Also any headline given as X in the last Y, for large X, means X in the last Y+1, e.g. 7 of the last 9 means 7 of the last 10 or it would have read 8 of the last 10.
> Since the intelligence test was invented more than 100 years ago, our IQ scores have been steadily increasing. Even the average person today would have been considered a genius compared to someone born in 1919 – a phenomenon known as the Flynn effect.
Hard to see this as anything but an indictment of IQ tests.
People have not gotten smarter so whatever these tests are measuring and however well they predict success, they're not measuring intelligence.
Brain requires a lot of energy to work, so better nutrition will certainly not hurt. However, I believe that if there is some improvement to intelligence due to better nutrition, its effect is negligible compared to improvements due to education, better teaching techniques and near-universal literacy.
I hope other non-educational improvements in child rearing have also had a significant effect. In particular, the widespread acceptance of the idea it's not okay to strike children has hopefully greatly reduced the number of children trying to learn with varying degrees of PTSD.
> there is no reason to believe people haven't gotten smarter as well.
Null hypothesis? By default we don't assume presence of changes, in the absence of reasons for that, and those reasons - that nutrition is causing IQ growth - need to be explained.
There shouldn't be no reasons not to assume something, it's not enough. Sorry for triple negative.
This isn’t a by default issue, this is claiming counterevidence to increase in intelligence that justifies rejecting the validity of IQ in measuring intelligence because it is increasing. The null hypothesis doesn’t support that, only independent evidence of intelligence not increasing would.
> People have not gotten smarter so whatever these tests are measuring and however well they predict success, they're not measuring intelligence.
This is obviously true, except other changes have happened. People have got taller. I'm no expert but I believe that's mostly down to better nutrition. Is it possible that better nutrition has also led to people getting smarter? I'm not sure. I wouldn't bet on it, but it doesn't seem completely impossible either.
Why do you assume this to be the case? All kinds of early-environment things have adverse, lifelong cognitive effects, and both society at large and aware individuals for their own kids have tended to direct energy at reducing exposure to them. People getting smarter is a pretty predictable effect.
> Hard to see this as anything but an indictment of IQ tests.
Careful, there are a lot of people who have an emotional attachment to IQ tests and their implications for determining intelligence. Implying that IQ tests don't measure intelligence usually brings them out of the woodwork.
Careful, there are a lot of people who wish IQ tests didn’t have anything useful to say about intelligence. Implying that IQ tests can be useful tools and that their results might bear some relation to intelligence usually brings them out of the woodwork.
People have definitely gotten smarter. Here’s a small case which might help illustrate how this happens in general: We know infection with hookworms and other soil-transmitted helminths will do nasty things to the intelligence of the patient, especially for children. Since humanity got rich enough to build sewer systems and shoes and anti-parasitic drug companies, soil transmitted helminths have become a lot less of a problem (and the same goes for their cognitive effects).
I just learned about the awful effects of iodine deficiency and how incredibly widespread it once was the other day from a youtube suggestion[1] about iodized salt.
Previously I had thought iodization was mostly for preventing thyroid issues in the event of nuclear fallout, but no! It was a way bigger deal. For example, I had no idea it was the origin of the term "cretin"[2].
My dismissal was too strong but the article says "even the average person today would have been considered a genius compared to someone born in 1919". I find that incredibly hard to believe.
Even if average intelligence has climbed up, genius is about the absolute top of the heap and I doubt that has changed.
> People have not gotten smarter so whatever these tests are measuring and however well they predict success, they're not measuring intelligence.
Another contributor might be that the model of intelligence that the IQ tests is close to a model that is used by education and development experts, and that kids are getting pre-educated in skills that allow them to do better on IQ tests.
Seems this is mostly about average people. On average people today have far better food, medical treatments, education and also chances for mental training. Which means on average people today have better chances to utilize their potential and maintain their individual peak.
This flies in the fact of lots of evidence to the contrary:
1) High-school students now understand mathematics that only advanced degrees would have understood in 1919.
2) High-school musicians now regularly play pieces that were considered meant only for "virtuousos" in 1919.
I can go on and on.
At the very least, your hypothesis that people haven't gotten smarter is quite suspect and demands evidence. The fact that IQ tests (whatever they measure) have shown an aggregate increase is also evidence against your hypothesis.
> This flies in the fact of lots of evidence to the contrary
Your examples are not evidence of higher IQ. They are examples of human progress.
> 1) High-school students now understand mathematics that only advanced degrees would have understood in 1919.
Being the first to do something and following in their footsteps is two very different things.
Sure but that is just because it is better understood now. All this this means is that the idea / technique is better understood and understood by more people.
> 2) High-school musicians now regularly play pieces that were considered meant only for "virtuousos" in 1919.
Again this is just evidence that more people understand how to play the pieces.
Doing something novel and unique is much more difficult than understanding something that is already understood. That is why scientists sometimes say they are standing on the shoulders of giants
> The fact that IQ tests (whatever they measure) have shown an aggregate increase is also evidence against your hypothesis.
You are oversimplying the findings, I made the same mistake when I first heard of the flynn effect. What you are referring to is the Flynn effect. This is where the average IQ increases each generation. While there is an increase of ~3 points every decade, it is on the low end of the distribution
> Some studies have found the gains of the Flynn effect to be particularly concentrated at the lower end of the distribution. Teasdale and Owen (1989), for example, found the effect primarily reduced the number of low-end scores, resulting in an increased number of moderately high scores, with no increase in very high scores. In another study, two large samples of Spanish children were assessed with a 30-year gap. Comparison of the IQ distributions indicated that the mean IQ scores on the test had increased by 9.7 points (the Flynn effect), the gains were concentrated in the lower half of the distribution and negligible in the top half, and the gains gradually decreased as the IQ of the individuals increased. Some studies have found a reverse Flynn effect with declining scores for those with high IQ.
In other words the people with the lowest IQ scores are increasing more greatly and pushing the average up. The whole distribution itself is not moving with it though.
I dislike the whole idea though of IQ as a test of intelligence (which is a nebulous concept in itself). I've seen people with high IQs believe in very ridiculous things and engage in behaviour which most would consider to be stupid.
As someone that did 2 proper IQ tests back in the 90s because my school thought I mentally handicapped (I am dyspraxic so technically I am). The tests are good at identifying whether you are good at abstract reasoning. There are other forms of thinking that I am very bad at even though I am on the higher end of the IQ scale (I was graded at 142 at the time).
Expertise/intelligence/whatever you call it is the ability to handle more complex tasks because you can place the less complex tasks as background tasks.
This follows whether it is due to better education, better training, better tools, or better nutrition.
Are programmers "smarter" than they were 50 years ago? They can certainly create much more complex programs that do MUCH more than we could 50 years ago.
Are chess players "smarter" than they were 100 years ago? ELO ratings sure suggest they are.
Would those people of 100 years ago been able to do the tasks we can now given our current society? Maybe. But that indicates that "intelligence" is also a function of "current environment". And, if the current environment is better, then the humans are "smarter", too.
> Expertise/intelligence/whatever you call it is the ability to handle more complex tasks because you can place the less complex tasks as background tasks.
No it isn't. I have seen otherwise quite smart people completely fail to do the most basic tasks especially when it comes to repair.
You can work it out (I for example can do many home DIY projects now). But just because you can do a complex task in one domain it does not mean you can do a relative simple task in another domain. You can see this in this industry. The number of C# programmers that cannot do simple CSS.
The fact the you can't give it a proper name means that you cannot quantify it properly.
> This follows whether it is due to better education, better training, better tools, or better nutrition.
No it doesn't. Better training for doing X just means you will be better at doing X. It does not say anything about how well you may perform in other taks.
> Are programmers "smarter" than they were 50 years ago? They can certainly create much more complex programs that do MUCH more than we could 50 years ago.
More complex doesn't mean it is better. In fact if you are a good engineer you will know that unnecessarily complexity is a sign of a poor design. So this does not follow what-so-ever.
Also most of the literature written 50 years or more ago from the pioneers of the field are constantly being re-discovered.
So no.
> Are chess players "smarter" than they were 100 years ago? ELO ratings sure suggest they are.
No. No. No. Just because a number goes up, doesn't mean that everyone is getting better. It could be because weaker players may not bother at all with such matches where they are rated, while better players are more likely to participate in any ranked or scoring system. So you cannot draw that conclusion.
> Would those people of 100 years ago been able to do the tasks we can now given our current society? Maybe. But that indicates that "intelligence" is also a function of "current environment". And, if the current environment is better, then the humans are "smarter", to
No I am sorry that conclusion is incorrect. There are many here that would struggle doing some very basic things in other fields especially if it involved their hands (carpentry, joining, brick laying) because they have no expertise in it and those fields have been around a very long time. So you cannot come to that conclusion at all.
It’s a fairly easy call on the existence of a finite upper bound, even if we can eventually start distributing a person’s intelligence to components outside their skull.
To me there's a big question of what social processes we have that push towards intelligence, and which push towards more base systems.
The modern, mass-accessible internet is ~10 years old. Maybe a little older, maybe a little less. A huge amount of the drive has been to onboard everyone, to get new users, at any cost. Via design that makes sure everything is easy & accessible. Even more so, new incipient media & hypermedia has emerged to capture eyeballs. It's been a race to the bottom for the attention economy. On the one hand we do have a broad competition to fascinate people, to show them interesting things, and huge troves of videos to engage in, but my feeling remains that we've created a fairly superficial net in which to capture attention.
This will not hold forever. At some point, society & humanity will start to emerge some desire, some sense, to escape the baser levels, & to find more sophisticated, positively reinforcing forces will emerge. Particularly with so many abusers & manipulators & bad actors, the desire to have better considered information, of a higher refinement, is something that I look forward to people seeking.
On another level: I do fret that globalization has destroyed the need for polymaths, for the well considered competent doers of the world. I fret that specialization & concentrated industry shield humankind from itself, that we have hidden much of the world about us behind a shroud. Computers, sadly, are one of the worst offenders here, although I think changing that is one of the most possible & most useful ways to re-instill a locus of control, to put people back in touch with the mechanisms of the world.
Little of this bears close resemblence to the discussion on IQ, but to me, IQ follows behind the questions of what society engages in, what it's focus is. I believe the older industrializing world had a physicality & reality to it, an emerging-ness, that emphasized the importance of intelligence, reasoning and science: the push for Enlightenment was still real to that older world, and that drove the pursuit of intellect.
> It's been a race to the bottom for the attention economy.
Sadly, with the added knock-on effect of making more in-depth sorts of entertainment / mass culture less profitable, further degrading public discourse..
Being entertained by an endless scroll of memes or political cartoons is alot different than reading full news articles or entertainment pieces, but unfortunately there is enough of the former content to 'fill the void' that the second kind has difficulty 'competing'
I have similar feelings on a larger span of modern life. A big word this day is availability. As today everybody should be able to have every possible capability on their smartphone. And I think it's misguided (but a natural effect of the capacity for modern societies to produce everything fast and cheap now).. it confuses tool for craft. And yeah it kinda creates a race to the bottom, at least as long as the belief holds on the large. One day people will realize that no matter what you give to the mass, only few people will have grit/stamina/talent/luck to do something special with it, and oh surprise, turns out they used a VCR and a piece of cardboard, not your deeplearning infused movie infering app of the day.
> Population intelligence quotients increased throughout the 20th century—a phenomenon known as the Flynn effect—although recent years have seen a slowdown or reversal of this trend in several countries. To distinguish between the large set of proposed explanations, we categorize hypothesized causal factors by whether they accommodate the existence of within-family Flynn effects. Using administrative register data and cognitive ability scores from military conscription data covering three decades of Norwegian birth cohorts (1962–1991), we show that the observed Flynn effect, its turning point, and subsequent decline can all be fully recovered from within-family variation. The analysis controls for all factors shared by siblings and finds no evidence for prominent causal hypotheses of the decline implicating genes and environmental factors that vary between, but not within, families.
Probably not. Human has been known to augment intelligence with tool usage throughout history. Better tools will come along and the human+tool fusion will move forward in the intelligence department.
FWIW-W, Susan Blackmore in her 1999 book, the Meme Machine, notes there appears to be an equilibrium for brain size. Neanderthal had a bigger brain size than modern humans. The larger brain requires more calories, and increases mortality for the mother.
Blackmore, Susan. The Meme Machine, Oxford and New York, Oxford University Press 1999
Intelligence varies between populations, and the ratio changes, eg European IQ probably dropped from 1930-1945 due to genocide of a high IQ population.
Some places are growing much faster than others, eg Europe had twice the population of Africa in 1950 and soon it will have half.
So both groups got smarter, but the global average dropped.
Going forward things don't look good, the highest IQ countries like Singapore and South Korea have ~1 TFR so are on track to halve in size each generation (against a growing world)
I question the underlying assumption that the average person is more intelligent today than 100 years ago or even 20,000 years ago.
Yes, the Flynn Effect is real. IQ scores have risen internationally over the past 100 years, but that's more likely due to greater access to education and education systems that teach the kind of test-taking skills that IQ tests measure.
IN the US, the average GPA have been increasing for both HS and colleges, but that's almost certainly not evidence of an increase in general intelligence.
It takes for more intelligence to create today's technology and society than that of 100 or 20,000 years ago, but it requires far less intelligence for an individual to survive in today's society than it did to survive 20,000 years ago.
For example, 20,000 years ago if you wanted to eat you needed to be able to distinguish between dozens of subtly different berries and mushrooms with no books or reference works. Make the wrong choice and you die.
Today you just push a few buttons on your smartphone.
Edit:
Better nutrition has definitely had an effect on the average number, so I guess I'm really talking about a hypothetical well-fed human not exposed to toxic chemicals at any point in time.
> it requires far less intelligence for an individual to survive in today's society than it did to survive 20,000 years ago.
Survive, perhaps yes. But to simply process the world around you? How much mental stimuli did you have sitting in the forest and doing menial labour much of the day, collecting and discerning berries which you were likely taught to eat by your parents/community anyway.
Versus the mental stimuli of a 24/7 worldwide news cycle. We may feel much of our media is superficial, and indeed compared to reading a great book it is. But at the same time I've researched the local real estate market and did some calculations. I got updated on a complex political scandal in my country (Netherlands) which affects multiple institutions and puts our governance system in question and relates to the last 10 years of political history. I've listed much of the evening to Punjabi music. I browsed an online market with thousands of articles with designs I'd never seen before to look for a friends' birthday gift. I read about the discovery of Neptune by way of mathematical deduction even before it was actually observed. I watched a Tik Tok dance. I watched an hour of two elite competitors in a 4X strategy game (Supcom) tournament. I read about a blind person's eye being repaired, but needing years of training to be able to process and understand the new stimuli. And I spent a few hours playing a space exploration/rpg/colonybuilding game, managing a fleet and a number of colonies.
In all of this I posit I did vastly more mental calculation than the guy in the forest. And it's just an ordinary Sunday, a day of leisure instead of my job which is a constant mental challenge, even if somewhat soulless at times.
Hell, even spending time in a large supermarket making permutations of tens of thousands of meals. The average supermarket has 20-40 thousand items. Processing prices versus weight/size/marketing info, is likely a bigger daily mental hurdle than picking grain and grinding it into flower and baking bread and eating that.
> How much mental stimuli did you have sitting in the forest and doing menial labour much of the day,
Quite a bit, I imagine.
We tend to discount the complexity of tasks we don't have to do. In the same way you dismiss the complexities of living off the land as "sitting in a forest", someone could uncharitably describe your day as "sitting in front of a computer."
Also, be careful not to confuse the importance of the subject matter or tool with the difficulty of the task. Reading about the discovery of Neptune or a political scandal likely requires much less mental activity than identifying an animal by its tracks and then tracking it though a forest.
60 comments
[ 2.9 ms ] story [ 125 ms ] threadHard to see this as anything but an indictment of IQ tests.
People have not gotten smarter so whatever these tests are measuring and however well they predict success, they're not measuring intelligence.
Null hypothesis? By default we don't assume presence of changes, in the absence of reasons for that, and those reasons - that nutrition is causing IQ growth - need to be explained.
There shouldn't be no reasons not to assume something, it's not enough. Sorry for triple negative.
This isn’t a by default issue, this is claiming counterevidence to increase in intelligence that justifies rejecting the validity of IQ in measuring intelligence because it is increasing. The null hypothesis doesn’t support that, only independent evidence of intelligence not increasing would.
The idea that evolution stops at the neck seems completely laughable to me.
[0]https://www.gwern.net/Mistakes#iq
This is obviously true, except other changes have happened. People have got taller. I'm no expert but I believe that's mostly down to better nutrition. Is it possible that better nutrition has also led to people getting smarter? I'm not sure. I wouldn't bet on it, but it doesn't seem completely impossible either.
If you count lead paint "wall candy" chips, nutrition definitely has improved intelligence.
Why do you assume this to be the case? All kinds of early-environment things have adverse, lifelong cognitive effects, and both society at large and aware individuals for their own kids have tended to direct energy at reducing exposure to them. People getting smarter is a pretty predictable effect.
Careful, there are a lot of people who have an emotional attachment to IQ tests and their implications for determining intelligence. Implying that IQ tests don't measure intelligence usually brings them out of the woodwork.
Previously I had thought iodization was mostly for preventing thyroid issues in the event of nuclear fallout, but no! It was a way bigger deal. For example, I had no idea it was the origin of the term "cretin"[2].
1 - https://youtu.be/B00K66HivcI
2 - https://en.m.wikipedia.org/wiki/Cretin
I actually had to buy the cheapest 99 cent salt shaker to get one with iodine and I add a few sprinkles to most of my kids meals. Just to be safe.
Even if average intelligence has climbed up, genius is about the absolute top of the heap and I doubt that has changed.
Another contributor might be that the model of intelligence that the IQ tests is close to a model that is used by education and development experts, and that kids are getting pre-educated in skills that allow them to do better on IQ tests.
This flies in the fact of lots of evidence to the contrary:
1) High-school students now understand mathematics that only advanced degrees would have understood in 1919.
2) High-school musicians now regularly play pieces that were considered meant only for "virtuousos" in 1919.
I can go on and on.
At the very least, your hypothesis that people haven't gotten smarter is quite suspect and demands evidence. The fact that IQ tests (whatever they measure) have shown an aggregate increase is also evidence against your hypothesis.
Your examples are not evidence of higher IQ. They are examples of human progress.
> 1) High-school students now understand mathematics that only advanced degrees would have understood in 1919.
Being the first to do something and following in their footsteps is two very different things.
Sure but that is just because it is better understood now. All this this means is that the idea / technique is better understood and understood by more people.
> 2) High-school musicians now regularly play pieces that were considered meant only for "virtuousos" in 1919.
Again this is just evidence that more people understand how to play the pieces.
Doing something novel and unique is much more difficult than understanding something that is already understood. That is why scientists sometimes say they are standing on the shoulders of giants
> The fact that IQ tests (whatever they measure) have shown an aggregate increase is also evidence against your hypothesis.
You are oversimplying the findings, I made the same mistake when I first heard of the flynn effect. What you are referring to is the Flynn effect. This is where the average IQ increases each generation. While there is an increase of ~3 points every decade, it is on the low end of the distribution
https://en.wikipedia.org/wiki/Flynn_effect#Rise_in_IQ
> Some studies have found the gains of the Flynn effect to be particularly concentrated at the lower end of the distribution. Teasdale and Owen (1989), for example, found the effect primarily reduced the number of low-end scores, resulting in an increased number of moderately high scores, with no increase in very high scores. In another study, two large samples of Spanish children were assessed with a 30-year gap. Comparison of the IQ distributions indicated that the mean IQ scores on the test had increased by 9.7 points (the Flynn effect), the gains were concentrated in the lower half of the distribution and negligible in the top half, and the gains gradually decreased as the IQ of the individuals increased. Some studies have found a reverse Flynn effect with declining scores for those with high IQ.
In other words the people with the lowest IQ scores are increasing more greatly and pushing the average up. The whole distribution itself is not moving with it though.
I dislike the whole idea though of IQ as a test of intelligence (which is a nebulous concept in itself). I've seen people with high IQs believe in very ridiculous things and engage in behaviour which most would consider to be stupid.
As someone that did 2 proper IQ tests back in the 90s because my school thought I mentally handicapped (I am dyspraxic so technically I am). The tests are good at identifying whether you are good at abstract reasoning. There are other forms of thinking that I am very bad at even though I am on the higher end of the IQ scale (I was graded at 142 at the time).
This follows whether it is due to better education, better training, better tools, or better nutrition.
Are programmers "smarter" than they were 50 years ago? They can certainly create much more complex programs that do MUCH more than we could 50 years ago.
Are chess players "smarter" than they were 100 years ago? ELO ratings sure suggest they are.
Would those people of 100 years ago been able to do the tasks we can now given our current society? Maybe. But that indicates that "intelligence" is also a function of "current environment". And, if the current environment is better, then the humans are "smarter", too.
No it isn't. I have seen otherwise quite smart people completely fail to do the most basic tasks especially when it comes to repair.
You can work it out (I for example can do many home DIY projects now). But just because you can do a complex task in one domain it does not mean you can do a relative simple task in another domain. You can see this in this industry. The number of C# programmers that cannot do simple CSS.
The fact the you can't give it a proper name means that you cannot quantify it properly.
> This follows whether it is due to better education, better training, better tools, or better nutrition.
No it doesn't. Better training for doing X just means you will be better at doing X. It does not say anything about how well you may perform in other taks.
> Are programmers "smarter" than they were 50 years ago? They can certainly create much more complex programs that do MUCH more than we could 50 years ago.
More complex doesn't mean it is better. In fact if you are a good engineer you will know that unnecessarily complexity is a sign of a poor design. So this does not follow what-so-ever.
Also most of the literature written 50 years or more ago from the pioneers of the field are constantly being re-discovered.
So no.
> Are chess players "smarter" than they were 100 years ago? ELO ratings sure suggest they are.
No. No. No. Just because a number goes up, doesn't mean that everyone is getting better. It could be because weaker players may not bother at all with such matches where they are rated, while better players are more likely to participate in any ranked or scoring system. So you cannot draw that conclusion.
> Would those people of 100 years ago been able to do the tasks we can now given our current society? Maybe. But that indicates that "intelligence" is also a function of "current environment". And, if the current environment is better, then the humans are "smarter", to
No I am sorry that conclusion is incorrect. There are many here that would struggle doing some very basic things in other fields especially if it involved their hands (carpentry, joining, brick laying) because they have no expertise in it and those fields have been around a very long time. So you cannot come to that conclusion at all.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2776484/
The modern, mass-accessible internet is ~10 years old. Maybe a little older, maybe a little less. A huge amount of the drive has been to onboard everyone, to get new users, at any cost. Via design that makes sure everything is easy & accessible. Even more so, new incipient media & hypermedia has emerged to capture eyeballs. It's been a race to the bottom for the attention economy. On the one hand we do have a broad competition to fascinate people, to show them interesting things, and huge troves of videos to engage in, but my feeling remains that we've created a fairly superficial net in which to capture attention.
This will not hold forever. At some point, society & humanity will start to emerge some desire, some sense, to escape the baser levels, & to find more sophisticated, positively reinforcing forces will emerge. Particularly with so many abusers & manipulators & bad actors, the desire to have better considered information, of a higher refinement, is something that I look forward to people seeking.
On another level: I do fret that globalization has destroyed the need for polymaths, for the well considered competent doers of the world. I fret that specialization & concentrated industry shield humankind from itself, that we have hidden much of the world about us behind a shroud. Computers, sadly, are one of the worst offenders here, although I think changing that is one of the most possible & most useful ways to re-instill a locus of control, to put people back in touch with the mechanisms of the world.
Little of this bears close resemblence to the discussion on IQ, but to me, IQ follows behind the questions of what society engages in, what it's focus is. I believe the older industrializing world had a physicality & reality to it, an emerging-ness, that emphasized the importance of intelligence, reasoning and science: the push for Enlightenment was still real to that older world, and that drove the pursuit of intellect.
Sadly, with the added knock-on effect of making more in-depth sorts of entertainment / mass culture less profitable, further degrading public discourse..
Being entertained by an endless scroll of memes or political cartoons is alot different than reading full news articles or entertainment pieces, but unfortunately there is enough of the former content to 'fill the void' that the second kind has difficulty 'competing'
https://www.sciencedirect.com/science/article/abs/pii/S01602...
It mentions gains in the US and losses in Western Europe. Could it just be economically motivated ‘brain drain’?
Abstract:
> Population intelligence quotients increased throughout the 20th century—a phenomenon known as the Flynn effect—although recent years have seen a slowdown or reversal of this trend in several countries. To distinguish between the large set of proposed explanations, we categorize hypothesized causal factors by whether they accommodate the existence of within-family Flynn effects. Using administrative register data and cognitive ability scores from military conscription data covering three decades of Norwegian birth cohorts (1962–1991), we show that the observed Flynn effect, its turning point, and subsequent decline can all be fully recovered from within-family variation. The analysis controls for all factors shared by siblings and finds no evidence for prominent causal hypotheses of the decline implicating genes and environmental factors that vary between, but not within, families.
Search internet for more info.
The first link I found:
> Based on measurements of skulls, the average brain volume of Homo sapiens has reportedly decreased by roughly 10 percent in the past 40,000 years.
https://www.discovermagazine.com/planet-earth/the-human-brai...
Blackmore, Susan. The Meme Machine, Oxford and New York, Oxford University Press 1999
Intelligence varies between populations, and the ratio changes, eg European IQ probably dropped from 1930-1945 due to genocide of a high IQ population.
Some places are growing much faster than others, eg Europe had twice the population of Africa in 1950 and soon it will have half.
So both groups got smarter, but the global average dropped.
Going forward things don't look good, the highest IQ countries like Singapore and South Korea have ~1 TFR so are on track to halve in size each generation (against a growing world)
Yes, the Flynn Effect is real. IQ scores have risen internationally over the past 100 years, but that's more likely due to greater access to education and education systems that teach the kind of test-taking skills that IQ tests measure.
IN the US, the average GPA have been increasing for both HS and colleges, but that's almost certainly not evidence of an increase in general intelligence.
It takes for more intelligence to create today's technology and society than that of 100 or 20,000 years ago, but it requires far less intelligence for an individual to survive in today's society than it did to survive 20,000 years ago.
For example, 20,000 years ago if you wanted to eat you needed to be able to distinguish between dozens of subtly different berries and mushrooms with no books or reference works. Make the wrong choice and you die.
Today you just push a few buttons on your smartphone.
Edit: Better nutrition has definitely had an effect on the average number, so I guess I'm really talking about a hypothetical well-fed human not exposed to toxic chemicals at any point in time.
Survive, perhaps yes. But to simply process the world around you? How much mental stimuli did you have sitting in the forest and doing menial labour much of the day, collecting and discerning berries which you were likely taught to eat by your parents/community anyway.
Versus the mental stimuli of a 24/7 worldwide news cycle. We may feel much of our media is superficial, and indeed compared to reading a great book it is. But at the same time I've researched the local real estate market and did some calculations. I got updated on a complex political scandal in my country (Netherlands) which affects multiple institutions and puts our governance system in question and relates to the last 10 years of political history. I've listed much of the evening to Punjabi music. I browsed an online market with thousands of articles with designs I'd never seen before to look for a friends' birthday gift. I read about the discovery of Neptune by way of mathematical deduction even before it was actually observed. I watched a Tik Tok dance. I watched an hour of two elite competitors in a 4X strategy game (Supcom) tournament. I read about a blind person's eye being repaired, but needing years of training to be able to process and understand the new stimuli. And I spent a few hours playing a space exploration/rpg/colonybuilding game, managing a fleet and a number of colonies.
In all of this I posit I did vastly more mental calculation than the guy in the forest. And it's just an ordinary Sunday, a day of leisure instead of my job which is a constant mental challenge, even if somewhat soulless at times.
Hell, even spending time in a large supermarket making permutations of tens of thousands of meals. The average supermarket has 20-40 thousand items. Processing prices versus weight/size/marketing info, is likely a bigger daily mental hurdle than picking grain and grinding it into flower and baking bread and eating that.
Quite a bit, I imagine.
We tend to discount the complexity of tasks we don't have to do. In the same way you dismiss the complexities of living off the land as "sitting in a forest", someone could uncharitably describe your day as "sitting in front of a computer."
Also, be careful not to confuse the importance of the subject matter or tool with the difficulty of the task. Reading about the discovery of Neptune or a political scandal likely requires much less mental activity than identifying an animal by its tracks and then tracking it though a forest.