A while ago I tried to estimate the IQ of chimpanzees and came up with a number so astronomically low that I dismissed the exercise as absurd. I began by noting that chimps have an average brain size of about 400 cc (cubic centimeters) while young adult white Americans have an average brain size of about 1395 cc. Within each sex, brain size correlates about 0.4 with IQ (0.44 corrected for reliability) and the within sex brain size standard deviation is 91 cc. What this means is that since diverging from chimps, brain size within each sex has increased by an astonishing 10.93 standard deviations.
Now part of this can be explained by the fact that white adult Americans are bigger than chimps, but even controlling for fat free body weight, their brains are still an astonishing 9.9 SD bigger than chimp brains.
Estimating chimp IQ from brain size alone
Now if we assume that the evolution of brain size was entirely caused by selection for greater intelligence, then the 0.44 correlation between IQ and brain size implies that chimps have an IQ that is 9.9 SD/0.44 = 22.5 SD below the white American mean. In other words, an IQ of -238.
Even if we assume that only half of the 9.9 SD increase in brain size was caused by selection for intelligence (perhaps the other half was for more advanced emotions and physical coordination), you still end up with a likely IQ of well below zero. And complex emotions only evolve to motivate intelligence to solve complex problems (what good is feeling fear if you’re too dumb to figure out how to escape danger?) so the evolution of one reflects the evolution of the other.
Estimating chimp IQ from both brain size and reaction time
But even an IQ of -238 might overestimate chimp intelligence, because chimps not only have much smaller brains than humans, but reaction times more than 0.61 SD slower than the white mean. Since brain size and reaction speed both correlate about 0.45 with IQ after correcting for range restriction and reliability, and research shows these variables correlate about 0.5 with one another, giving these variables standardized regression weights of 0.31 and 0.29 respectively, a multiple validity generalizations suggests chimps have IQs less than (-9.9 SD/0.31) – (0.61 SD/0.29) = -34.04 SD from the white mean. In other words, an IQ less than -411.
Is an IQ of -411 plausible?
At first I thought this was nuts. For scholar Richard Lynn had estimated chimps have the mental ability of a white three year old. Surely having the mind of three year old puts your IQ well into the positive double digits. For even the lowest deviation IQ in a billion whites is defined as IQ 10 (6 SD below the mean on a normalized curve) and far far more than one in a billion white adults has a mental age below three (those with profound retardation for example).
However in order for the IQ scale to be meaningful, it must be normed on only biologically normal people, and professional IQ tests exclude organic retardates and other impaired people from their samples, perhaps because those people have their own bell curves, and including them in the general population bell curve artificially inflates the left tail of the distribution. When IQ norms are limited to the biologically normal, adults with toddler mentality become impossibly rare.
Further, three-year-old humans are much much much smarter than adult chimps are. For starters, their brains are much closer in size to those of adult humans than they are to adult chimps’.
Secondly, unlike human three-year-olds, many chimps lack even the most basic self-awareness. Commenter Santoculto has called self-awareness the mother ship of human intelligence noting that humans are the only animal that can think about our own thoughts and strategies. This meta-cognition makes us light years more intelligent than chimps.
Thirdly, even one year old humans can ask questions, even just with one word (i.e. Mamma?). Not even the brightest chimps that have been trained to answer many questions with sign language have the cognitive ability to ask them. The ability to ask questions represents a quantum leap forward in intelligence, potentially equivalent to hundreds of IQ points.
It would explain a lot
The idea that chimps have an IQ as low as -411 may sound absurd, but it has some explanatory power. Commenter Swank has claimed that chimps have an IQ of 40 (a figure I used to believe) to insightfully argue that racial intelligence differences must be very small since IQ 40 is not that much lower than human IQ. If humans and chimps (separated for millions of years) only differ by a few dozen IQ points, then races separated by tens of thousands of years likely differ very little.
On the other hand, if the average British white has an genetic IQ 100, and the average chimps has an IQ less than -411, then that’s a gain of 511 IQ points in the 3.5 million years since apes left the trees, (more than 0.00015 points per year), predicting a 15 point gain in the 100,000 years since modern humans left Africa (the same as the famous 15 point black-white IQ gap in the U.S.).
Secondly, if humans really are hundreds of IQ points smarter than chimps, it would explain why we haven’t been invaded by space aliens. If humans are the much smarter than even our closest relatives, it implies human level intelligence is such an outlier, such a fluke, that nowhere else in the galaxy did that much brain power evolve.
Pumpkin Person 
Very interesting article, it make more sens than the ridiculously high figure of 40.
According to this method, given the fact that chimps are one of the smartest specie on Earth, the average IQ of the animal kingdom should be like -10000000000.
Btw, don’t you think if it exist life in the universe, it should also exist intelligent life if evolution is progressive ?
Btw, don’t you think if it exist life in the universe, it should also exist intelligent life if evolution is progressive ?
Yes, but human level intelligence is probably extremely rare, because even on this planet, no other animal comes even close to human IQ
I think if life existed for long enough human intelligence would evolve, but it would take such a long time because it’s such a high level.
You should do the same thing with dolphins because they have an EQ of 5 while humans have one of 7, but given the fact that dolphins are bigger than humans we should expect a similar intelligence.
And you should also make an article which show the expected EQ for each size of organism.
Well EQ is just the ratio of actual brain size to the statistically expected brain size for a given body size, so a high EQ just means you have a big brain for your body.
Yes, but independantly of intelligence smaller animals have a greater EQ, what I want is how you get the expected EQ for a given size ?
Yes, but independantly of intelligence smaller animals have a greater EQ, what I want is how you get the expected EQ for a given size ?
No they don’t, in fact that’s precisely what EQ was designed to prevent.
You see, originally biologists probably thought you could estimate an animal’s intelligence by its brain size/body size ratio, but because smaller animals have higher brain size/body size ratios than big animals, they came up with a more sophisticated method: EQ
EQ is ratio of brain size/expected brain size for a given body size
Yes, I understand it now, I thought EQ was only brain size body size ratio.
It should be possible to give a chimp an actual IQ test, right? They can do simple things like tell squares from circles, and sort things biggest to smallest.
Well scientist Richard Lynn estimated their IQ from their performance on Piaget type tasks. Since they seem to be at the level of a 3.5 year-old, he assigned them a mental age of 3.5 which equates to a ratio IQ of 3.5/adult mental age = 3/16= 0.22 = IQ = ratio IQ 22. However a ratio IQ of 22 equates to a deviation IQ of about 40, which strikes me as ludicrously high. Even 22 seems ludicrously high.
The problem is just because IQ tests are a good measure of IQ within humans, does not make them a good measure of IQ between species. To make an an analogy, arm span is an excellent measure of height among people with legs, but would overestimate the height of people with no legs. Chimps are the cognitive equivalent of no legs because they lack the most basic human brain power.
Good point, comparing the intelligence of humans and chimps is like comparing apples and oranges. Chimps are totally absent of some of the most basic human cognitive functions, like complex language comprehension and production. On the flip side, they’re clearly many magnitudes superior in some realms of cognition. See the following (I hope I haven’t posted this already, I’m sure you’ve seen this at some point before) :
wow those fucking chimps are really speed even when it come to tape on the screens its like they have lot more motor skills than human added to the memory
LOTJ, I’ve heard that chimp working memory research has been debunked because the chimps had tons of practice
Pumpkin, really ?
So chimps have lower working memory capacities than humans or they are still above at a lesser extent ?
So chimps have lower working memory capacities than humans or they are still above at a lesser extent ?
I read that they are lower when humans get just as much practice on that test, but I can’t find the source. The media ran with the sensational “chimps make monkeys out of college grads” headline, and buried the truth so deep I can’t find where I read it. Even the scientists are repeating it, it’s been said so much.
LOL I hate these sensational garbage .
It’s like you have to become a scientist yourself to find the truth about some subjects.
It is a very good reasoning that -411 seems much more plausable than Lynn’s 40.
However, seems that there’re also some discrepancies :
1. “…a gain of 511 IQ points in the 3.5 million years since apes left the trees, (more than 0.00015 points per year), predicting a 15 point gain in the 100,000 years since modern humans left Africa (the same as the famous 15 point black-white IQ gap in the U.S.).”
Yet in your previous entry you just argued that it’s plausible to gain 6 IQ points by just immigrating to America for Ashkenazi Israelis to reach teh level of Ashkenazi Americans.
Or you really want to argue that yes that 6-point IQ rise is possible, but they have to stay in America for another 40,000 years (=6/0.00015) ?
If it is remotely similar to the latter case, then the hypothesis that the Jewish IQ rise of 10-20 points in the last several hundred years alone because of being prosecuted becomes illogical in theory. On top of that, in an analogy: we have been actively prosecuting/hunting down many indigenous world populations, AND many animals too, such as chimps, wales, tigers, etc, in the last 200 years ar least, and we even have industrial-scaled slauterhouses of chichken and pigs nowadays too for Burger Kings, yet we don’t have evidences that any one of their IQ having a significant jump. Even though it could be an extreme analogy, IQ rise because of suffering from prosecution is a very dubious explaination bordering on impossibility.
2. “If humans are the much smarter than even our closest relatives, it implies human level intelligence is such an outlier, such a fluke, that nowhere else in the { galaxy } did that much brain power evolve.”
{ galaxy } ? That’s an obvious leap of logic, since 3.5-million-year is a such short a flash of time in terms of galaxy, and all the stars within them, development. It is entirely logicall that we humans don’t bother too much to send a spaceship to a remote tiny area to find out how some very very primitive lifeform behave, exactly like some extremely advanced lifeforms in space would find it meaninglessly insignifiant when looking at humans, which also could explain why they haven’t come over for a few drinks, yet.
Or they have already come here long ago, but not for a few drinks, but for some dulling scientific research of theirs. The fact that we “don’t konw” is due to the similar reason why some bacteria under the thick ice of the Sorth Pole “don’t know” that our scientists are actively researching these primitive things just inches away.
Perhaps because of the 10,000 year explosion known as human civilization, persecution caused huge rises in human intelligence (in certain population), Maybe this persecution doesn’t have the same impact on IQs below a certain threshold, like those of animals.
I don’t completely neglect the effect of it. The simple rationle is that the smartest, the most educated or the most skilled tend to survive the hardship/prosecution etc more than the the left half of the IQ bell curve does, which directly leads to the increase of avg IQ.
The “threshold” you mentioned is more to the point. More than that though, I believe IQ rise due to above cases would *soon* (generations?)be evened out by the way of Mean Reversion, in a sense that once the very prosecution/culture/market jobs etc pressures are relatively out, the avg IQ tend to goes back to the native race/sub-race average from the beginning. I think Ashkennazis, American or Israelis, will also be the case. It’s a bit like when one stops blowing a balloon, it’s more than a question of “threshold”.
That’s an obvious leap of logic, since 3.5-million-year is a such short a flash of time in terms of galaxy, and all the stars within them, development.
It is a short flash of time in the grand scheme of things, but extraordinary selection occurred during that 3.5 million years, because the cognitive gap between humans and all other animals is so great that we belong in an entirely different category. They have brains, we have minds. This implies the evolution of the mind was a fluke event, almost as much as a leap as the emergence of life itself.
Oh my god you are retard panda
correct(above):
[significant] IQ rise because of suffering from prosecution {within such a short span of time such as 100s of years } is a very dubious explaination bordering on impossibility {in eyes of mother nature}.
Actually, the explaination of the rise in Jewish IQ is not simple prosecution, there are more causes to this:
-Learning culture, study of the holy books–>to be good at these things it’s a very valuable trait in jewish culture.
-In Europe, all the markets jobs were let to the Jews while the gentiles were on the agriculture, war etc.. And to be wealthy was then a valuable trait.
I also wonder if the following experiment, or the similar, has ever be performed:
randomly choose some new-born chimps and put them into human society – nurseries, kindergardens, schools, homework, sports, tv, etc… i know there would be total chaos, but nonethelss give them entirely human environment as possible, then measure their avg IQ at different ages.
It must be interesting.
Pumpkin, what would be the SD of chimps if their average IQ is -411 ?
It must very low, like a -409 IQ chimp is a genius.
Thats a really stupid idea which can only came from a 90 IQ.
Pumpkin what do you think about koko the gorilla who supposedly have a 90 IQ ?
It seem impossible.
It’s meaningless. It’s like giving a reaction time test to a fly and since reaction time correlates with IQ in humans, concluding flies are smarter than humans because they have faster reaction times.
Or because arithmetic and chess are signs of intelligence in humans, concluding that computers are smarter than people because they can do those tasks better
Pumpkin I don’t ask you to do this, but is it possible to do this method to estimate the IQ of every animal species with a brain ?
Of course only for those with a mesurable reaction time.
There’s a floor below which it makes no sense, because differences in brain size between really primitive animals can’t reflect intelligence because they have none; instead it reflects only sensory processing
Pumpkin, you should estimate gorillas IQ with this method.
It could be interesting to compare them with chimps and with humans.
I don’t know if gorilla reaction time is known but i could estimate from brain size only…would probably underestimate their stupidity though since they are bad on both
Although some monkeys have faster reaction times than humans but this is negated by their super small brains
no, but pEEEpEEE does.
misdreavus is a chimp, but his IQ is at least 135+ on WAIS and also Binet
My IQ is 170 on the WAIS IV.
And the chimp here, is you with your 102 IQ.
UH OH here comes misdreavus with the 1-2 punch, beatin up on Pumpkin Person commenters between lunch, completing her graduate research assistantship, dropping knowledge on online neoreactionaries, twittering sassiness on twitter and organizing 20 person gang bangs at the bathhouse down the street.
LOL! It sounds like he has a full day.
Sockpuppets….
Who?
Humans diverged from chimps 7-8 million years ago, not 3.5 million years ago.
Intelligence has been under selection the entire time because even if you want to use the “the north african tropical forest retreated” line as the impetus for increased selection, the retreat started 10 million years ago.
Selection also doesn’t impact the mutation rate.
Increased height can explain much of the brain size increase. And you didn’t use brain size, you used cranial capacity.
You also contradict yourself on whether chimps have self-awareness. Here you say they don’t, but when convenient for you, you say they do: the same factors making chimps vis a vis humans a “special case” equally applied in other contexts where you tried to dismiss valid between human observations by applying the logic to chimps.
I said ancestral humans left the trees 3.5 million years ago. I realize we split from chimps much earlier.
Then there’s no reason to use chimp “brain size” if you’re talking about a change between “ancestral humans” (you actually wrote apes, which I have never heard referred to as ancestral humans) 3.5mya and now. The “511” point gain would have started much earlier — when humans and chimps diverged.
I assumed our ancestors had chimp brain size 3.5 million years ago, and were apes, as the term is commonly understood.
I know you did. This was an incorrect assumption. We had several other ancestors around this time with larger brains. The selection for increased brain size needs to take place from 7-8 million years, if you’re using chimp brain size.
I know you did. This was an incorrect assumption. We had several other ancestors around this time with larger brains
Like who?
The Austro genus generally had larger brains than chimps, although some were closer than others to chimps. Scientists don’t agree which species gave rise to genus homo.
But, the general assumption is faulty because the EQ only made significant jumps between austro and habilis and between erectus and sapiens. That’s about 600 cc of brain size since we diverged from chimps arguably due to intelligence increases.
Not only that, but the SD and brain size correlation of human cranial capacity shouldn’t be used. The correlation between brain size and intelligence between humans may not hold between species (and I’m not sure how’d you would test it, because you believe that IQ tests can’t validly measure the intelligence of other species on a human scale, which means there’s no way to know).
The Austro genus generally had larger brains than chimps
We’re not talking generally but specifically about the the brain size of our ancestors when they were last in the trees
The correlation between brain size and intelligence between humans may not hold between species (and I’m not sure how’d you would test it, because you believe that IQ tests can’t validly measure the intelligence of other species on a human scale, which means there’s no way to know).
I’m talking about within species level selection
Chimps aren’t a subgroup of humans….
Chimps aren’t a subgroup of humans…
That has nothing to do with what I just said.
The figures are for brain size between humans. You are applying them to expansions in brain size that took place within several other species.
True, but even in mice, the correlation between brain size and intelligence is similar to that in humans
So because the correlation between brain volume and IQ is similar in mice (where is this stat from? were mice given IQ tests?), the correlation between brain volume and IQ would be similar between all species homo and austro?
And also, according to you, chimps do possess self-awareness, culture, etc. and many “basic” features of human intelligence. So….are you now dropping that stance?
the correlation between brain volume and IQ would be similar between all species homo and austro?
The default assumption is that the relationship would average out to roughly the same. Of course the default assumption could be overturned with new data, but if we had data we wouldn’t need the default assumption,
And also, according to you, chimps do possess self-awareness, culture, etc. and many “basic” features of human intelligence.
According to me some chimps possess some self-awareness,but they lack meta-awareness, and they lack the ability to ask questions. This puts them quantum leaps behind human intellect.
The default assumption is that the relationship would average out to roughly the same.
The default assumption is that the relationship between different groups would average out to “roughly the same” as the correlation within groups? According to….?
According to me some chimps possess some self-awareness,but they lack meta-awareness
According to you right now. Above you said they lacked basic self-awareness and elsewhere you stated point-blank they had self-awareness. So yes, you are changing your earlier thoughts?
they lack the ability to ask questions
Are you using this as a proxy for curiosity? Or are you stating that their inability to use language to express curiosity is the ability?
The default assumption is that the relationship between different groups would average out to “roughly the same” as the correlation within groups? According to….?
You’re confusing correlation with relationship & you’re confusing within group selection with between group selection.
According to you right now. Above you said they lacked basic self-awareness
I said many of them lack basic self-awareness.
Are you using this as a proxy for curiosity? Or are you stating that their inability to use language to express curiosity is the ability?
Curiosity is the desire to know more. What chimps lack is the ability to question.
Anyway feel free to point out how selection that occurred within several different species is within (human) group selection.
Anyway feel free to point out how selection that occurred within several different species is within (human) group selection.
Because selection within a species is what causes it to evolve into a new species & selection within that species causes it to evolve into the next species.
Pumpkin how the incredible working memory of the chimp was debunked ?
Have you any evidences ?
See my last comment
The correlation within humans of brain size and IQ is not .40. It is close to .25. http://ssrn.com/abstract=2512128
This value is without correction for height/body size, which biases things. What we are really interested in is the correlation between brain variables and cognitive ability _controlling for_ height/body size.
I disagree with that meta-analysis. Jensen said 0.4, Rushton said 0.4, and there’s a scientist named Wickett who claimed that when you correct for range restriction the correlation is closer to 0.5
Further there have been massive studies involving thousands and thousands of kids that found even simple head circumference correlates 0.23 with IQ. Given that HC correlates only 0.6 with brain size, we’d expect the IQ brain size correlation to be close to 0.4
The meta-analysis you cite over-reported zero correlations in my humble opinion.
Jensen and Rushton’s opinions were based on earlier, worse reviews (i.e. boosted by publication bias). Just read the paper, not all these ad hoc plausibility arguments.
I looked at the paper back when it first came out, and from what I understood, they over-corrected for publication bias and failed to correct for range restriction.
You’re correct that Rushton & Jensen failed to correct for publication bias, but they also failed to correct for range restriction, so their errors at least cancelled each other out,. allowing them to make a more accurate estimate in my humble opinion.
In fact they did not correct for publication bias at all. Instead their method was to seek out unpublished papers. So I don’t understand your claim. There two ways to deal with publication bias: 1) use a correction method (e.g. PET-PEESE, p-uniform, trim and fill) or 2) gather a representative collection of studies. They did the latter.
Jensen relied on previous reviews so his word is nothing special here. Rushton (with Ankney) did his own two reviews. Rushton’s reviews suffer from publication bias because they did not correct for it or seek out unpublished studies. The new review is superior: far larger and more representative.
As for range restriction, you are welcome to go thru the papers and note which are university students and which are not.
In the end, whole brain size itself is not so interesting anyway. http://emilkirkegaard.dk/en/?p=5034 http://www.sciencedirect.com/science/article/pii/S0160289615000616
In fact they did not correct for publication bias at all.
They corrected for it in the sense that they tried to eliminate it by including unpublished data. So if someone reported an insignificant correlation, but failed to specify the exact number, they contacted the person to get that number, which was probably quite low, since it was insignificant. This dragged down the correlation between IQ and brain size
The problem is they didn’t do the reverse. If someone reported a significant correlation but didn’t specify what it is, did they contact those researchers to get the exact number? From what I could tell, no. So you have them bending over backwards to hunt down correlations that are likely low, but failing to hunt down correlations that are likely high.Now maybe there were no likely high correlations that required hunting down because they were already given in the studies, but the paper didn’t clarify so who knows.
As for range restriction, you are welcome to go thru the papers and note which are university students and which are not.
It’s not just university students, it’s any sample with less variance than the general U.S (white). population.I suspect that if I ever find time to correct all the studies for range restriction, the correlation would rise by at least 0.1, bringing it close to Rushton’s 0.4
In the end, whole brain size itself is not so interesting anyway.
I think it’s absolutely fascinating. Overall brain size is analogous to overall intelligence, while size of specific brain regions is analogous to specific cognitive abilities.
you should make this estimation for all the apes and prehuman species
should make this for dolphin and crows too ?
how do you explain the intelligence of ants ? even if they may have a collective intelligence, but this intelligence ust have an origin ? does this make them more evolved than some dumb mammals like for exemple..rabbits ?
Can you make some funny articles in which you estimate the average IQ of humanity whithout some ethnics groups ? l(ike for exemple what would be the IQ of humanity without the african)
Do you believe in the verbal/spatial dichotomy of intelligence like some commenters of this blog ?
Or do you think that you can be good at math woithout particular spatial talent ?
because you can be good at arithmetic problem without being good at spatial ?
do you believe that spatial abilities are general ones ? because spatial abilities are useful only in the space and you can be in an olfactive environment for exemple.
It may just be a parallel effect of augmentation of g in cold environment, (and that could explain why jews have high g without be good at spatial.)