Why does IQ cluster around 100 points?

[barbos]

Yeah, using head makes you hungry fast.
I remember test seasons in university. I had to eat 4 times a day and it cost a lot of money.

 

[Speakpigeon]

The point being that we may accept that intelligence is theoretically limited; But there's no reason at all to imagine that we are even 1% of the way to that limit.

I couldn't point you to anything that proves this empirically, but to me the shape of the curve as well as the raw physics of genetics suggests that there is a very real, hard limit.

- IQ measures problem solving ability, and at some point the real, material problems of the world don't require more fire-power, and instead one could argue that many jobs have as much of a social component as they do a problem solving one. Consider a person with an average IQ, and a normal temperament, vs another with an IQ of 160 who is completely socially maladjusted (I saw a couple of these people in college). In terms of life outcomes the person with an average IQ will have more career and reproductive success, because they can talk to people and build a network.

There may be a real bias in this observation. Many high-IQ people may well decide not to wear their intelligence on their sleeve, for whatever reasons, including emotional. If you like the warmth of the huddled masses, you make sure you fit, and if you're intelligent, it's easier to solve the problem of how to fit.

I seems to me your conception of intelligence isn't in fact problem-solving ability, but a particular, narrower kind of problem-solving ability, like, say, mathematics, quantum physics, etc.

- Genetically, problem solving skill and the resulting bell curve should be a product of genotypic variation, but the average real, problem solving skill (aka 100 points) isn't actually very high, and as we get closer to genius levels the curve tapers off dramatically. There isn't even a slow decline, 70 out of every 100 people have essentially the same ok problem solving skill, and then there is everyone else. That the average landed in this range can't be arbitrary, there has to be a reason why more people landed at that level as opposed to others.

As I see it, the main reason, probably the only reason, there's a fat middle in the IQ range, is that the more intelligent people still haven't figured out how to get rid of this rather embarrassing fat middle. Less intelligent people essentially do the menial chores high-IQ people don't want. So, lower IQ people are essentially like the servants and peasants the king and the noblemen couldn't do without.

Just wait.

As soon as AIs machines can do it better, more efficiently, using less energy, causing less pollution, do the job without asking for a share of the political power etc., we'll see the fat middle going extinct, one way or another.

if life provided challenges that meant only people with a 140 IQ could survive, then the curve would shift dramatically to the right. But maybe it's that the challenges that are inherent to being a person in the world mostly require a brain with an IQ hovering around 100, along with other well adjusted components.

The high-IQ group could survive without the rest. It's just that it's way more convenient for now at least, or even that they just prefer to keep the 100-IQ people around. Maybe they like us, somehow. We ourselves like to keep dogs and cats and cattle around. Same thing, I would assume. And you definitely need at least some people to play American football, I think.

At least, if they are really more intelligent, as suggested by the relative scores, and if they really wanted to get rid of the rest, that would already be done and a long time ago. So, either they're not smart enough to find out how to do it, or they really like us.

Gosh, that has to be good news!
EB

 

[rousseau]

I seems to me your conception of intelligence isn't in fact problem-solving ability, but a particular, narrower kind of problem-solving ability, like, say, mathematics, quantum physics, etc.

As I understand it IQ measures a person's ability to solve unique problems.

You're a hunter-gatherer and you fall through a sheet of ice, or get stuck on the other side of a stream. A part of your brain (intelligence) allows you to solve the problem and survive. This is why to do things like software development or engineering typically requires high IQ: because the problems are relatively complex compared to those presented in day to day life.

But consider that surviving in a group of people doesn't require pure problem solving ability, but also other skills like EQ. This means that the right mix of brain components doesn't just produce a highly logical person, but also one with other important skills. And consider that potentially a high IQ comes at the expense of these other brain components. So someone with high IQ may be able to exploit a niche requiring intense creativity, but not another one requiring sociality (sales, teaching, social work, nursing etc).

And so it may just be that at some point more problem solving ability offers diminishing returns, and other skills and personality traits offer more value. So a 'smart' or 'fecund' person isn't just someone with a high IQ but rather the right mix of IQ and other things.

 

[Speakpigeon]

Brains are costly to run.

Definitely.

The more intelligence the more it costs to run the brain.

Well, I'm not sure of that. You may be confusing being intelligent and thinking hard. But, that's definitely not the same thing.

Being intelligent may just be having a more energy-efficient brain such that thinking to solve a problem doesn't require as much energy.

And if that is true, that would have made a powerful selective advantage, one that could explain the rise of Homo Sapiens perhaps.

Nowadays, I think the kind of communism we have in modern societies would blunt if need be all possibilities of natural selection and evolution.

There's a point at which you don't get enough benefit from the extra intelligence to pay the cost of running the additional brain.

Yes, it might be.

Show

At least that's why I evolved to limit myself.

EB

 

[Loren Pechtel]

You're a hunter-gatherer and you fall through a sheet of ice, or get stuck on the other side of a stream. A part of your brain (intelligence) allows you to solve the problem and survive. This is why to do things like software development or engineering typically requires high IQ: because the problems are relatively complex compared to those presented in day to day life.

I really like this description of intelligence!

But consider that surviving in a group of people doesn't require pure problem solving ability, but also other skills like EQ. This means that the right mix of brain components doesn't just produce a highly logical person, but also one with other important skills. And consider that potentially a high IQ comes at the expense of these other brain components. So someone with high IQ may be able to exploit a niche requiring intense creativity, but not another one requiring sociality (sales, teaching, social work, nursing etc).

And note how those high in the intelligence realm are often a bit lacking in the social realm.

 

[Loren Pechtel]

Definitely.



Well, I'm not sure of that. You may be confusing being intelligent and thinking hard. But, that's definitely not the same thing.

The brain has a base energy use that you pay whether you are using the intelligence or not. It's like a high horsepower car gets lower mileage than the same car with a lesser engine even if it's driven the same.

 

[rousseau]

Definitely.



Well, I'm not sure of that. You may be confusing being intelligent and thinking hard. But, that's definitely not the same thing.

The brain has a base energy use that you pay whether you are using the intelligence or not. It's like a high horsepower car gets lower mileage than the same car with a lesser engine even if it's driven the same.

At some point the size of the brain also becomes a risk during pregnancy, too, which is why infancy is a thing.

 

[bilby]

Definitely.



Well, I'm not sure of that. You may be confusing being intelligent and thinking hard. But, that's definitely not the same thing.

The brain has a base energy use that you pay whether you are using the intelligence or not. It's like a high horsepower car gets lower mileage than the same car with a lesser engine even if it's driven the same.

At some point the size of the brain also becomes a risk during pregnancy, too, which is why infancy is a thing.

The heuristic 'X is the reason why Y' is a dangerous intellectual shortcut; Reality is typically FAR more complex than that.

When it comes to evolved biological traits, this mode of thought is wrong more often than it is right. The sheer number of degrees of freedom in biological evolution is vast, and effects rarely have fewer than dozens of causes; often have thousands of causes; and as far as I am aware never have a single definitive cause.

Science uses a hierarchy of levels of abstraction, so mathematics is provable and can produce definitive statements of fact; physics is an abstraction of mathematics; chemistry is an abstraction of physics; biology is an abstraction of chemistry; and evolutionary theory and psychology (of which discussion of 'intelligence' is a part) are abstractions of biology.

At each level, different tools are required, and the rules are statistical summaries of the underlying rules at the previous level. It's theoretically possible to model (almost) everything using quantum physics, but trying to do chemistry by calculating the quantum states of all of the subatomic particles would be practically impossible for all but the simplest interactions.

The claims you are making about intelligence appear to be founded in the simplifying assumption that the huge degree of complexity at the evolutionary level can be safely disregarded in favour of an heuristic that allows us to make simple logical connections between effects and their supposed causes. But we know that this is far less likely to be true at the biological level, and that while it's necessary to speak at the next level of abstraction beyond biology in order to say anything at all about the subject, its also impossible with the current state of human knowledge to do so with great confidence.





TL;DR - It's all a LOT more complicated than that.

 

[Speakpigeon]

You're a hunter-gatherer and you fall through a sheet of ice, or get stuck on the other side of a stream. A part of your brain (intelligence) allows you to solve the problem and survive. This is why to do things like software development or engineering typically requires high IQ: because the problems are relatively complex compared to those presented in day to day life.

I really like this description of intelligence!

But consider that surviving in a group of people doesn't require pure problem solving ability, but also other skills like EQ. This means that the right mix of brain components doesn't just produce a highly logical person, but also one with other important skills. And consider that potentially a high IQ comes at the expense of these other brain components. So someone with high IQ may be able to exploit a niche requiring intense creativity, but not another one requiring sociality (sales, teaching, social work, nursing etc).

And note how those high in the intelligence realm are often a bit lacking in the social realm.

Which just go on to show that people are equivocating when they equate without qualifications an IQ with an ability to solve problems. It seems fair enough to admit IQs measure an ability to solve some problems, at least those which are part of the test itself, and from there presumably a class of real-life problems although this is already a rather fuzzy proposition. In any case, IQs don't measure the capability to solve problems. At best, it's a measure to solve a class of problems, class which may well be a small fractions of the range of problems people typically encounter in their lives.

As far as I am concerned, intelligence is whatever people mean to refer to when they use the word "intelligence".

Here is a small sample of the typical definitions found in dictionaries.

1. The ability to acquire, understand, and use knowledge: a person of extraordinary intelligence.
1. (Psychology) the capacity for understanding; ability to perceive and comprehend meaning
2. good mental capacity: a person of intelligence.
1. capacity for learning, reasoning, and understanding; aptitude in grasping truths, relationships, facts, meanings, etc.
2. mental alertness or quickness of understanding.
3. manifestation of a high mental capacity.
4. the faculty or act of understanding.

As I see it, any claim to measure intelligence should be consistent with these definitions. According to these definitions, the notion of a problem-solving capability isn't intelligence, unless, perhaps, if it could be properly argued, and as I have just argued, IQs are not a measure of problem-solving capabilities. This should be the implication of what you all seem to accept here, that intelligent people may be very bad at solving a particular class of problems, e.g. problems relative to social relations. So, IQs are just not measuring intelligence. IQED
EB

 

[Speakpigeon]

Well, I'm not sure of that. You may be confusing being intelligent and thinking hard. But, that's definitely not the same thing.

The brain has a base energy use that you pay whether you are using the intelligence or not. It's like a high horsepower car gets lower mileage than the same car with a lesser engine even if it's driven the same.

This still doesn't logically imply your initial claim I was responding to that "the more intelligence the more it costs to run the brain".

Given the range of brains that exist in humans, and for all we know, it may well be the case that the more intelligence the less it costs to run the brain.

At least, this seems to make very good sense as it would go some way in explaining the biological basis for intelligence in humans.
EB

 

[Speakpigeon]

At some point the size of the brain also becomes a risk during pregnancy, too, which is why infancy is a thing.

The heuristic 'X is the reason why Y' is a dangerous intellectual shortcut; Reality is typically FAR more complex than that.

When it comes to evolved biological traits, this mode of thought is wrong more often than it is right. The sheer number of degrees of freedom in biological evolution is vast, and effects rarely have fewer than dozens of causes; often have thousands of causes; and as far as I am aware never have a single definitive cause.

Science uses a hierarchy of levels of abstraction, so mathematics is provable and can produce definitive statements of fact; physics is an abstraction of mathematics; chemistry is an abstraction of physics; biology is an abstraction of chemistry; and evolutionary theory and psychology (of which discussion of 'intelligence' is a part) are abstractions of biology.

At each level, different tools are required, and the rules are statistical summaries of the underlying rules at the previous level. It's theoretically possible to model (almost) everything using quantum physics, but trying to do chemistry by calculating the quantum states of all of the subatomic particles would be practically impossible for all but the simplest interactions.

The claims you are making about intelligence appear to be founded in the simplifying assumption that the huge degree of complexity at the evolutionary level can be safely disregarded in favour of an heuristic that allows us to make simple logical connections between effects and their supposed causes. But we know that this is far less likely to be true at the biological level, and that while it's necessary to speak at the next level of abstraction beyond biology in order to say anything at all about the subject, its also impossible with the current state of human knowledge to do so with great confidence.

TL;DR - It's all a LOT more complicated than that.

Yes, I agree it must be a very complex thing.

Still, I think you are being a bit harsh with rousseau here. He didn't do what you seem clearly to suggest he did. He was talking of "a reason why", you are talking of causes. So, there's already a semantic gulf. Further, unlike causes, reasons are definitely things we know of and understand, and as such they are what humans can trade between themselves to come to a consensus as to what, then, might be causes. Sciences doesn't work differently, in that it's just the most effective process we know of to arrive at what we can agree are not only very good reasons, but our very best reasons, and reasons to arrive at a consensus as to causes.

I agree with rousseau that the size of the brain is definitely a risk during parturition and as such a limiting constraint to the size of the brain in humans, and, plausibly, a limiting constraint on human intelligence. I would assume that's a reasoning accepted by the specialists.

And we're not even doing any kind of science here, so our reasons can only be a bit fuzzy.

And actual causes must be at quantum level, so we're very, very unlikely ever to tease them out. All we have are reasons to believe in causes.
EB

 

[untermensche]

The intelligence in humans that made them most fit to survive is group intelligence. The intelligence of a group working towards a goal, like the goal of killing some large predator or large powerful prey, or the goal of building shelter.

That's a very good point.

Individual intelligence is pretty meaningless and only has a chance to really express itself once civilization exists.

Still, I'm not sure there's anything other than specialised intelligence. Some people are good a Lego, others are good at relationships, etc. So, "group intelligence" wouldn't be enough of itself. You would need to have that plus the individual intelligence of at least some of the individuals in the group. A leader using the specialised skills of the others.

Still, this aspect seems a derail to me.
EB

A derail?

The fact is there is no cluster of anything.

There are unrelated individuals pigeon-holed by a 2 dimensional graphing of a specific test.

While human variability exists in multiple dimensions.

All humans are unique.

All the test looks at is the answer, not how the mind get's the answer which is the intelligence. So the test is actually blind to individual intelligence and differences in intelligence, differences in how minds reach an answer.

There are no clusters anywhere except fragmented cultural clusters.

The most important intelligence for humans and the intelligence that takes you the furthest is social intelligence.

And no IQ test looks at that.

 

[Jokodo]

The point being that we may accept that intelligence is theoretically limited; But there's no reason at all to imagine that we are even 1% of the way to that limit.

I couldn't point you to anything that proves this empirically, but to me the shape of the curve as well as the raw physics of genetics suggests that there is a very real, hard limit.

The shape of the curve suggests no such thing. If we had a way to measure intelligence on some "objective" and more importantly absolute scale in units derived from metres, seconds and kilograms (which we don't), and if, on that scale, the distribution would be a uniform one with all values in a range from 0 to 5000 objective intelligence units (OIU) equally frequent, the curve as regards IQ would still be a bell-shaped normal distribution: As per the definition of the IQ scale, 2500 OIUs would be mapped to an IQ of 100, 1056 OIUs to an IQ of 85, and 3944 OIUs to an IQ of 115 (that's the mean +/- one standard deviation in a uniform distribution over a range of 0-5000).

That's how the IQ scale is calibrated. If Jack and John have an IQ of 140 and 70 respectively, this does not in any meaningful sense mean that Jack is twice as intelligent as John. It only means that Jack is two and a half standard deviations above the mean, while John is two below. Depending on the the underlying distribution, and pretending that we had an absolute scale to measure intelligence against (which, again, we don't), this could be true if they have almost the exact same intelligence very close to some hard limit (if everyone has essentially the same intelligence, very small deviations can put you several standard deviations away from the mean), or it could mean Jack's intelligence is several 1000 times that of John if the values are all over the place.

Nothing, literally nothing, about the actual distribution of intelligence is implied by the distribution of IQs.

 

[Speakpigeon]

The most important intelligence for humans and the intelligence that takes you the furthest is social intelligence.

And no IQ test looks at that.

Sure, this last bit, good point again, but why should we conceive of "social intelligence" as "the most important intelligence"? Important with regard to what? Having a good social life?

Humans only add up to about one ten-thousandth of the life on Earth, measured by the dry weight of the carbon that makes up the structure of all living things, also known as biomass. The planet’s real heavyweights are plants. They outweigh people by about 7,500 to 1, and make up more than 80 percent of the world’s biomass, a study in Monday’s Proceedings of the National Academy of Sciences said.

And what is social intelligence to begin with?

Social intelligence is the capacity to know oneself and to know others. Social scientist Ross Honeywill believes social intelligence is an aggregated measure of self- and social-awareness, evolved social beliefs and attitudes, and a capacity and appetite to manage complex social change. Psychologist, Nicholas Humphrey believes that it is social intelligence, rather than quantitative intelligence, that defines who we are as humans.
https://en.wikipedia.org/wiki/Social_intelligence

EB

 

[untermensche]

Sure, this last bit, good point again, but why should we conceive of "social intelligence" as "the most important intelligence"? Important with regard to what? Having a good social life?

A social life is essential for mental health.

But I'm talking about a person's working life.

The intelligence that is most important once the nonsense of taking worthless tests ends is social intelligence.

That is how you get ahead.

Leadership skills. That is also how you get ahead.

No IQ test looks at that.

No IQ test looks at anything all that important. All that can be looked at are answers. Which were known ahead of time by the test makers. The intelligence that got the answer is not seen on any test.

 

[rousseau]

The point being that we may accept that intelligence is theoretically limited; But there's no reason at all to imagine that we are even 1% of the way to that limit.

I couldn't point you to anything that proves this empirically, but to me the shape of the curve as well as the raw physics of genetics suggests that there is a very real, hard limit.

The shape of the curve suggests no such thing. If we had a way to measure intelligence on some "objective" and more importantly absolute scale in units derived from metres, seconds and kilograms (which we don't), and if, on that scale, the distribution would be a uniform one with all values in a range from 0 to 5000 objective intelligence units (OIU) equally frequent, the curve as regards IQ would still be a bell-shaped normal distribution: As per the definition of the IQ scale, 2500 OIUs would be mapped to an IQ of 100, 1056 OIUs to an IQ of 85, and 3944 OIUs to an IQ of 115 (that's the mean +/- one standard deviation in a uniform distribution over a range of 0-5000).

That's how the IQ scale is calibrated. If Jack and John have an IQ of 140 and 70 respectively, this does not in any meaningful sense mean that Jack is twice as intelligent as John. It only means that Jack is two and a half standard deviations above the mean, while John is two below. Depending on the the underlying distribution, and pretending that we had an absolute scale to measure intelligence against (which, again, we don't), this could be true if they have almost the exact same intelligence very close to some hard limit (if everyone has essentially the same intelligence, very small deviations can put you several standard deviations away from the mean), or it could mean Jack's intelligence is several 1000 times that of John if the values are all over the place.

Nothing, literally nothing, about the actual distribution of intelligence is implied by the distribution of IQs.

I'm not sure what you're trying to say here in reference to my post.

If we create a test that measures pure problem solving skill, and the results are a bit fuzzy, but generally stable at any given point in time in a population, controlling for other factors, then that means a few things:

1) We do have a reasonable idea of how intelligence, as defined as problem solving skill which is what IQ is, is distributed across a population. As far as I understand it this isn't very controversial science in terms of it's validity, despite the people who object. If you can point me to something that proves otherwise I'll turn on a dime.

2) The shape of the distribution defines how that population scores on problem solving skill. So while an IQ of 140 doesn't say anything in of itself, the characteristics of those who are in the range do, and we can also measure the rarity of those with that IQ in reference to the rest of the bell curve. We can also see how the bell curve is distributed: by your very math an IQ of 1000 is a mathematical impossibility, which suggests some form of phenotypic variation (and upper limit) that clusters in what we've defined as an IQ of 100. This is where biological limits come into play - if the component and/or components of the brain responsible for problem solving skill are the result of a continuum of genes, then we should get a normal distribution [granted this is a bit fuzzy]. And if at some point more problem solving power becomes maladaptive we shouldn't see the brain turn into a pure problem solving machine.

3) Because IQ does say something about our problem solving skill, it's measurement is generally predictive of, for example, the IQ of people in different professions, how many babies people have, wealth, educational attainment, and a whole host of other things. With that in mind I don't know how you can claim that IQ doesn't measure anything, unless I'm not understanding what you're trying to say.

 

[rousseau]

At some point the size of the brain also becomes a risk during pregnancy, too, which is why infancy is a thing.

The heuristic 'X is the reason why Y' is a dangerous intellectual shortcut; Reality is typically FAR more complex than that.

When it comes to evolved biological traits, this mode of thought is wrong more often than it is right. The sheer number of degrees of freedom in biological evolution is vast, and effects rarely have fewer than dozens of causes; often have thousands of causes; and as far as I am aware never have a single definitive cause.

Science uses a hierarchy of levels of abstraction, so mathematics is provable and can produce definitive statements of fact; physics is an abstraction of mathematics; chemistry is an abstraction of physics; biology is an abstraction of chemistry; and evolutionary theory and psychology (of which discussion of 'intelligence' is a part) are abstractions of biology.

At each level, different tools are required, and the rules are statistical summaries of the underlying rules at the previous level. It's theoretically possible to model (almost) everything using quantum physics, but trying to do chemistry by calculating the quantum states of all of the subatomic particles would be practically impossible for all but the simplest interactions.

The claims you are making about intelligence appear to be founded in the simplifying assumption that the huge degree of complexity at the evolutionary level can be safely disregarded in favour of an heuristic that allows us to make simple logical connections between effects and their supposed causes. But we know that this is far less likely to be true at the biological level, and that while it's necessary to speak at the next level of abstraction beyond biology in order to say anything at all about the subject, its also impossible with the current state of human knowledge to do so with great confidence.

TL;DR - It's all a LOT more complicated than that.

Yes, I agree it must be a very complex thing.

Still, I think you are being a bit harsh with rousseau here. He didn't do what you seem clearly to suggest he did. He was talking of "a reason why", you are talking of causes. So, there's already a semantic gulf. Further, unlike causes, reasons are definitely things we know of and understand, and as such they are what humans can trade between themselves to come to a consensus as to what, then, might be causes. Sciences doesn't work differently, in that it's just the most effective process we know of to arrive at what we can agree are not only very good reasons, but our very best reasons, and reasons to arrive at a consensus as to causes.

I agree with rousseau that the size of the brain is definitely a risk during parturition and as such a limiting constraint to the size of the brain in humans, and, plausibly, a limiting constraint on human intelligence. I would assume that's a reasoning accepted by the specialists.

And we're not even doing any kind of science here, so our reasons can only be a bit fuzzy.

And actual causes must be at quantum level, so we're very, very unlikely ever to tease them out. All we have are reasons to believe in causes.
EB

Na he's right, I didn't really think that post through. It is true that head-size is a risk during pregnancy, but I don't know how plausible it is that this is a limiting factor to intelligence. If anything it's probably just a limiting factor to the length of child-hood, and the need for infancy.

 

[Speakpigeon]

Sure, this last bit, good point again, but why should we conceive of "social intelligence" as "the most important intelligence"? Important with regard to what? Having a good social life?

A social life is essential for mental health.

But I'm talking about a person's working life.

The intelligence that is most important once the nonsense of taking worthless tests ends is social intelligence.

That is how you get ahead.

Leadership skills. That is also how you get ahead.

So, social intelligence is essential for mental health... OK.

Isn't some intelligence beyond social intelligence required to be in good mental health, anyway? If you don't understand what's going on around you, it has to be a problem and eventually a risk for your mental health.

Still, human beings are social animals so, obviously, social intelligence is important.

But, I still have no reason to accept that social intelligence is the most important form of intelligence. Nothing you've said here seems conclusive to me.

No IQ test looks at that.

No IQ test looks at anything all that important. All that can be looked at are answers. Which were known ahead of time by the test makers. The intelligence that got the answer is not seen on any test.

Irrelevant to my post.
EB

 

[untermensche]

So, social intelligence is essential for mental health... OK.

Where did I say that?

Please be specific.

That shows either an inability to read or some twisting that takes place after reading.

Show me specifically where I said that.

 

[Jokodo]

The shape of the curve suggests no such thing. If we had a way to measure intelligence on some "objective" and more importantly absolute scale in units derived from metres, seconds and kilograms (which we don't), and if, on that scale, the distribution would be a uniform one with all values in a range from 0 to 5000 objective intelligence units (OIU) equally frequent, the curve as regards IQ would still be a bell-shaped normal distribution: As per the definition of the IQ scale, 2500 OIUs would be mapped to an IQ of 100, 1056 OIUs to an IQ of 85, and 3944 OIUs to an IQ of 115 (that's the mean +/- one standard deviation in a uniform distribution over a range of 0-5000).

That's how the IQ scale is calibrated. If Jack and John have an IQ of 140 and 70 respectively, this does not in any meaningful sense mean that Jack is twice as intelligent as John. It only means that Jack is two and a half standard deviations above the mean, while John is two below. Depending on the the underlying distribution, and pretending that we had an absolute scale to measure intelligence against (which, again, we don't), this could be true if they have almost the exact same intelligence very close to some hard limit (if everyone has essentially the same intelligence, very small deviations can put you several standard deviations away from the mean), or it could mean Jack's intelligence is several 1000 times that of John if the values are all over the place.

Nothing, literally nothing, about the actual distribution of intelligence is implied by the distribution of IQs.

I'm not sure what you're trying to say here in reference to my post.

If we create a test that measures pure problem solving skill, and the results are a bit fuzzy, but generally stable at any given point in time in a population, controlling for other factors, then that means a few things:

1) We do have a reasonable idea of how intelligence, as defined as problem solving skill which is what IQ is, is distributed across a population.

IQ is not problem solving skills. IQ is one particular scale to express problem solving skills, one that happens to be calibrated on the distribution in the population. The fact that the median is is (close to) 100 and the standard deviation (close to) 15 literally only tells us that the people who shipped the latest series of tests did their job right. IQ is like temperature in that IQ 101 is above IQ 100, and IQ 110 is above either, but it is very much unlike temperature in that only for temperature, a kg of water at 101 K contains 1.01 times the caloric energy of a kg of water at 100 K, and one at 110 K 1.1 times the caloric energy. Nothing of the like can be deduced. IQ is not an absolute scale.

Imagine we lacked a way to relate temperatures to heat energy contents, and could only tell which object is hotter out of two. Imagine that we defined human body temperature as "normal", the temperature of the background radiation as "pretty cold", and the surface temperature of an average star as "pretty hot". And because numbers are cheaper to store and easier to make calculations with, and because not everyone speaks English, we'd frequently refer to these as "Temperature Quotient (TQ) 85" for "pretty cold", TQ 100 for "normal", and TQ 115 for "pretty hot", with values below 50 only occurring in lab conditions, and values above 150 only in supernovae.

The IQ as defined by the psychometric community is very much analogous to that TQ, and not at all to Kelvins. The fact that most people have an IQ between 85 and 115 is about as remarkable as the fact that most of the universe has temperatures from TQ 85 to TQ 115. Trying to deduce from this some truths about the world is mistaking the map for the landscape.