior intelligence will probably win but at a very high level it doesn't have that much to do with proper intelligence. It is a lot of rote memorization and psychological warfare in many ways. There is just not enough time to properly calculate all the possible moves (even at end game) for logic/intelligence to be that significant of a factor, it can't hurt for sure but it's doubtful that it can be a significant marker of intelligence. Just in general, I believe intelligent people tend not to like games that much because at the end of the day, it ends up being mostly a pointless competition that doesn't add much to one's life or any other for that matter."
Exactly. Chess requires a certain rather rare talent. But that talent is confined to Chess. I do not know of any great Chess players who have accomplished anything of value outside of Chess.
"For school things, I'm inclined to believe the data but it has a lot more to do with environmental factors than actual intelligence. Turns out that being literate much earlier and being subjected to all kind of mental stimulation ensure a decent floor of intellectual competency; that would be sad if it wasn't the case considering that is the whole point of public school and they didn't achieve these results for all that they cost, that would be a rather pointless waste of ressource."
There is also the fact that school testing and grading have been significantly reduced in the last fifty years.
"I believe it has become fashionable to shit/hate on intelligent people, mock them and decry their efforts which is why there are fewer and fewer truly intelligent people who take part in the public discourse to shape the culture."
That is probably part of it. But remember, politics is the home to those of rapacious megalomaniacal persuasion. Most people of high cognitive ability are more interested in gaining knowledge than power.
Thanks for your reply.
I do agree with your comments too.
Politics is always an issue no matter of which kind or at which level you are talking about, that's for sure. The question is, could we really do without it?
Thank you as well!