[NOTE FROM PUMPKIN PERSON: PLEASE PLACE ALL OFF-TOPIC COMMENTS HERE. THEY WILL NOT BE POSTED IN THIS THREAD]
Before investigating the IQ of chimps, it’s interesting to ask what the expected IQ chimps should have given their brain size.
Chimp brain size predicts an IQ of 20
The average chimp has a cranial capacity of about 400 cubic centimeters. The average cranial capacity of white adults in modern Western countries is not known because most of the cited figures come from people who lived before WWII and we know brain size like height has increased since then. Perhaps the best estimate for modern white cranial capacity is 1474 cubic centimeters, since this is the cranial capacity of Eurasians before the malnutrition and disease of agriculture shrunk our brains and bodies, and with modern nutrition, we’ve hopefully recovered this lost brain size in the generations since WWII!
Given that the within sex standard deviation for cranial capacity among whites is about 91 cc, this implies the chimps are 11.8 standard deviations smaller in brain size than modern whites. Given about a 0.45 within sex correlation between brain size and IQ in Western samples, this predicts their IQs would be 11.8 SD(0.45) = 5.31 SD below the white mean. Given that the (white) American mean and SD for IQ are defined as 100 and 15 respectively, this equates to an IQ of 100 – 5.31(15) = 20 (white norms)
How do chimps score on “IQ tests”?
In 2007 there was a fascinating study that compared human 2.5 year-olds to chimps and other apes on a battery of intelligence tests. With the exception of social intelligence, where the human toddlers were way ahead, the apes and toddlers had the same intelligence.
In other words, chimps have the same intelligence as a 2.5 year old (white) human.
What adult IQ does a mental age of 2.5 equate to? The question is a lot trickier than it seems. One could define adult mental age as 16+ and then use the age ratio method to conclude that since 2.5 is 16% of 16, a mental age of 2.5 equates to an adult IQ of 16. The problem with this method is it assumes intelligence develops as a function of age in a linear way, which is an oversimplification.
What is needed is an actual intelligence test that’s been given to both adults and to toddlers and one where scores increase on an interval scale.
One such test is digit span. Since the earliest days of intelligence testing (digit span has virtually no Flynn effect) it’s been known that by the age of three, a white child can repeat two digits, which probably means a 2.5 year old can repeat one digit.
By contrast U.S. adults average a forward digit span of 6.645 with a standard deviation of 1.35 and since races in the U.S. differ very little on forward digit span, this should be taken as the white adult distribution. This means that an adult who performs like a 2.5 year-old (digit span of 1) is 4.18 standard deviations below the white adult average.
If we assume that most cognitive abilities are like digit span, then chimps (who score like 2.5 years olds on most tested cognitive functions) perhaps average 4.18 standard deviations below white adults on the average test.
Does this mean their IQs average 4.18 SD below the average white adult? No, because if you score 4.18 SD below white adults on the average test, your composite score on a battery of tests is actually much lower. Why? Because it’s much more rare to average an extremely low score across a battery of tests than it is to score that low on any one test. Indeed based on the intercorrelation of WAIS-IV subtests, someone who is 4.18 SD below average on the average subtest, would be 5.73 standard deviations (86 IQ points) below average on the composite score, thus my best guess for the average IQ of chimps is 14 (white norms).
This is remarkably close to the predicted IQ of 20 based on chimp brain size. The fact that the IQ of a species separated from us by over 6 million years of evolution, can have their IQs so closely predicted by the same regression line predicting Western human IQ from Western human brain size, suggests that it’s possible to create culture reduced IQ tests that transcend not only culture, time and space, but species too.
IQ is measuring something very real and biological.
Pumpkin Person 
Is this higher or lower than Southern Europeans Pumpkin?
Funny guy.
“If we assume that most cognitive abilities are like digit span”
Baseless assumption.
“IQ is measuring something very real and biological.”
No it doesn’t.
Gahaha.
The only thing I’m certain about is tall people are smart and short people are stupid (bias).
That’s interesting, just from pure speculation I would say PIQ is related to height, but not verbal IQ, as you see a lot of great philosophers and authors being short. For example, Goethe was only a bit taller than 5’6″. I think height gives a bigger brain, and height may correlate with less mutations, leading to more space for different growth in parts of the brain and better neurological functioning respectively. A lot of cognition depends on the cerebellum and it’s growth, and an assumption I would make is that taller people have larger cerebellums. You can see with basketball players, they have better muscle memory because of cerebellum growth. Remember, this is all speculation. IQs of athletes are probably higher than the rest of their racial cohorts because they have height.
Neurological functioning might be mediated by less mutational load which is probably correlated with height. Anyway, Pumpkin should do an article on Goethe. Also, to add to this word vomit and to stay on topic I would say chimps carry less mutational load than their evolutionary descendants do, as they have more stability in their genes it seems. That would be an interesting study to look at, the stability of genes across animals. I’m sure there is a lot of variation, but I think that would be mediated by social pressures of the animal. For example, there is greater variation in most animals simply for social competition.
To end this comment, I would like to ask if anyone here has heard of the Boskop Man? Pumpkin, have you heard of these legendary hominids with IQs of 150+ predicted by their 1750 cc cranial capacity?
Yes i have heard of them & they were debunked
seriously though hypothetical island hobbits and hypothetical boskop men are garbage
The Boskops were debunked. The book two neuroscientists wrote on it is funny. They use sources from the 60s. John Hawks wrote about it.
“Remember, this is all speculation”
Of course it is.
The ‘Hobbits’ exist, they’re Homo floresiensis, derived from erectus.
What do you mean, I literally have no evidence for any of this, so it would be speculation. What is your opinion, RaceRealist?
1 fossil = hobbits exist? what next, all ancient dwarves are hobbitses?
I visited the home of Goethe in Weimar, Germany during college. Everything there is named after him.
Asians are small with high PIQ. Doesn’t necessarily contradict your theory though.
a 2.5 year old can repeat one digit.
Chimps have IQ’s of (35).
But this could be a super chimp they picked.
I would like to see a chimp who grew up in poverty and had a crack cocaine addicted mother doing this test.
I always thought it was interesting that the race gap on forward digit span was so small. Any other tests with such a small gap?
Chimps have high working memory
no they dont have a high working memory. they just have an eiditic memory. animals, even the smallest of birds, have very strong visual memory power. it is also the case that preliterate humans, such as the inuit, australian aborigines, and others have stronger visual memory than do literate. perhaps the rewiring that goes on when learning to read changes the process of visual information retrieval and storage.
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