This study seems to base its conclusions for the most part on a study from 2016[0] and a study limited to Norway[1]. Both of these studies base their findings on data from 1995-2005 (with the exception of the Netherlands and Britain which both span larger periods) this data itself is collected from variety of experiments with varying sample size and testing methodologies.
There certainly appears to be something interesting here, but I'd be hesitant to draw any conclusions from this data the way TFA does, which reeks a bit of sensationalism. At best I'd call it something worth investigating more thoroughly, at worst it's statistical noise.
This is the kind of study where I expect in a few months to see headlines about IQ NOT dropping, and then more headlines about how IQ is dropping and in the end the whole thing is inconclusive.
The more attention grabbing the headline is the more skeptical I am of the study.
>Substantial gains in GA were apparent from the mid 1950s (test years) to the end 1960s–early 1970s, followed by a decreasing gain rate and a complete stop from the mid 1990s. [...] It is concluded that the Flynn effect may have come to an end in Norway.
The single and/or the first children have higher IQ, so the Flynn effect is a reverse to the number of children per family, ie. it is a reverse to that graph:
I wish that I saw more of these comments on HN links to science articles that explain some research paper. From now on, every such comment that analyzes the underlying study's power and significance, I'm going to upvote, as a general policy.
So it's reversion to mean which is often seen in nature. If we see that today we don't really need high IQ to navigate our way through the cities, nation or even continent because we've GPS and other technologies which drastically reduce the amount of complexity we need to keep up with. Why should a higher IQ exist then?
If we look at the past and see when and where the IQ increase took place, we see it increasing when when we were required to complex terrain and protect ourselves from harsh climate.
Intelligence has been strongly linked with physical fitness, specifically cardiovascular fitness. Is it any surprise as humans have become less active that our intelligence has suffered as well?
If I had to take a bet, I would bet on a combination of a shortened attention span and unknown long-term effects of technology on the brain development plus environmental factors (for example, it seems like plastics are having an impact in things such as fertility rates and our hormonal balance. This could cause other unknown effects).
More cohorts of people are entering the so-called "lower" classes and with this likely comes factors that affect mental aptitude such as decrease in quantity of healthy food consumed and unchallenging jobs.
This would agree with the study, which shows that families' IQs are getting lower with each generation.
I recently managed to nudge my German cousin into reading. Having been raised on consoles and Spongebob, he never enjoyed the written word and was more of a thrillseeker, getting into trouble with a gang of his friends that landed him in custody for a couple months. I started talking to him about Goethe's "Faust", which I was reading at the time, and suggested he take it up. He told me his probation officer nearly fell off her chair when he said he was reading "Faust"; seasoned academics shy away from it.
Yesterday he said he read through 2 GoT books over the course of a weekend and asked me if reading raises IQ. I cited that famous "Freakonomics" chapter that correlates having books with high IQ but can't define a causal link between the two. I told him reading allows us to see patterns in the world around us, which is what IQ testing tests for, therefore if he can detect patterns through reading that apply to the real world he'll be increasing his IQ by reading.
While the link to is might not be clear, it certainly has been shown to improve empathy, which in itself is an important ability for success in life. Alos of course knowledge, awareness of the world, expressiveness/language skills/vocabulary, ...
This is totally my opinion, but I always think articles like these are totally bunk, laughably. I seriously doubt the world is getting dumber. I've seen these assessments, my kids have had to participate in them. I've found them to be either biased or subjective on several occasions. It depends on things like the disposition of the person giving the assessment. (I saw this on when seeing someone take the Stanford Binet assessment.) I'm not saying this happens on all of them, but that along with wild claims about IQs "dropping" makes me question their results.
It seems obvious to me that the proliferation of mobile devices is going to make people dumber.
People offload to these things tasks that were previously given to the brain.
Some of those tasks were mundane; yet, even mundane tasks exercise the brain better than no tasks.
The device substitutes for memory, both short term and long term. Why try to remember something? Snap an image, stupid! Lost? Doh, turn on GPS, crack open Maps. Why bother knowing anything by heart? The Wikipedia has your back; you can instantly access a detailed article featuring more than you'd ever want to know on almost any topic in any knowledge area. Skimming through text to find something? Just use search! Alphabetically searching through a paper dictionary? You're kidding, right? Paper magazine? Holy crap, why: you can't click on the table of contents. You have to read a number, then hold it in your head while finding a page that has the same number in the corner! Why would you do that to yourself?
Devices can easily be turned into tools to boost cognition; that's just not fun though, and not how most people use them. Some games are good for certain cognitive skills. There are applications for learning. Mobile devices are great for foreign language learning: you can train your vocabulary, or review audio-visual materials, anywhere.
Why stop there? Maybe the decline started with the invention of writing. Here's Socrates:
But when it came to writing Theuth said, 'Here, O king, is a branch of learning that will make the people of Egypt wiser and improve their memories; my discovery provides a recipe for memory and wisdom.' But the king answered and said, 'O man full of arts, to one it is given to create the things of art, and to another to judge what measure of harm and of profit they have for those that shall employ them. And so it is that you, by reasons of your tender regard for the writing that is your offspring, have declared the very opposite of its true effect. If men learn this, it will implant forgetfulness in their souls; they will cease to exercise memory because they rely on that which is written, calling things to remembrance no longer from within themselves, but by means of external marks. What you have discovered is a recipe not for memory, but for reminder. And it is no true wisdom that you offer your disciples, but only its semblance, for by telling them of many things without teaching them you will make them seem to know much, while for the most part they know nothing, and as men filled, not with wisdom but with the conceit of wisdom, they will be a burden to their fellows.'
Lots of things that are obvious are wrong. You'd have to show a) we're getting worse at things that we've started offloading to phones (maybe probably true? but demonstrating causation would still be difficult), and if true, b) that IQ tests measure those same things.
Unless you show both of those you haven't shown that dropping IQ rates are related to the proliferation of mobile devices.
>proliferation of mobile devices makes people dumber
In the very 1st week of my PhD studies, we had a host of eminent researchers advising us on how to succeed in graduate studies. One of those professors put up a slide that had a giant 1-line “Don’t use smartphones”
The entire audience - all 30 fresh PhD students, simply took a picture of that slide with their smartphone, just as they did the previous slide & the next one & so on. Not even a hint of irony.
Air pollution is also known to be a potential reason why the Flynn effect (newer generations of test-takers performing substantially better on older tests, accounting also for test familiarity) is declining; with the "IQ curve" over time plateauing. We know that increased presence of CO and CO2 reduces cognitive capacity on many areas.
Carbon monoxide pollution has decreased (or been stable) in the countries I've bothered to check over the last decades (while the Flynn effect was in full swing):
"It is a profoundly erroneous truism, repeated by all copy-books and by eminent people when they are making speeches, that we should cultivate the habit of thinking of what we are doing. The precise opposite is the case. Civilization advances by extending the number of important operations which we can perform without thinking about them. "
-- Alfred North Whitehead
What he is saying is that as civilization advances, the amount we need to think to survive decreases. We don't need high IQ's to survive anymore. While being smart is a selective criterion in a mate, other criteria will tend to overweight IQ when the amount of IQ needed to survive decreases.
Thus, IQ will decrease as civilization advances past a certain threshold. Perhaps we have passed that threshold.
Wow we got really different interpretations out of that quote. In the context of a math textbook, I take that quote to be emphasizing the importance of abstractions and symbols for reasoning effectively.
I don't know if "thinking" in the context of that quote requires high IQ. I think that a high IQ person does less conscious thinking and "just gets" complex problems easily.
I think Alfed Whitehead is supporting IQ rise as civilization advances, since baseline abstractions, problems solving techniques, and patterns are taught to us by our parents / community, and are accumulated over time. We have observed this to be true continuously.
An IQ test is timed and requires pattern recognition and selection for the most part. These things are exactly the type of "operations we perform without thinking" that general intelligence supports. Being good at finding and acting on general patterns without deep thought is extremely helpful and is probably (at least loosely) associated with high IQ.
The further the complexity of civilization exceeds the population's ability to understand it, the more fragile it becomes. People absolutely should cultivate the habit of thinking, because thinking helps us survive disasters.
Not really. He’s talking about the power of mathematical formalism. With a good formalism you just push symbols around following easily memorized rules without thinking about what they mean until you reach your final result.
My first thought was that kids are spending more time on schooling and homework, and less on creative play and unsupervised time outdoors. Childhoods today are very different than 50 years ago.
I wonder when we're going to collectively realize that this epidemic of stupidity is by far the greatest threat facing humanity. It's the reason we're having so much trouble addressing all our other problems, e.g. corrupt government, climate change, etc...
Oof, this is a can of worms...
Can you properly analyze the reasons behind this without going into ethnic differences in IQ? Is it happening in China for instance?
I don't think we should entertain those studies personally, but I'm not sure you can honestly conclude anything about this without that data.
Well, what can I say? We have access to all human knowledge at the palm of our hand, but we don't have the discipline to use it wisely.
1. The rise of social media is a huge contributing factor to misinformation and shortening attention spans.
2. Consumption, consumption, consumption. Most consume but don't create.
3. The unknown effects of technology on our brains. We're all just primates playing with extremely complicated toys. We don't know their effects on us.
> 2. Consumption, consumption, consumption. Most consume but don't create.
That's where I'd put my money. All of a sudden, the need to consume crappy pop culture has exploded around us, and people simply don't do things any more -- "Netflix and chill" has simply pushed other activities aside.
This is, of course, nothing new; it's just that modern streaming services deliver makes it so much more available than it was 30 years ago.
I'm pretty sure the same arguments were made about television, radio, and yes, even books.
If you look at social media today, it's all about creation. You create posts or photos or clever tweets and share them with your peers. This is the opposite of sitting down in front of the television for a few hours to watch corporate-generated programming.
Selection against intelligence should definitely not be ruled out, although there are various environmental issues that could be solved.
Female obesity is known to lead to preganancy complications which cause cognitive deficits.
Obesity in general is known to cause systemic inflammation which affects cognition and speeds up dementia.
The opioid crisis and various other types of drug abuse lead to brain damage.
Various nutritional deficiencies could play a role. Historically, iodine deficiency caused the condition of cretinism, but sub-clinical deficiencies can lead to more subtle effects.
Sleep deprivation is known to cause cognitive deficits, and electronic lights and jobs with nocturnal schedules are more common now. Light pollution and spending too much time indoors during the day throws off our circadian rhythms.
We still have various types of neurotoxins plaguing our environments. More people are living in urban environments now, which causes greater exposure to automobile exhaust. Coal plants are still spewing neurotoxins. Lead pipes are still common in many cities.
High indoor CO2, from poor ventilation, is known to cause cognitive deficits.
The most interesting part is that it hasn't affected the US (yet). The US is probably the leader among developed nations in bad environmentalism, blue screens, bad sleep, opioid addiction, etc... so unless there's a reporting issue in the US, that kind of rules out a lot of those conclusions.
The causal link between obesity and low IQ does not seem to be through systemic inflammation. The research I came across suggests that people with lower IQ are more likely to become obese.
> We observed no evidence that obesity contributed to a decline in IQ, even among obese individuals who displayed evidence of the metabolic syndrome and/or elevated systemic inflammation.
> Overall there was an inverse FIQ/obesity association, except in pre-school children. However, after adjusting for educational attainment, FIQ/obesity association was not significantly different. A lower FIQ in childhood was associated with obesity in later adulthood perhaps with educational level mediating the persistence of obesity in later life.
One huge assumption no one has challenged is the notion that IQ is a valid measure of intelligence. One reason to doubt this is that above a low threshold (80 IIRC), IQ has no correlation with salary.
It is not true that dumber people have more children. At lest not generally:
Cognitive ability and fertility among Swedish men born 1951–1967: evidence from military conscription registers
"We examine the relationship between cognitive ability and childbearing patterns in contemporary Sweden using administrative register data. The topic has a long history in the social sciences and has been the topic of a large number of studies, many reporting a negative gradient between intelligence and fertility. We link fertility histories to military conscription tests with intelligence scores for all Swedish men born 1951–1967. We find a positive relationship between intelligence scores and fertility, and this pattern is consistent across the cohorts we study. The relationship is most pronounced for the transition to a first child, and men with the lowest categories of IQ scores have the fewest children. Using fixed effects models, we additionally control for all factors that are shared by siblings, and after such adjustments, we find a stronger positive relationship between IQ and fertility. Furthermore, we find a positive gradient within groups at different levels of education. Compositional differences of this kind are therefore not responsible for the positive gradient we observe—instead, the relationship is even stronger after controlling for both educational careers and parental background factors. In our models where we compare brothers to one another, we find that, relative to men with IQ 100, the group with the lowest category of cognitive ability have 0.56 fewer children, and men with the highest category have 0.09 more children."
At lest for this group of men, higher iq correlated with more children. There might be something to the belief that dumb people procreate more, but it might also be a stereotype popularized by movies like Idiocracy.
This is the comment that suggests, speciously, that many of the other comments demonstrate the process presented in the article.
The key omission from the article was any hint of a number. Without numbers there is no way to evaluate the claim. Is the purported decline within the range of noise of the measurements?
The lack of numbers is usually a red flag indicating that the author does not want readers evaluating his claims for themselves.
While in this case, I've heard it before and it seems to come from actual scientists, so it's probably not just a journalist's imagination. But in general, I agree that it's frustrating to read articles about trends which don't show numbers, particularly graphs, making it difficult to judge. There are so many articles making scary claims like "X has dropped to half what it was a decade ago!" but it turns out that X fluctuates wildly anyway and the recession or whatever had a massive temporary effect on it.
That said, my 2c is that high IQ causes people to become professionals and being a professional reduces the number of children they have. From my personal observations, poor people seem to have children as their purpose in life while professionals have other purposes and don't feel as much need for children.
Contrast this to most of the last couple of millennia where the highest status men had lots of children to multiple mothers, and famines were common, which would wipe out the poorest people. The poorest people would have included those least able to climb the class hierarchy by being merchants or intelligently winning the games of politics. There also wasn't social welfare to enable the poorest people to support as many children as they want. It sounds like a breeding ground for intelligence.
[+] [-] Pepe1vo|6 years ago|reply
There certainly appears to be something interesting here, but I'd be hesitant to draw any conclusions from this data the way TFA does, which reeks a bit of sensationalism. At best I'd call it something worth investigating more thoroughly, at worst it's statistical noise.
[0] https://www.gwern.net/docs/iq/2016-dutton.pdf
[1] http://differentialclub.wdfiles.com/local--files/assigned-to...
[+] [-] jandrese|6 years ago|reply
The more attention grabbing the headline is the more skeptical I am of the study.
[+] [-] trhway|6 years ago|reply
The single and/or the first children have higher IQ, so the Flynn effect is a reverse to the number of children per family, ie. it is a reverse to that graph:
https://data.worldbank.org/indicator/SP.DYN.TFRT.IN?location...
And on the other side of the world - the "one child” policy results are in:
"An increase of intelligence in China 1986–2012" https://www.sciencedirect.com/science/article/pii/S016028961...
https://data.worldbank.org/indicator/SP.DYN.TFRT.IN?location...
[+] [-] wcunning|6 years ago|reply
[+] [-] rladd|6 years ago|reply
We know that elevated CO2 is negatively correlated with cognitive scores: https://www.yaleclimateconnections.org/2016/07/indoor-co2-du...
[+] [-] gingabriska|6 years ago|reply
If we look at the past and see when and where the IQ increase took place, we see it increasing when when we were required to complex terrain and protect ourselves from harsh climate.
[+] [-] stOneskull|6 years ago|reply
[+] [-] fiftyfifty|6 years ago|reply
https://www.psychologytoday.com/us/blog/quilted-science/2009...
https://www.psychologytoday.com/us/blog/the-athletes-way/201...
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2785721/
https://www.health.harvard.edu/blog/regular-exercise-changes...
[+] [-] amval|6 years ago|reply
Interesting topic, in any case.
[+] [-] s_r_n|6 years ago|reply
More cohorts of people are entering the so-called "lower" classes and with this likely comes factors that affect mental aptitude such as decrease in quantity of healthy food consumed and unchallenging jobs.
This would agree with the study, which shows that families' IQs are getting lower with each generation.
[+] [-] greendestiny_re|6 years ago|reply
Yesterday he said he read through 2 GoT books over the course of a weekend and asked me if reading raises IQ. I cited that famous "Freakonomics" chapter that correlates having books with high IQ but can't define a causal link between the two. I told him reading allows us to see patterns in the world around us, which is what IQ testing tests for, therefore if he can detect patterns through reading that apply to the real world he'll be increasing his IQ by reading.
[+] [-] pergadad|6 years ago|reply
[+] [-] kemiller2002|6 years ago|reply
[+] [-] kazinator|6 years ago|reply
People offload to these things tasks that were previously given to the brain.
Some of those tasks were mundane; yet, even mundane tasks exercise the brain better than no tasks.
The device substitutes for memory, both short term and long term. Why try to remember something? Snap an image, stupid! Lost? Doh, turn on GPS, crack open Maps. Why bother knowing anything by heart? The Wikipedia has your back; you can instantly access a detailed article featuring more than you'd ever want to know on almost any topic in any knowledge area. Skimming through text to find something? Just use search! Alphabetically searching through a paper dictionary? You're kidding, right? Paper magazine? Holy crap, why: you can't click on the table of contents. You have to read a number, then hold it in your head while finding a page that has the same number in the corner! Why would you do that to yourself?
Devices can easily be turned into tools to boost cognition; that's just not fun though, and not how most people use them. Some games are good for certain cognitive skills. There are applications for learning. Mobile devices are great for foreign language learning: you can train your vocabulary, or review audio-visual materials, anywhere.
[+] [-] atdt|6 years ago|reply
But when it came to writing Theuth said, 'Here, O king, is a branch of learning that will make the people of Egypt wiser and improve their memories; my discovery provides a recipe for memory and wisdom.' But the king answered and said, 'O man full of arts, to one it is given to create the things of art, and to another to judge what measure of harm and of profit they have for those that shall employ them. And so it is that you, by reasons of your tender regard for the writing that is your offspring, have declared the very opposite of its true effect. If men learn this, it will implant forgetfulness in their souls; they will cease to exercise memory because they rely on that which is written, calling things to remembrance no longer from within themselves, but by means of external marks. What you have discovered is a recipe not for memory, but for reminder. And it is no true wisdom that you offer your disciples, but only its semblance, for by telling them of many things without teaching them you will make them seem to know much, while for the most part they know nothing, and as men filled, not with wisdom but with the conceit of wisdom, they will be a burden to their fellows.'
(from Phaedrus)
[+] [-] delecti|6 years ago|reply
Unless you show both of those you haven't shown that dropping IQ rates are related to the proliferation of mobile devices.
[+] [-] dxbydt|6 years ago|reply
In the very 1st week of my PhD studies, we had a host of eminent researchers advising us on how to succeed in graduate studies. One of those professors put up a slide that had a giant 1-line “Don’t use smartphones”
The entire audience - all 30 fresh PhD students, simply took a picture of that slide with their smartphone, just as they did the previous slide & the next one & so on. Not even a hint of irony.
That’s when I thought - that ship has sailed.
[+] [-] zmmmmm|6 years ago|reply
[+] [-] hinkley|6 years ago|reply
Having the answers to "everything" at your fingertips may be blunting that for us.
[+] [-] grenoire|6 years ago|reply
[+] [-] FabHK|6 years ago|reply
https://www.epa.gov/air-trends/carbon-monoxide-trends
https://www.epd.gov.hk/epd/english/environmentinhk/air/data/...
https://iir-de.wikidot.com/emission-trends-carbon-monoxide
[+] [-] khrbrt|6 years ago|reply
And a related episode on air pollution in general: https://ashesashes.org/blog/episode-38-dead-air
[+] [-] FabHK|6 years ago|reply
[+] [-] anon1m0us|6 years ago|reply
-- Alfred North Whitehead
What he is saying is that as civilization advances, the amount we need to think to survive decreases. We don't need high IQ's to survive anymore. While being smart is a selective criterion in a mate, other criteria will tend to overweight IQ when the amount of IQ needed to survive decreases.
Thus, IQ will decrease as civilization advances past a certain threshold. Perhaps we have passed that threshold.
[+] [-] helen___keller|6 years ago|reply
[+] [-] jvanderbot|6 years ago|reply
I think Alfed Whitehead is supporting IQ rise as civilization advances, since baseline abstractions, problems solving techniques, and patterns are taught to us by our parents / community, and are accumulated over time. We have observed this to be true continuously.
An IQ test is timed and requires pattern recognition and selection for the most part. These things are exactly the type of "operations we perform without thinking" that general intelligence supports. Being good at finding and acting on general patterns without deep thought is extremely helpful and is probably (at least loosely) associated with high IQ.
[+] [-] mrob|6 years ago|reply
[+] [-] User23|6 years ago|reply
[+] [-] lohszvu|6 years ago|reply
[+] [-] rb808|6 years ago|reply
[+] [-] screye|6 years ago|reply
In previous decades the group of people taking IQ tests might have belonged to a resource rich group.
Now that IQ tests are more commonplace, we might finally be getting more signal from the below median side of the bell curve.
The article didn't mention if these biases were accounted for, and it is a critical detail to leave out.
[+] [-] rnernento|6 years ago|reply
[+] [-] ramblerman|6 years ago|reply
I don't think we should entertain those studies personally, but I'm not sure you can honestly conclude anything about this without that data.
[+] [-] sergiomattei|6 years ago|reply
1. The rise of social media is a huge contributing factor to misinformation and shortening attention spans.
2. Consumption, consumption, consumption. Most consume but don't create.
3. The unknown effects of technology on our brains. We're all just primates playing with extremely complicated toys. We don't know their effects on us.
The next decades will be interesting...
[+] [-] ahje|6 years ago|reply
That's where I'd put my money. All of a sudden, the need to consume crappy pop culture has exploded around us, and people simply don't do things any more -- "Netflix and chill" has simply pushed other activities aside.
This is, of course, nothing new; it's just that modern streaming services deliver makes it so much more available than it was 30 years ago.
[+] [-] fwip|6 years ago|reply
If you look at social media today, it's all about creation. You create posts or photos or clever tweets and share them with your peers. This is the opposite of sitting down in front of the television for a few hours to watch corporate-generated programming.
[+] [-] nwah1|6 years ago|reply
Female obesity is known to lead to preganancy complications which cause cognitive deficits.
Obesity in general is known to cause systemic inflammation which affects cognition and speeds up dementia.
The opioid crisis and various other types of drug abuse lead to brain damage.
Various nutritional deficiencies could play a role. Historically, iodine deficiency caused the condition of cretinism, but sub-clinical deficiencies can lead to more subtle effects.
Sleep deprivation is known to cause cognitive deficits, and electronic lights and jobs with nocturnal schedules are more common now. Light pollution and spending too much time indoors during the day throws off our circadian rhythms.
We still have various types of neurotoxins plaguing our environments. More people are living in urban environments now, which causes greater exposure to automobile exhaust. Coal plants are still spewing neurotoxins. Lead pipes are still common in many cities.
High indoor CO2, from poor ventilation, is known to cause cognitive deficits.
[+] [-] 013a|6 years ago|reply
[+] [-] rockinghigh|6 years ago|reply
> We observed no evidence that obesity contributed to a decline in IQ, even among obese individuals who displayed evidence of the metabolic syndrome and/or elevated systemic inflammation.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3813310/
> Overall there was an inverse FIQ/obesity association, except in pre-school children. However, after adjusting for educational attainment, FIQ/obesity association was not significantly different. A lower FIQ in childhood was associated with obesity in later adulthood perhaps with educational level mediating the persistence of obesity in later life.
https://www.ncbi.nlm.nih.gov/pubmed/19780990
[+] [-] j0057|6 years ago|reply
[+] [-] craftyguy|6 years ago|reply
[deleted]
[+] [-] kkwteh|6 years ago|reply
[+] [-] sanxiyn|6 years ago|reply
https://www.pnas.org/content/115/26/6674
[+] [-] bjourne|6 years ago|reply
Cognitive ability and fertility among Swedish men born 1951–1967: evidence from military conscription registers "We examine the relationship between cognitive ability and childbearing patterns in contemporary Sweden using administrative register data. The topic has a long history in the social sciences and has been the topic of a large number of studies, many reporting a negative gradient between intelligence and fertility. We link fertility histories to military conscription tests with intelligence scores for all Swedish men born 1951–1967. We find a positive relationship between intelligence scores and fertility, and this pattern is consistent across the cohorts we study. The relationship is most pronounced for the transition to a first child, and men with the lowest categories of IQ scores have the fewest children. Using fixed effects models, we additionally control for all factors that are shared by siblings, and after such adjustments, we find a stronger positive relationship between IQ and fertility. Furthermore, we find a positive gradient within groups at different levels of education. Compositional differences of this kind are therefore not responsible for the positive gradient we observe—instead, the relationship is even stronger after controlling for both educational careers and parental background factors. In our models where we compare brothers to one another, we find that, relative to men with IQ 100, the group with the lowest category of cognitive ability have 0.56 fewer children, and men with the highest category have 0.09 more children."
https://royalsocietypublishing.org/doi/10.1098/rspb.2019.035...
At lest for this group of men, higher iq correlated with more children. There might be something to the belief that dumb people procreate more, but it might also be a stereotype popularized by movies like Idiocracy.
[+] [-] ncmncm|6 years ago|reply
The key omission from the article was any hint of a number. Without numbers there is no way to evaluate the claim. Is the purported decline within the range of noise of the measurements?
The lack of numbers is usually a red flag indicating that the author does not want readers evaluating his claims for themselves.
[+] [-] lopmotr|6 years ago|reply
That said, my 2c is that high IQ causes people to become professionals and being a professional reduces the number of children they have. From my personal observations, poor people seem to have children as their purpose in life while professionals have other purposes and don't feel as much need for children.
Contrast this to most of the last couple of millennia where the highest status men had lots of children to multiple mothers, and famines were common, which would wipe out the poorest people. The poorest people would have included those least able to climb the class hierarchy by being merchants or intelligently winning the games of politics. There also wasn't social welfare to enable the poorest people to support as many children as they want. It sounds like a breeding ground for intelligence.