29 ms·

Researchers find IQ scores dropping since the 1970s

141 points by danielam 8y ago

rossdavidh 8y ago
So, technically, it's only the Norwegians who are getting dumber.
Symmetry 8y ago
When I read this one obvious explanation would be that as parents gets older their gametes accumulate more mutations, especially men, and the children they have later on in life suffer a bit. But that effect should be very small compared to the effect sizes reported here. The bit about fish eating makes me think this might relate to omega-3/omega-6 fat balances in our diets?
- haikuginger 8y ago
  When I read this one obvious explanation would be that IQ tests are designed with biased assumptions based on the cultural environments in which they were designed, and that those biased assumptions become more and more foreign as more generations pass since the test was originally designed. See? I can speculate baselessly too.
  - Symmetry 8y ago
    There's certainly an advantage to taking IQ tests if you come from a culture that values abstract thoughts relatively highly compared to concrete thoughts. This is all based on Norwegian data and if there were some huge cultural shift in Norway I might not know. But usually when you see big changes it's adding iodine to the salt, or lead in the environment, or famines, or disease or something like that. Seriously, iodizing salt added 10 points to the IQs of Americans around the great lakes where iodine deficiency had been a big problem. And generally if it was a matter of shifting cultural environments I'd hope that would be obvious from looking at the subtest scores.
sambe 8y ago
The article: "The researchers also found some differences between family groups, suggesting that some of the decline might be due to environmental factors. But they also suggest that lifestyle changes could account for some of the decline, as well, such as changes in the education system and children reading less and playing video games more. Sadly, other researchers have found similar results." The paper: "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." Is this bad reporting or am I mis-understanding the conclusion of the authors? EDIT: I think I was misunderstanding the conclusion of the authors. They believe they have shown that environmental factors are the main cause (from skimming the full paper's discussion).
- varjag 8y ago
  Sounds like an oblique way to say the upbringing is the problem.
  - pavel_lishin 8y ago
    Sounds like an oblique way to say that IQ tests are aimed at people brought up by the 1960's educational system.
    - Someone1234 8y ago
      I think this quote mirrors your point nicely (on psychometrics): > According to a 2006 article by the National Center for Biotechnology Information, contemporary psychological research often did not reflect substantial recent developments in psychometrics and "bears an uncanny resemblance to the psychometric state of the art as it existed in the 1950s."
      - jabgrabdthrow 8y ago
        What is the current state of the art? I thought it was all progress towards eliminating things that are actually “knowledge” and so look more and more like the abstract IQ tests we see today.
deleted 8y ago
[deleted]
yasp 8y ago
I'm sure I'll be downvoted into oblivion for making the observation but surely this isn't surprising given that people with lower IQs tend to have more babies and have babies earlier in life than do people with higher IQs. [0] [0] https://en.m.wikipedia.org/wiki/Fertility_and_intelligence https://en.m.wikipedia.org/wiki/Fertility_and_intelligence
- vilhelm_s 8y ago
  The main point of the paper being reported on here (http://www.pnas.org/content/early/2018/06/05/1718793115 http://www.pnas.org/content/early/2018/06/05/1718793115) is that this is not the explanation for the Norwegian IQ trends.
- bthrm 8y ago
  That’s what the intro to the movie Idiocracy says :P
  - alpeb 8y ago
    Please don't refer to those as "movies". They're really documentaries, just like Terminator et al.
    - drharby 8y ago
      Humor is frowned upon as a vehicle for dialogue it seems
- Retric 8y ago
  That's a common myth. Higher than average IQ men have significantly more kids it's less significant and possibly negative for women. "More rigorous studies carried out on Americans alive after the Second World War returned different results suggesting a slight positive correlation with respect to intelligence." Critically these children are often had latter in life making studies based on younger age cohorts give different results. Higher education also has a negative impact.
  - 8y ago
bthrm 8y ago
I don’t know about Norway, but here in Spain the % of people who sign up to the military who are immigrants has been steadily increasing these decades, so a drop in IQ does not surprise me at all.
- pavel_lishin 8y ago
  Why would immigrants have a lower IQ than native spaniards? Also, does Spain only administer IQ tests to members of the military? Or are you saying that members of the military have a lower IQ than the rest of the population?
  - bthrm 8y ago
    In TFA it says this drop in IQ was detected because of tests done to people who sign up to the military. I’m talking about how there are more and more immigrants joining the military here as years pass and that if in Norway the same is happening it’s normal that IQ is dropping as I expect immigrants to have a lower IQ than natives.
    - v_lisivka 8y ago
      Immigrants may have lower IQ score because of cultural barrier, e.g. Spanish is foreign language for them, so they will fail association tests.
      - ravar 8y ago
        This language barrier is partially what motivated the development of the Raven progressive matrices test. The test was used by the UK military to judge recruits without creating a bias based off of the recruits language.
    - robin_reala 8y ago
      Why would you expect that?
    - ctrl-j 8y ago
lainon 8y ago
Didn't read the article, but isn't IQ always steady? 100 the average, 130 top 2% etc. Sure intelligence can change, but wouldn't IQ scores adjust to that?
- Nav_Panel 8y ago
  From Wikipedia on the Flynn Effect: "When intelligence quotient (IQ) tests are initially standardized using a sample of test-takers, by convention the average of the test results is set to 100 and their standard deviation is set to 15 or 16 IQ points. When IQ tests are revised, they are again standardized using a new sample of test-takers, usually born more recently than the first. Again, the average result is set to 100. However, when the new test subjects take the older tests, in almost every case their average scores are significantly above 100." I believe the posted study is discussing the reason why this trend of increasing scores might no longer hold.
  - lawlessone 8y ago
    >However, when the new test subjects take the older tests, in almost every case their average scores are significantly above 100." If all these people have tried one IQ test they're likely to perform better on the older tests. just because they have a little more practice.
    - jarfil 8y ago
      Tests are usually not the same, but they are "the same kind", and it is expected that practicing a kind of problem can give an advantage at solving the same kind of problem in the future. It's pretty much a fundamental aspect of learning.
- neolefty 8y ago
  The article doesn't address that, but I have to assume they're talking about non-normalized scores.
- deleted 8y ago
  [deleted]
bloak 8y ago
Rather than claim that "IQ" has fallen they should give some examples of the particular questions which people have got worse at answering correctly, because "IQ" doesn't really exist; all that exists is the normalised score from a particular questionnaire. I took an IQ test once. One of the questions that I couldn't answer was to spot what was missing in a picture. It was the hat band. I can't tell you exactly what kind of hat it was, but it was worn by a man and looked like something I might perhaps see in an old film. One of the questions that I could answer was to spot the odd one out in a list that looked something like: spondee, dactyl, trochee, ... If people have got worse at answering those two questions then I am not surprised.
- dragonwriter 8y ago
  > Rather than claim that "IQ" has fallen they should give some examples of the particular questions which people have got worse at answering correctly, because "IQ" doesn't really exist; all that exists is the normalised score from a particular questionnaire. No, because IQ (as much as any other concept denoted by a label in language) does really exist, and there isn't just a single test (“questionnaire”) for measuring it.
- bakhy 8y ago
  Sounds like a really bad IQ test. I took a Mensa IQ test once, and all the questions were grids, 3x3, with various patterns in all cells except the lower right one, and 6 (I think) offered answer patterns. You pick the one that you think best fits into the overall pattern of the grid. Such a test seems much better to me, since it does not depend on what you know, though I guess even that might have some issues. Many popular IQ tests are really full of trick questions that mostly depend on whether you've seen the trick before...
  - IggleSniggle 8y ago
    Pattern recognition ability is associated with higher false positives. Eg, conspiracy theorists typically perform significantly better on pattern recognition tests. A pattern recognition test is indeed measuring something, but “intelligence quotient” may be a misnomer. Full disclosure: I do very well on pattern recognition tests. I also am often accused of “reinventing the wheel.” I think these are related; but then, I would.
catwell 8y ago
I wondered if it was related to breastfeeding, since it is known to have a positive correlation. It turns out breastfeeding in Norway followed the exact opposite trend: falling from the end of WWI to 1970, and picking up since then ( source: https://www.semanticscholar.org/paper/Donor-milk-banking-and-breastfeeding-in-Norway.-Grøvslien-Grønn/b7e9fe381364dcd8d118cfb5f7988ca60a56f7b8 https://www.semanticscholar.org/paper/Donor-milk-banking-and... )
commandlinefan 8y ago
I can't tell if it's because I'm just getting older or because I'm surrounded by distractions (both electronic and caused by this open office nightmare trend), but my ability to _concentrate_ seems to go down every year. When I was in my 20's, I could focus on a math problem for hours at a time. Now, I need to take a break and look at something else every 10 minutes. Is the world changing to make it harder to accumulate knowledge and improve intelligence?
- neves 8y ago
  Probably both. My problem isn't that it is more difficult to concentrate as I get older, but that I spend more time to get back to a flow state after I'm interrupted.
- weberc2 8y ago
  I think it's the distractions. I'm in my late 20s and when I was in college and didn't have a smart phone, I could hold my focus on a math problem for hours on a time. Now like you, I need to take a break and look at something else every 10 minutes.
- ujal 8y ago
  Perhaps you don't give a f* anymore?
  - debeers 8y ago
    This is incidental, but there are important activities that gotten harded for me in recent years - just as OP described. It's pretty bold to blame just lack of motivation or commitment.
  - cautionarytale 8y ago
    Even if true, that's more of a description than a solution. Generating new f*s to give is a hard problem.
- MisterTea 8y ago
  Life gets in the way. In my late 30's, full time job, side business, and managing properties makes things very difficult. Hobbies take a big back seat to all of that. I only have a few hours every night to tinker with stuff whereas in my 20's I had a single job and no other worries.
axilmar 8y ago
How do these results correlate with the increase/decrease of wages and social services in said country, I wonder.
mendelsd 8y ago
Related: "... data ... from the UK Biobank... suggests genetic contributions to intelligence and educational achievement are currently disfavoured by natural selection". [1] [1] https://www.economist.com/science-and-technology/2017/12/19/data-from-half-a-million-people-show-that-natural-selection-has-not-stopped https://www.economist.com/science-and-technology/2017/12/19/...
bedane 8y ago
Some french scientist makes a compelling case for correlating this drop with the generalization of TV presence in homes. Found him : Michel Desmurget https://www.dailymotion.com/video/xpjec4 https://www.dailymotion.com/video/xpjec4
bitcharmer 8y ago
I know a quite prominent MENSA member and according to him IQ tests are a fundamentally flawed way of measuring intelligence. Not only are there different types of intelligence but more importantly, the current methodology is actually a test of one's ability to solve a very narrow type of puzzles. This can be practised effectively increasing your score significantly. Does becoming good at puzzles mean I got any wiser?
- wenc 8y ago
  As you alluded to in your comment, there are different types of intelligence. Also, the concept of intelligence itself is too broad to define precisely. That said, IQ tests are not as flawed as people think -- they measure a particular set of abilities, and there is evidence that those abilities correlate to aptitudes that are useful in some areas of life. For instance, the Advanced Raven Matrices test (a "culture-free" test used by Mensa and other organizations) measures visual-spatial skills and does it fairly well at that (as long as it is not gamed -- it is possible to study for an IQ test and do well in it -- but then again any test can be gamed). If a particular task/job requires heavy visual-spatial skills, chances are that people who score well on visual-spatial tests will tend to do well there. Visual-spatial skills are a type of intelligence. It's not the only type, but it is one type. You need to understand what the test is measuring.
- dionidium 8y ago
  I'm not an expert in the field, but my casual understanding is that the research shows basically the opposite to be true. That is to say that IQ is generally predictive of success and/or ability across just about any dimension you want to choose. Said another way, if you had to hire somebody sight-unseen and you were only allowed to know one piece of information about them, IQ would be the strongest predictor of performance. (I want to be very clear: that's not to say that the person with the highest IQ will always be the best performer; it's just to say that if you had no other information, and you had to hire based on just one piece of information, IQ would be your best bet.)
  - Scea91 8y ago
    You would have to define more formally what you mean by one piece of information and even then I think there are counterexamples to your argument. For example, If I wanted to hire a doctor I would prefer to know if the applicant had medical degree over their IQ.
eruci 8y ago
I feel much dumber now in my 40s as opposed to my 20s. I pretty much stopped reading books after high school and am no longer able to solve certain math problems. Instead, I read stuff like this article.
- tonyedgecombe 8y ago
  I went the opposite way, I didn’t graduate until I was nearly fifty.
disgruntledphd2 8y ago
This is an interesting study. It is worth noting that the recent meta-analysis (https://www.ncbi.nlm.nih.gov/pubmed/24979188 https://www.ncbi.nlm.nih.gov/pubmed/24979188) showed no such effect across a wide variety of scales and countries. However, the really interesting question here (which is possible to answer because of the size and sampling of the Norwegian data) is what is happening in Norway, for this effect to be occurring in what appears like a consistent fashion? In other words, we should in general rely on meta-analyses rather than individual studies when looking at results like these.
- vilhelm_s 8y ago
  Good comment! The paper you link also specifically mentions the results from Scandinavia: > Our study did not find evidence for the plateauing or decline of the Flynn effect in the United States, as has been documented in Norway (Sundet et al., 2004) and Denmark (Teasdale & Owen, 2008; Teasdale & Owen, 2005), respectively. Table 5.6 in the WAIS-IV manual (Wechsler, 2008) summarizes an excellent planned comparison of the WAIS-III (standardized in 1995) and the WAIS-IV (standardized in 2005) scores administered in counterbalanced order to 240 examinees. This table shows results similar to our meta-analysis, with average WAIS-III scores about 3 points higher than WAIS-IV scores. In addition, the effect was similar across age and ability level cohorts. To the extent that the United States and Scandinavia differ on at least the variables proposed to be related to the plateauing of scores in Scandinavia (e.g., family life factors [Sundet et al., 2004] and educational priorities [Teasdale & Owen, 2008; Teasdale & Owen, 2005]), we might anticipate the difference in IQ score patterns noted. For example, Scandinavia’s parental leave and subsidized childcare might be indices of optimal socioenvironmental conditions and are generous relative to the United States.
swoongoonz 8y ago
I distinctly remember a professor in college saying that he felt like the caliber of students enrolling every year declines. I was kind of offended, but hey maybe we was right.
- curtis 8y ago
  A much larger number of people attend college today than in the past. Since most of the smartest people were probably already going to college, increasing the size of the pool would almost certainly decrease the "average smartness" of college students. Alternatively, you could just say that historically college students were disproportionately the "best students" during primary education, and increasing the size of the pool would result in more people who were not as good students attending college.
- asdsa5325 8y ago
  Unsurprising, since more people attend college in proportion to the population size. The more people that attend, the closer to average that the caliber approaches.
learc83 8y ago
This test was done for people being examined for military service. It looks like Norway doesn't force military service, but does force people to be examined. Perhaps people just take a mandatory military exam less seriously than they did during the cold war. Also the culture of Norway is much less homogeneous than it was in the 70s and it's impossible to completely remove cultural biases from IQ tests--not to mention far more people who don't speak the language natively.
teilo 8y ago
Could this also explain why Mensa's admission standards have been watered down in recent years? I mean, on paper, they are still the same, but in practice - not so much.
- paulie_a 8y ago
  Personally I negatively judge members of Mensa.
  - astrodust 8y ago
    Anyone who pays an annual fee to prove they're smart... It's like selling an "elevator pass". Too easy.
    - teilo 8y ago
      Easy has nothing to do with it. It's not like you have to renew an IQ test. You either passed it, or you didn't. An expired membership card proves they passed a proctored test just as well as an active membership does. In any case, I agree with you in spirit. It's just bragging rights. I think a lot of people renew just so they can say they are a member. But that's stupid. It proves nothing. Nobody else cares. Nobody else is impressed. Want to show yourself to truly be an ass? Pull out your Mensa card. I truly don't give a f*ck. I was in for one year. Their journal and discounts were not worth the price of membership. I already have friends and don't need any more. It would have been a waste of money to renew.
    - beenBoutIT 8y ago
      Anyone who is concerned about being smart isn't operating on a level that I would consider "gifted".
- paulpauper 8y ago
  the opposite actually. by not allowing SAT scores, they made it harder
lawlessone 8y ago
Couldn't have anything to do with all the extra carbon dioxide in the air could it?
- mac01021 8y ago
  I don't think there is any reason to suspect that over a hundred other causes: Radiation from cell phones Increased screen time for children More pesticides in our diets The fact that we have to think about a greater variety of things through the course of a day has caused our brains to structure themselves for better context-switching at the expense of a little bit of focus et cetera
SCAQTony 8y ago
Perhaps the most logical explanation is that people don't have to be as smart as they were when computers, the internet and DIY "recipes" are so readily available. Even using a paper map is obsolete when a smart phone can verbally direct you. How many people do math by hand now? Example: California native Americans (Chumash) did not have to be smart. Every day was a great day, food and water were everywhere from the ocean to the valleys whereas in south America things were more difficult. Spaniards were stunned by the Aztec capital being larger and more advanced than anything in Europe. The Aztecs had astronomy, math, and domesticated turkeys for food. They created all that because they had too. Food in Mesoamerica: http://tlmorganfield.com/food-mesoamerica-domesticated-food-animals/ http://tlmorganfield.com/food-mesoamerica-domesticated-food-... Aztec capital, Tenochtitlan: https://www.livescience.com/34660-tenochtitlan.html https://www.livescience.com/34660-tenochtitlan.html
- ekianjo 8y ago
  > Even using a paper map is obsolete when a smart phone can verbally direct you. How many people do math by hand now? hardly convincing since IQ tests usually don't depend on your level of training or knowledge.
  - learc83 8y ago
    They try not to, but trying isn't the same thing as succeeding. IQ tests have documented cultural biases, and we know that you can study and prepare for IQ tests to improve your score.
classicsnoot 8y ago
Why is every post asking questions WRT the effects of gender and migration being caveated so dramatically? It would appear people are afraid to even ask about what seem to be obvious relevant factors. There are noticable differences in the IQ averages between gender groups as well as origin, but the plasticity of IQ has also been established. The fear of reprisal and condemnation for wrongthink is starting to resemble Puritan New England. I sincerely hope we don't start burning witches...
- alexandercrohde 8y ago
  Migration is a totally reasonable candidate, but if I imagine you're getting downvoted for how you're expressing yourself (i.e. very emotional) rather than what you're saying.
  - classicsnoot 8y ago
    When reason fails, emotions rise, but I take your point and appreciate your reproof.
- rjsw 8y ago
  I can think of alternative explanations for several taboo topics.
  - classicsnoot 8y ago
    I'd like to hear them, if you are still willing to share.
startupdiscuss 8y ago
Check the amount of sleep they get!
jibjib 8y ago
First time comment here; felt compelled after reading some of the comments. Please make sure you all pay attention to your physical state while trying to concentrate etc (for the people who’ve been seeing dips in performance and/or getting “in zone”). Only yesterday I noticed that I had somehow formed the habit of holding my breath when reading/learning/absorbing anything complex. Seems pretty ridiculous but I went from having a hard time understanding some high mathematics to - when regulating breath appropriately - breezing through.
pfschell 8y ago
Looks like they ignored the national origin of the people tested. Norwegian IQs didn't drop. The average population of people living in Norway dropped. The first chart in this link shows why: https://www.ssb.no/en/befolkning/statistikker/innvbef/arkiv/2010-04-29 https://www.ssb.no/en/befolkning/statistikker/innvbef/arkiv/...
- IkmoIkmo 8y ago
  > Using administrative register data and cognitive ability scores from military conscription data covering three decades of Norwegian birth cohorts (1962–1991) Doesn't seem as if immigration played any role in this study.
danielam 8y ago
I am reminded of a quotation from the first chapter [0] of McLuhan's "Understanding Media": "It is in our I.Q. testing that we have produced the greatest flood of misbegotten standards. Unaware of our typographic cultural bias, our testers assume that uniform and continuous habits are a sign of intelligence, thus eliminating the ear man and the tactile man." If IQ tests make tacit assumptions of this kind, could the shift in the dominant media forms be playing a role? [0] http://web.mit.edu/allanmc/www/mcluhan.mediummessage.pdf http://web.mit.edu/allanmc/www/mcluhan.mediummessage.pdf
jeandejean 8y ago
It's hard to believe, I've read rather the opposite for quite a while, especially recently with Enlightement Now from Steven Pinker. I should get those references!
- philipkglass 8y ago
  Enlightenment Now highlights world-scale trends. This study highlights Norwegian trends. It is possible -- even likely -- that some small subgroups will exhibit trends that don't match the larger global trend. Norway's population is only 0.005 billion out of a world population of 7.6 billion. As another example, it is simultaneously true that world manufacturing output kept increasing even as Michigan's manufacturing diminished. There's no contradiction between those two facts.
  - jeandejean 8y ago
    I understand your point. However, in Enlightenment Now, you see patterns that are similar in all countries, especially Western countries. A country like Norway going backward is very unlikely, especially on a sustained manner over decades, no matter small the country is.
swebs 8y ago
The same results were also observed in Denmark in 2007. http://www.iapsych.com/iqmr/fe/LinkedDocuments/teasdale2008.pdf http://www.iapsych.com/iqmr/fe/LinkedDocuments/teasdale2008....
josephdviviano 8y ago
Is it possible that the kinds of people military entering service has changed over the years in Norway? I haven't searched very hard, but it isn't clear how the conscription/selection criteria has evolved over the years. These would be very hard variables to properly control for.
- audunw 8y ago
  Good point. Used to be mandatory, now it’s not. I know it’s quite common among those going for higher education to avoid it
- vilhelm_s 8y ago
  Note that the intelligence tests are for people who are evaluated for conscription, not the ones who are finally conscripted, so they cover a large fraction of the population (80%-90% of males). Since not everyone was given the test, there are indeed large selection effects. The main technical contribution of the paper we are discussing (http://www.pnas.org/content/early/2018/06/05/1718793115 http://www.pnas.org/content/early/2018/06/05/1718793115) is to try to estimate what the selection effect is. They use a comparison of siblings. By comparing the score of brothers who were both given the test, one can can create a model to estimate the score of one brother from the score of the other. Then by comparing families where one brother was given the test and the other was not, one can estimate how the the probablility of the test board administering the test depends on the IQ of the testee. Then given that curve, one can estimate the average IQ of the entire population from the available test scores. Their result is that selection bias hides some of the effect. That is, as the Norwegian military got smaller, the selection board got pickier and tested fewer (smarter) people, so if you just look at the average score you will not see the full drop.
jeffreyrogers 8y ago
The most important part of the abstract is this: > 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. My first thought was the decline might be due to rising number of immigrants, but this suggests that is not true. Instead it appears the decline is due to some broader environmental factor that is common across all families. It also suggests that this is likely occurring in the rest of the developed world as well, since I can't think of anything obvious that's occurring in Norway that isn't also occurring in the rest of the developed world.
cerealbad 8y ago
the internet is quite addictive, the trick is to be a high functioning addict. you'll be dumber, but all the richer for it.
JoeAltmaier 8y ago
An oblique comment in the article about changing childhood behaviors - more video games and less book reading - was quite telling. Is the population simply culturally drifting 'out from under' the norm for the test? Perhaps they could ask more video-game-related questions, and renormalize. "Which NPC is likely to give you a quest?" kind of thing.
BloodyHands 8y ago
IQ and depression are both tools of Colonialism. They are not relevant to the real world outside Colonialism.
- pokemongoaway 8y ago
  IQ isn't the only or best way to judge someone, but what are you even saying? That attempting to measure intelligence is the same as colonialism? Who is being colonized here? Also who are the IQ winners (Asians) accused of colonizing?
- danmg 8y ago
  IQ is a way of forecasting the best possible future outcomes in children. For adults, look at what they've done.
- asdsa5325 8y ago
  What the hell is wrong with you?
  - mythrwy 8y ago
    Colonialism?
murph-almighty 8y ago
This is mostly irrelevant- I feel as though the phrase IQ has become so diluted by jackasses on social media who feel a need to brag about their IQ. Usually they got the results from some snake-oily trivia site. Because of this, that whenever I see a study that mentions IQ I immediately doubt it. What is a standard IQ test? What does it test for?
- deleted 8y ago
  [deleted]
ujal 8y ago
I will probably never understand IQ and its purpose for real life problems. It is either me who doesn't get it or all the people out there who lack introspection to understand what exactly it was that enabled them to grasp some new concept.
fejfieji 8y ago
This is logically impossible for the population as a whole, because IQ is defined as a relative metric. I.e. an IQ of 100 is (ideally) equal to whatever the current median intelligence is. It sounds like Norway's national service is just getting dumber by comparison.
marojejian 8y ago
The original article, btw: https://sci-hub.tw/http://www.pnas.org/content/early/2018/06/05/1718793115 https://sci-hub.tw/http://www.pnas.org/content/early/2018/06...
known 8y ago
The more testosterone a man has, the less likely he is to hang around to help bring up baby http://www.economist.com/news/science-and-technology/21679772-changes-mans-testosterone-level-show-kind-parent-he-will-be-pot-luck http://www.economist.com/news/science-and-technology/2167977...

141 points by danielam 8y ago

So, technically, it's only the Norwegians who are getting dumber.

When I read this one obvious explanation would be that as parents gets older their gametes accumulate more mutations, especially men, and the children they have later on in life suffer a bit. But that effect should be very small compared to the effect sizes reported here. The bit about fish eating makes me think this might relate to omega-3/omega-6 fat balances in our diets?

haikuginger 8y ago
When I read this one obvious explanation would be that IQ tests are designed with biased assumptions based on the cultural environments in which they were designed, and that those biased assumptions become more and more foreign as more generations pass since the test was originally designed. See? I can speculate baselessly too.
- Symmetry 8y ago
  There's certainly an advantage to taking IQ tests if you come from a culture that values abstract thoughts relatively highly compared to concrete thoughts. This is all based on Norwegian data and if there were some huge cultural shift in Norway I might not know. But usually when you see big changes it's adding iodine to the salt, or lead in the environment, or famines, or disease or something like that. Seriously, iodizing salt added 10 points to the IQs of Americans around the great lakes where iodine deficiency had been a big problem. And generally if it was a matter of shifting cultural environments I'd hope that would be obvious from looking at the subtest scores.

sambe 8y ago

The article: "The researchers also found some differences between family groups, suggesting that some of the decline might be due to environmental factors. But they also suggest that lifestyle changes could account for some of the decline, as well, such as changes in the education system and children reading less and playing video games more. Sadly, other researchers have found similar results." The paper: "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." Is this bad reporting or am I mis-understanding the conclusion of the authors? EDIT: I think I was misunderstanding the conclusion of the authors. They believe they have shown that environmental factors are the main cause (from skimming the full paper's discussion).

varjag 8y ago
Sounds like an oblique way to say the upbringing is the problem.
- pavel_lishin 8y ago
  Sounds like an oblique way to say that IQ tests are aimed at people brought up by the 1960's educational system.
  - Someone1234 8y ago
    I think this quote mirrors your point nicely (on psychometrics): > According to a 2006 article by the National Center for Biotechnology Information, contemporary psychological research often did not reflect substantial recent developments in psychometrics and "bears an uncanny resemblance to the psychometric state of the art as it existed in the 1950s."
    - jabgrabdthrow 8y ago
      What is the current state of the art? I thought it was all progress towards eliminating things that are actually “knowledge” and so look more and more like the abstract IQ tests we see today.

deleted 8y ago

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yasp 8y ago

I'm sure I'll be downvoted into oblivion for making the observation but surely this isn't surprising given that people with lower IQs tend to have more babies and have babies earlier in life than do people with higher IQs. [0] [0] https://en.m.wikipedia.org/wiki/Fertility_and_intelligence https://en.m.wikipedia.org/wiki/Fertility_and_intelligence

vilhelm_s 8y ago
The main point of the paper being reported on here (http://www.pnas.org/content/early/2018/06/05/1718793115 http://www.pnas.org/content/early/2018/06/05/1718793115) is that this is not the explanation for the Norwegian IQ trends.
bthrm 8y ago
That’s what the intro to the movie Idiocracy says :P
- alpeb 8y ago
  Please don't refer to those as "movies". They're really documentaries, just like Terminator et al.
  - drharby 8y ago
    Humor is frowned upon as a vehicle for dialogue it seems
Retric 8y ago
That's a common myth. Higher than average IQ men have significantly more kids it's less significant and possibly negative for women. "More rigorous studies carried out on Americans alive after the Second World War returned different results suggesting a slight positive correlation with respect to intelligence." Critically these children are often had latter in life making studies based on younger age cohorts give different results. Higher education also has a negative impact.
- 8y ago

bthrm 8y ago

I don’t know about Norway, but here in Spain the % of people who sign up to the military who are immigrants has been steadily increasing these decades, so a drop in IQ does not surprise me at all.

pavel_lishin 8y ago
Why would immigrants have a lower IQ than native spaniards? Also, does Spain only administer IQ tests to members of the military? Or are you saying that members of the military have a lower IQ than the rest of the population?
- bthrm 8y ago
  In TFA it says this drop in IQ was detected because of tests done to people who sign up to the military. I’m talking about how there are more and more immigrants joining the military here as years pass and that if in Norway the same is happening it’s normal that IQ is dropping as I expect immigrants to have a lower IQ than natives.
  - v_lisivka 8y ago
    Immigrants may have lower IQ score because of cultural barrier, e.g. Spanish is foreign language for them, so they will fail association tests.
    - ravar 8y ago
      This language barrier is partially what motivated the development of the Raven progressive matrices test. The test was used by the UK military to judge recruits without creating a bias based off of the recruits language.
  - robin_reala 8y ago
    Why would you expect that?
  - ctrl-j 8y ago

lainon 8y ago

Didn't read the article, but isn't IQ always steady? 100 the average, 130 top 2% etc. Sure intelligence can change, but wouldn't IQ scores adjust to that?

Nav_Panel 8y ago
From Wikipedia on the Flynn Effect: "When intelligence quotient (IQ) tests are initially standardized using a sample of test-takers, by convention the average of the test results is set to 100 and their standard deviation is set to 15 or 16 IQ points. When IQ tests are revised, they are again standardized using a new sample of test-takers, usually born more recently than the first. Again, the average result is set to 100. However, when the new test subjects take the older tests, in almost every case their average scores are significantly above 100." I believe the posted study is discussing the reason why this trend of increasing scores might no longer hold.
- lawlessone 8y ago
  >However, when the new test subjects take the older tests, in almost every case their average scores are significantly above 100." If all these people have tried one IQ test they're likely to perform better on the older tests. just because they have a little more practice.
  - jarfil 8y ago
    Tests are usually not the same, but they are "the same kind", and it is expected that practicing a kind of problem can give an advantage at solving the same kind of problem in the future. It's pretty much a fundamental aspect of learning.
neolefty 8y ago
The article doesn't address that, but I have to assume they're talking about non-normalized scores.
deleted 8y ago
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bloak 8y ago

Rather than claim that "IQ" has fallen they should give some examples of the particular questions which people have got worse at answering correctly, because "IQ" doesn't really exist; all that exists is the normalised score from a particular questionnaire. I took an IQ test once. One of the questions that I couldn't answer was to spot what was missing in a picture. It was the hat band. I can't tell you exactly what kind of hat it was, but it was worn by a man and looked like something I might perhaps see in an old film. One of the questions that I could answer was to spot the odd one out in a list that looked something like: spondee, dactyl, trochee, ... If people have got worse at answering those two questions then I am not surprised.

dragonwriter 8y ago
> Rather than claim that "IQ" has fallen they should give some examples of the particular questions which people have got worse at answering correctly, because "IQ" doesn't really exist; all that exists is the normalised score from a particular questionnaire. No, because IQ (as much as any other concept denoted by a label in language) does really exist, and there isn't just a single test (“questionnaire”) for measuring it.
bakhy 8y ago
Sounds like a really bad IQ test. I took a Mensa IQ test once, and all the questions were grids, 3x3, with various patterns in all cells except the lower right one, and 6 (I think) offered answer patterns. You pick the one that you think best fits into the overall pattern of the grid. Such a test seems much better to me, since it does not depend on what you know, though I guess even that might have some issues. Many popular IQ tests are really full of trick questions that mostly depend on whether you've seen the trick before...
- IggleSniggle 8y ago
  Pattern recognition ability is associated with higher false positives. Eg, conspiracy theorists typically perform significantly better on pattern recognition tests. A pattern recognition test is indeed measuring something, but “intelligence quotient” may be a misnomer. Full disclosure: I do very well on pattern recognition tests. I also am often accused of “reinventing the wheel.” I think these are related; but then, I would.

catwell 8y ago

I wondered if it was related to breastfeeding, since it is known to have a positive correlation. It turns out breastfeeding in Norway followed the exact opposite trend: falling from the end of WWI to 1970, and picking up since then ( source: https://www.semanticscholar.org/paper/Donor-milk-banking-and-breastfeeding-in-Norway.-Grøvslien-Grønn/b7e9fe381364dcd8d118cfb5f7988ca60a56f7b8 https://www.semanticscholar.org/paper/Donor-milk-banking-and... )

commandlinefan 8y ago

I can't tell if it's because I'm just getting older or because I'm surrounded by distractions (both electronic and caused by this open office nightmare trend), but my ability to _concentrate_ seems to go down every year. When I was in my 20's, I could focus on a math problem for hours at a time. Now, I need to take a break and look at something else every 10 minutes. Is the world changing to make it harder to accumulate knowledge and improve intelligence?

neves 8y ago
Probably both. My problem isn't that it is more difficult to concentrate as I get older, but that I spend more time to get back to a flow state after I'm interrupted.
weberc2 8y ago
I think it's the distractions. I'm in my late 20s and when I was in college and didn't have a smart phone, I could hold my focus on a math problem for hours on a time. Now like you, I need to take a break and look at something else every 10 minutes.
ujal 8y ago
Perhaps you don't give a f* anymore?
- debeers 8y ago
  This is incidental, but there are important activities that gotten harded for me in recent years - just as OP described. It's pretty bold to blame just lack of motivation or commitment.
- cautionarytale 8y ago
  Even if true, that's more of a description than a solution. Generating new f*s to give is a hard problem.
MisterTea 8y ago
Life gets in the way. In my late 30's, full time job, side business, and managing properties makes things very difficult. Hobbies take a big back seat to all of that. I only have a few hours every night to tinker with stuff whereas in my 20's I had a single job and no other worries.

axilmar 8y ago

How do these results correlate with the increase/decrease of wages and social services in said country, I wonder.

mendelsd 8y ago

Related: "... data ... from the UK Biobank... suggests genetic contributions to intelligence and educational achievement are currently disfavoured by natural selection". [1] [1] https://www.economist.com/science-and-technology/2017/12/19/data-from-half-a-million-people-show-that-natural-selection-has-not-stopped https://www.economist.com/science-and-technology/2017/12/19/...

bedane 8y ago

Some french scientist makes a compelling case for correlating this drop with the generalization of TV presence in homes. Found him : Michel Desmurget https://www.dailymotion.com/video/xpjec4 https://www.dailymotion.com/video/xpjec4

bitcharmer 8y ago

I know a quite prominent MENSA member and according to him IQ tests are a fundamentally flawed way of measuring intelligence. Not only are there different types of intelligence but more importantly, the current methodology is actually a test of one's ability to solve a very narrow type of puzzles. This can be practised effectively increasing your score significantly. Does becoming good at puzzles mean I got any wiser?

wenc 8y ago
As you alluded to in your comment, there are different types of intelligence. Also, the concept of intelligence itself is too broad to define precisely. That said, IQ tests are not as flawed as people think -- they measure a particular set of abilities, and there is evidence that those abilities correlate to aptitudes that are useful in some areas of life. For instance, the Advanced Raven Matrices test (a "culture-free" test used by Mensa and other organizations) measures visual-spatial skills and does it fairly well at that (as long as it is not gamed -- it is possible to study for an IQ test and do well in it -- but then again any test can be gamed). If a particular task/job requires heavy visual-spatial skills, chances are that people who score well on visual-spatial tests will tend to do well there. Visual-spatial skills are a type of intelligence. It's not the only type, but it is one type. You need to understand what the test is measuring.
dionidium 8y ago
I'm not an expert in the field, but my casual understanding is that the research shows basically the opposite to be true. That is to say that IQ is generally predictive of success and/or ability across just about any dimension you want to choose. Said another way, if you had to hire somebody sight-unseen and you were only allowed to know one piece of information about them, IQ would be the strongest predictor of performance. (I want to be very clear: that's not to say that the person with the highest IQ will always be the best performer; it's just to say that if you had no other information, and you had to hire based on just one piece of information, IQ would be your best bet.)
- Scea91 8y ago
  You would have to define more formally what you mean by one piece of information and even then I think there are counterexamples to your argument. For example, If I wanted to hire a doctor I would prefer to know if the applicant had medical degree over their IQ.

eruci 8y ago

I feel much dumber now in my 40s as opposed to my 20s. I pretty much stopped reading books after high school and am no longer able to solve certain math problems. Instead, I read stuff like this article.

tonyedgecombe 8y ago
I went the opposite way, I didn’t graduate until I was nearly fifty.

disgruntledphd2 8y ago

This is an interesting study. It is worth noting that the recent meta-analysis (https://www.ncbi.nlm.nih.gov/pubmed/24979188 https://www.ncbi.nlm.nih.gov/pubmed/24979188) showed no such effect across a wide variety of scales and countries. However, the really interesting question here (which is possible to answer because of the size and sampling of the Norwegian data) is what is happening in Norway, for this effect to be occurring in what appears like a consistent fashion? In other words, we should in general rely on meta-analyses rather than individual studies when looking at results like these.

vilhelm_s 8y ago
Good comment! The paper you link also specifically mentions the results from Scandinavia: > Our study did not find evidence for the plateauing or decline of the Flynn effect in the United States, as has been documented in Norway (Sundet et al., 2004) and Denmark (Teasdale & Owen, 2008; Teasdale & Owen, 2005), respectively. Table 5.6 in the WAIS-IV manual (Wechsler, 2008) summarizes an excellent planned comparison of the WAIS-III (standardized in 1995) and the WAIS-IV (standardized in 2005) scores administered in counterbalanced order to 240 examinees. This table shows results similar to our meta-analysis, with average WAIS-III scores about 3 points higher than WAIS-IV scores. In addition, the effect was similar across age and ability level cohorts. To the extent that the United States and Scandinavia differ on at least the variables proposed to be related to the plateauing of scores in Scandinavia (e.g., family life factors [Sundet et al., 2004] and educational priorities [Teasdale & Owen, 2008; Teasdale & Owen, 2005]), we might anticipate the difference in IQ score patterns noted. For example, Scandinavia’s parental leave and subsidized childcare might be indices of optimal socioenvironmental conditions and are generous relative to the United States.

swoongoonz 8y ago

I distinctly remember a professor in college saying that he felt like the caliber of students enrolling every year declines. I was kind of offended, but hey maybe we was right.

curtis 8y ago
A much larger number of people attend college today than in the past. Since most of the smartest people were probably already going to college, increasing the size of the pool would almost certainly decrease the "average smartness" of college students. Alternatively, you could just say that historically college students were disproportionately the "best students" during primary education, and increasing the size of the pool would result in more people who were not as good students attending college.
asdsa5325 8y ago
Unsurprising, since more people attend college in proportion to the population size. The more people that attend, the closer to average that the caliber approaches.

learc83 8y ago

This test was done for people being examined for military service. It looks like Norway doesn't force military service, but does force people to be examined. Perhaps people just take a mandatory military exam less seriously than they did during the cold war. Also the culture of Norway is much less homogeneous than it was in the 70s and it's impossible to completely remove cultural biases from IQ tests--not to mention far more people who don't speak the language natively.

teilo 8y ago

Could this also explain why Mensa's admission standards have been watered down in recent years? I mean, on paper, they are still the same, but in practice - not so much.

paulie_a 8y ago
Personally I negatively judge members of Mensa.
- astrodust 8y ago
  Anyone who pays an annual fee to prove they're smart... It's like selling an "elevator pass". Too easy.
  - teilo 8y ago
    Easy has nothing to do with it. It's not like you have to renew an IQ test. You either passed it, or you didn't. An expired membership card proves they passed a proctored test just as well as an active membership does. In any case, I agree with you in spirit. It's just bragging rights. I think a lot of people renew just so they can say they are a member. But that's stupid. It proves nothing. Nobody else cares. Nobody else is impressed. Want to show yourself to truly be an ass? Pull out your Mensa card. I truly don't give a f*ck. I was in for one year. Their journal and discounts were not worth the price of membership. I already have friends and don't need any more. It would have been a waste of money to renew.
  - beenBoutIT 8y ago
    Anyone who is concerned about being smart isn't operating on a level that I would consider "gifted".
paulpauper 8y ago
the opposite actually. by not allowing SAT scores, they made it harder

lawlessone 8y ago

Couldn't have anything to do with all the extra carbon dioxide in the air could it?

mac01021 8y ago
I don't think there is any reason to suspect that over a hundred other causes: Radiation from cell phones Increased screen time for children More pesticides in our diets The fact that we have to think about a greater variety of things through the course of a day has caused our brains to structure themselves for better context-switching at the expense of a little bit of focus et cetera

SCAQTony 8y ago

Perhaps the most logical explanation is that people don't have to be as smart as they were when computers, the internet and DIY "recipes" are so readily available. Even using a paper map is obsolete when a smart phone can verbally direct you. How many people do math by hand now? Example: California native Americans (Chumash) did not have to be smart. Every day was a great day, food and water were everywhere from the ocean to the valleys whereas in south America things were more difficult. Spaniards were stunned by the Aztec capital being larger and more advanced than anything in Europe. The Aztecs had astronomy, math, and domesticated turkeys for food. They created all that because they had too. Food in Mesoamerica: http://tlmorganfield.com/food-mesoamerica-domesticated-food-animals/ http://tlmorganfield.com/food-mesoamerica-domesticated-food-... Aztec capital, Tenochtitlan: https://www.livescience.com/34660-tenochtitlan.html https://www.livescience.com/34660-tenochtitlan.html

ekianjo 8y ago
> Even using a paper map is obsolete when a smart phone can verbally direct you. How many people do math by hand now? hardly convincing since IQ tests usually don't depend on your level of training or knowledge.
- learc83 8y ago
  They try not to, but trying isn't the same thing as succeeding. IQ tests have documented cultural biases, and we know that you can study and prepare for IQ tests to improve your score.

classicsnoot 8y ago

Why is every post asking questions WRT the effects of gender and migration being caveated so dramatically? It would appear people are afraid to even ask about what seem to be obvious relevant factors. There are noticable differences in the IQ averages between gender groups as well as origin, but the plasticity of IQ has also been established. The fear of reprisal and condemnation for wrongthink is starting to resemble Puritan New England. I sincerely hope we don't start burning witches...

alexandercrohde 8y ago
Migration is a totally reasonable candidate, but if I imagine you're getting downvoted for how you're expressing yourself (i.e. very emotional) rather than what you're saying.
- classicsnoot 8y ago
  When reason fails, emotions rise, but I take your point and appreciate your reproof.
rjsw 8y ago
I can think of alternative explanations for several taboo topics.
- classicsnoot 8y ago
  I'd like to hear them, if you are still willing to share.

startupdiscuss 8y ago

Check the amount of sleep they get!

jibjib 8y ago

First time comment here; felt compelled after reading some of the comments. Please make sure you all pay attention to your physical state while trying to concentrate etc (for the people who’ve been seeing dips in performance and/or getting “in zone”). Only yesterday I noticed that I had somehow formed the habit of holding my breath when reading/learning/absorbing anything complex. Seems pretty ridiculous but I went from having a hard time understanding some high mathematics to - when regulating breath appropriately - breezing through.

pfschell 8y ago

Looks like they ignored the national origin of the people tested. Norwegian IQs didn't drop. The average population of people living in Norway dropped. The first chart in this link shows why: https://www.ssb.no/en/befolkning/statistikker/innvbef/arkiv/2010-04-29 https://www.ssb.no/en/befolkning/statistikker/innvbef/arkiv/...

IkmoIkmo 8y ago
> Using administrative register data and cognitive ability scores from military conscription data covering three decades of Norwegian birth cohorts (1962–1991) Doesn't seem as if immigration played any role in this study.

danielam 8y ago

I am reminded of a quotation from the first chapter [0] of McLuhan's "Understanding Media": "It is in our I.Q. testing that we have produced the greatest flood of misbegotten standards. Unaware of our typographic cultural bias, our testers assume that uniform and continuous habits are a sign of intelligence, thus eliminating the ear man and the tactile man." If IQ tests make tacit assumptions of this kind, could the shift in the dominant media forms be playing a role? [0] http://web.mit.edu/allanmc/www/mcluhan.mediummessage.pdf http://web.mit.edu/allanmc/www/mcluhan.mediummessage.pdf

jeandejean 8y ago

It's hard to believe, I've read rather the opposite for quite a while, especially recently with Enlightement Now from Steven Pinker. I should get those references!

philipkglass 8y ago
Enlightenment Now highlights world-scale trends. This study highlights Norwegian trends. It is possible -- even likely -- that some small subgroups will exhibit trends that don't match the larger global trend. Norway's population is only 0.005 billion out of a world population of 7.6 billion. As another example, it is simultaneously true that world manufacturing output kept increasing even as Michigan's manufacturing diminished. There's no contradiction between those two facts.
- jeandejean 8y ago
  I understand your point. However, in Enlightenment Now, you see patterns that are similar in all countries, especially Western countries. A country like Norway going backward is very unlikely, especially on a sustained manner over decades, no matter small the country is.

swebs 8y ago

The same results were also observed in Denmark in 2007. http://www.iapsych.com/iqmr/fe/LinkedDocuments/teasdale2008.pdf http://www.iapsych.com/iqmr/fe/LinkedDocuments/teasdale2008....

josephdviviano 8y ago

Is it possible that the kinds of people military entering service has changed over the years in Norway? I haven't searched very hard, but it isn't clear how the conscription/selection criteria has evolved over the years. These would be very hard variables to properly control for.

audunw 8y ago
Good point. Used to be mandatory, now it’s not. I know it’s quite common among those going for higher education to avoid it
vilhelm_s 8y ago
Note that the intelligence tests are for people who are evaluated for conscription, not the ones who are finally conscripted, so they cover a large fraction of the population (80%-90% of males). Since not everyone was given the test, there are indeed large selection effects. The main technical contribution of the paper we are discussing (http://www.pnas.org/content/early/2018/06/05/1718793115 http://www.pnas.org/content/early/2018/06/05/1718793115) is to try to estimate what the selection effect is. They use a comparison of siblings. By comparing the score of brothers who were both given the test, one can can create a model to estimate the score of one brother from the score of the other. Then by comparing families where one brother was given the test and the other was not, one can estimate how the the probablility of the test board administering the test depends on the IQ of the testee. Then given that curve, one can estimate the average IQ of the entire population from the available test scores. Their result is that selection bias hides some of the effect. That is, as the Norwegian military got smaller, the selection board got pickier and tested fewer (smarter) people, so if you just look at the average score you will not see the full drop.

jeffreyrogers 8y ago

The most important part of the abstract is this: > 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. My first thought was the decline might be due to rising number of immigrants, but this suggests that is not true. Instead it appears the decline is due to some broader environmental factor that is common across all families. It also suggests that this is likely occurring in the rest of the developed world as well, since I can't think of anything obvious that's occurring in Norway that isn't also occurring in the rest of the developed world.

cerealbad 8y ago

the internet is quite addictive, the trick is to be a high functioning addict. you'll be dumber, but all the richer for it.

JoeAltmaier 8y ago

An oblique comment in the article about changing childhood behaviors - more video games and less book reading - was quite telling. Is the population simply culturally drifting 'out from under' the norm for the test? Perhaps they could ask more video-game-related questions, and renormalize. "Which NPC is likely to give you a quest?" kind of thing.

BloodyHands 8y ago

IQ and depression are both tools of Colonialism. They are not relevant to the real world outside Colonialism.

pokemongoaway 8y ago
IQ isn't the only or best way to judge someone, but what are you even saying? That attempting to measure intelligence is the same as colonialism? Who is being colonized here? Also who are the IQ winners (Asians) accused of colonizing?
danmg 8y ago
IQ is a way of forecasting the best possible future outcomes in children. For adults, look at what they've done.
asdsa5325 8y ago
What the hell is wrong with you?
- mythrwy 8y ago
  Colonialism?

murph-almighty 8y ago

This is mostly irrelevant- I feel as though the phrase IQ has become so diluted by jackasses on social media who feel a need to brag about their IQ. Usually they got the results from some snake-oily trivia site. Because of this, that whenever I see a study that mentions IQ I immediately doubt it. What is a standard IQ test? What does it test for?

deleted 8y ago
[deleted]

ujal 8y ago

I will probably never understand IQ and its purpose for real life problems. It is either me who doesn't get it or all the people out there who lack introspection to understand what exactly it was that enabled them to grasp some new concept.

fejfieji 8y ago

This is logically impossible for the population as a whole, because IQ is defined as a relative metric. I.e. an IQ of 100 is (ideally) equal to whatever the current median intelligence is. It sounds like Norway's national service is just getting dumber by comparison.

marojejian 8y ago

The original article, btw: https://sci-hub.tw/http://www.pnas.org/content/early/2018/06/05/1718793115 https://sci-hub.tw/http://www.pnas.org/content/early/2018/06...

known 8y ago

The more testosterone a man has, the less likely he is to hang around to help bring up baby http://www.economist.com/news/science-and-technology/21679772-changes-mans-testosterone-level-show-kind-parent-he-will-be-pot-luck http://www.economist.com/news/science-and-technology/2167977...