I apologize to Homo erectus

A while back I had estimated that H. Erectus had an average IQ of 55 based on the fact that they had the tool making ability of a 1979 Western seven-year-old,  but more recently I had down graded them to an IQ of 40, based on my assumption that they had the symbolic IQ of 40.

My logic was that their tool making ability only represented their spatial IQ, but a symbolic IQ of 40 dragged down their COMPOSITE IQ to 40.

Brief comment on composite IQs

Statistically naïve readers might be wondering why a spatial IQ of 55 and a symbolic IQ of 40 equals a composite IQ of 40, and not a composite IQ of 48 (the average of 55 and 40).  The answer is that IQ is just a measure of where you rank compared to neurologically normal Northwest Europeans and ranks CAN NOT be averaged to give composite rank, unless the two sub-rankings correlate perfectly.  So if you rank super low in BOTH cognitive domains, then your rank order in the COMPOSITE of both domains will be LOWER than the average of the two, because impairment at BOTH domains is so rare that it pushes your composite way down in the pecking order.  The opposite is true for people who excel in BOTH domains; their composite IQs are HIGHER than the average of each subscale.

Why the apology?

So why am I apologizing to H. erectus?  Because I was wrong to assume their symbolic IQ was only 40.  That assumption was based on the fact that they couldn’t draw AT ALL, thus suggesting they had extremely impaired understanding of symbols or representations.  People who can’t draw ANYTHING obtain an IQ of only 19 on the Draw-a-man test (corrected for old norms), however correcting for culture bias (H. erectus lived in the wild), I raised it to about IQ 40.

How did I know they couldn’t draw?  Because as far as we know, they never drew a single thing in the nearly 1.9 million years they walked the Earth.  However a friend suggested that perhaps they could draw, they just never had the IDEA of drawing.  Inventing the idea of drawing is much more difficult than drawing,  so if they never had the idea in the first place, I can’t assume they were too dumb to execute the idea.

Thus there’s no evidence that H. erectus had a symbolic IQ as low as 40, and the only hard evidence of their IQ remains their tool making ability which equates to an IQ of 55.  Since this is the only data point, I have no choice but to tentatively accept it as their IQ.  And frankly it makes a lot more sense than IQ 40, which is getting into chimpanzee territory.

How much IQ is needed to have the IDEA of drawing?

So while it takes an IQ of only 40 TO draw, how much IQ is needed to come up with IDEA of drawing, if it never existed in your world before?  If you believe in the controversial field of HBD, then perhaps the lowest IQ people in the World are the Bushmen with a genetic IQ of perhaps 72.  Yet even they appear to have come up with the idea of drawing as evidenced by their ancient rock art, so unless a more advanced people taught them this skill, then a population with a mean IQ of 72 is capable of inventing drawing.

What about Neanderthals?

So what about Neanderthals who also never drew?  Earlier I wrongly suggested this implied they too had a symbolic IQ of only 40 (commenter Melo to his credit strongly disagreed) and yet I also speculated that they must have had a much higher spatial IQ to have survived in Northern Europe.  Overall I pegged their mean IQ to be 62.

I still roughly agree with this estimate, but my logic was wrong.  Better logic is as follows:  They were more technologically advanced, more evolved, and bigger brained than H. erectus, so they probably an overall IQ above 55 (H. erectus level); yet they apparently never had the IDEA of drawing, so they were probably lower than Bushmen (perhaps genetic IQ 72 if you take HBD seriously).  Thus, splitting the difference gives an IQ of 64.

Quest for Fire: The ultimate HBD movie

[update dec 26, 2016: an earlier version of this article estimated the monkey men and cavemen to have an average IQ of 40 & 62 respectively.  I have since changed these to 55 and 64 respectively]

In the past I’ve blogged about how my fascination with HBD started after I saw the movie Quest for Fire at age five (I’m now in my thirties) because it was the first time I had a sense of different levels of human evolution, some more advanced than others, co-existing and competing in a struggle for survival.  The film uses not a word of English, so I strongly recommend it to all my readers, especially my foreign readers.  A fictional language was created for the characters and as you watch the film, you slowly pick up words, and the number of words you can learn might serve as a measure of fluid verbal IQ (as opposed to the crystalized verbal IQ measured by standard vocabulary tests).

For a film over three decades old, it remains remarkably anthropologically accurate today, as it’s now widely accepted that 80,000 years ago, several species of human did indeed co-exist.

The film shows three major levels of human evolution struggling for survival: The primitive monkey men, the cavemen, and the advanced modern humans.  .

The monkey men IQ 55

If you believe IQ is a scientifically valid concept, then the monkey men probably have an average IQ of 55, both phenotypically and genetically.  Because they were living in the wild and the natural habitat their ancestors spent thousands of years adapting to, I believe most hominins living 80.000 years ago had more or less reached their genetic potential.  The monkey men were smart enough to understand the value of fire and attack their neighboring cavemen with clubs in an attempt to steal it, but not smart enough to speak, create spears or wear clothing.

The cavemen IQ 64

The cavemen in this film probably had an average IQ of 64.  High enough to wear very crude fur coats,  fight with spears, and to speak in a language of a few hundred words.  They live in terror of being attacked by the monkey men who they call “wogaboo”.  They are smart enough use fire to cook and scare away wolves, and they are smart enough to keep the fire alive for a long period of time, but they are not smart enough to make it.

The modern humans IQ 85

The modern humans probably have an average IQ 85.  They appear to be fully modern black African type people who speak in a complex language, use throwing spears, build sturdy huts, make beautiful ceramic containers, color themselves grey, wear masks, make fire, and are even smart enough to build their village behind a pond of quicksand that traps intruders from other tribes.  Unlike other tribes, they are evolved enough to have a sense of humor and are constantly laughing at the inferior cavemen.

I doubt any population living 80,000 years ago had the genetic potential to have an average IQ above 70, so the high intelligence of this tribe was perhaps the only unrealistic thing about this movie.  Or perhaps I’m overestimating their IQs.

The film’s impact on my life

After seeing this film as a child, I remembered wishing I had lived 80,000 years ago.  Life was so exciting when he had three different levels of human evolution coexisting in a Darwinian struggle for survival.  So imagine my excitement when scholar J.P. Rushton proposed his shocking theory that Orientals were more genetically advanced than whites who were more advanced than blacks.  While the rest of the World was disgusted that Rushton could promote such horrific “pseudoscience”, I was secretly fascinated, because It was almost as if I had willed my favorite movie into life, except instead of black Africans being the most evolved  humans, as they were 80,000 years ago, Rushton was arguing that they were now at the bottom of the new tri-level hierarchy.

A beautiful love story

Aside from the anthropological value of this film, it’s one of the most romantic movies I have ever seen.  At the heart of the film is a deeply moving love story about a caveman who falls in love with a modern human woman.

Even though they speak completely different languages and arguably belong to different species, they forge an intimate bond, as she slowly teaches him how to be human.   Through her tutoring he learns what humour is and laughs for the first time in his life, and while he and his tribe know only how to have doggie style sex, she teaches him how to make love.  This films takes you back 80,000 years in time, and allows you to see the World, through the innocent eyes of the first humans, and all the awe and mystery of the endlessly uncharted landscape.



Massive brain mutation 70,000 years ago

According to eminent scholar Richard Klein, there was a massive genetic mutation that occurred in Africa that SUDDENLY made humans MUCH smarter than they had ever been before.  This mutation did not make the brain any bigger, but it did rewire it, allowing for truly symbolic thought.

According to this article:

To witness the contrast between premodern and modern ways of life, Klein says, sift through the remains from caves along the southern coast of South Africa. Simple Stone Age hunter-gatherers began camping here around 120,000 years ago and stayed on until around 60,000 years ago, when a punishing drought made the region uninhabitable. They developed a useful tool kit featuring carefully chipped knives, choppers, axes and other stone implements. Animal bones from the caves show that they hunted large mammals like eland, a horse-sized antelope. They built fires and buried their dead. These people, along with the Neanderthals then haunting the caves of Europe, were the most technologically adept beings of their time.

However, Klein says, there were just as many things they couldn’t manage, despite their modern-looking bodies and big brains. They didn’t build durable shelters. They almost never hunted dangerous but meaty prey like buffalo, preferring the more docile eland. Fishing was beyond their ken. They rarely crafted tools of bone, and they lacked cultural diversity. Perhaps most important, they left no indisputable signs of art or other symbolic thought.

Later inhabitants of the same caves, who moved in around 20,000 years ago, displayed all these talents and more.

What happened in between?

The burst of modern behavior—like other momentous happenings in our evolution—arose not in South Africa, Klein says, but in East Africa, which was wetter during the drought. Around 45,000 years ago, he believes, a group of simple people in East Africa began to behave in new ways and rapidly expanded in population and range. With better weapons, they broadened their diet to include more challenging and nutritious prey. With their new sense of aesthetic, they made the first clearly identifiable art. And they freed themselves to wander beyond the local watering hole—setting the stage for long-distance trade—with contrivances like canteens and the delicately crafted eggshell beads, which may have functioned as “hostess gifts” to cement goodwill with other clans.

Dramatic evidence of a surge in ingenuity and adaptability comes from a wave of human migration around 40,000 to 35,000 years ago. Fully modern Africans made their way into Europe, Klein says, where they encountered the Neanderthals, cave dwellers who had lived in and around Europe for more than 200,000 years. The lanky Africans, usually called Cro-Magnons once they reached Europe, were more vulnerable to cold than the husky Neanderthals. Yet they came, saw and conquered in short order, and the Neanderthals vanished forever.

Compare that with an earlier migration around 100,000 years ago, in which the Neanderthals eventually prevailed. Physically—but not yet behaviorally—modern Africans took advantage of a long warm spell to expand northward into Neanderthal territory in the Middle East, only to scuttle south again when temperatures later plunged. The critical difference between the two migrations? The earlier settlers apparently lacked the modern ability to respond to change with new survival strategies, such as fitted garments, projectile weapons and well-heated huts.

I’ve done some research and I now believe Homo Erectus had a spatial IQ of 53 and a symbolic IQ of 40, giving it a composite IQ of 41.  Then about 200,000 years ago in East Africa, it mutated into anatomically modern humans and these had a spatial IQ of 75, but a symbolic IQ of still only 40, giving them a composite IQ of 53.

So when they tried to leave Africa, they were brutally killed off by Neanderthals, who in addition to being 2.5 times stronger, had a spatial IQ of 91 and a symbolic IQ of 40, giving them a composite IQ of 62

However sometime after 70,000 years ago, anatomically modern humans mutated again in East Africa into behaviorally modern humans: their spatial IQs stayed 75 but their symbolic IQs suddenly jumped to 75 too, bringing them their composite IQ to 70.

This allowed them to leave Africa without being bullied by the Neanderthals.  The Neanderthals were still 2.5 times stronger, but modern humans were taller, faster, and now 8 points smarter.

Then after evolving to the cold climate of ice age Europe, symbolic IQ improved to 88 and spatial IQ also improved to 88, raising their composite IQs to 87, allowing them to brutally murder all the Neanderthals in record time, despite the huge difference in strength.  The super strong Neanderthals were humiliated to be destroyed by a bunch of scrawny nerdy modern humans

After the Neanderthals were killed off,  the ice age ended, and the malnutrition and disease caused brain size to shrink and composite IQ of modern Europeans to drop to 77.  However with the booming population, new high IQ genes were lifting the composite IQ up to 90.

Then in the 20th century, advances in nutrition, sanitation and vaccines, allowed them to return to pre-agriculture health, and their brains returned to their original size, and with the mutations that occurred during agriculture (see the 10,000 year explosion by Cochran and Harpending), their composite IQ was now 100.



Facts of Life IQ episode returns to youtube

Apparently when I complained about the Facts of Life IQ episode going missing from Youtube on my blog yesterday, people in high places noticed because the show has been returned:

I got the most beautiful email this morning apologizing, saying they had no idea someone as important as me was watching, and they’re so honored to have me as a fan.  I’ve printed out the email and framed it.

I’m even being sent the complete series on DVD, a poster signed by all the stars of the show, and vintage Facts of Life T-shirts.  They don’t know what size I take, so get this.  They’re sending me one in:




Not to brag, but I am Pumpkin Person.

Meanwhile here’s vintage opening theme song from the The Facts of Life.  What I love about the opening is Charlotte Rae (who played wise den mother Mrs Garrett) sings a line in the theme song itself in her loveable cackling voice, and that line is heard as her character is on screen smiling (excellent editing!)

When your books are what you’re there about

But looks are what you care about

The time is right

To learn the Facts of Life

See 0:47 in the video below:

I was so touched by the level of respect I’ve been shown that I spent the afternoon watching The Facts of Life reunion TV movie from 2001.  It was pretty cheesy in that warm fuzzy way we expect from TV chick flicks, but it was great seeing  the girls we grew up watching blossom into beautiful adult women.

Blair played by Lisa Whelchel is predictably married to some Ken doll rich guy.

Natalie, played by Mindy Cohn has grown up to be a successful journalist obsessively pursued by two good looking guys (You Go Girl!)

Tootie (aka Dorthy) played by Kim Fields has blossomed into a truly gorgeous black woman, and is working as a talk show host and aspiring actress.



Pumpkin Person’s hot chocolate recipe

Since much of North America is in the grip of a freezing weekend, I thought it’d be a good time to share my hot chocolate recipe.  I kind of copied this from a cooking show on OWN Canada (don’t know the name), but simplified it and changed it.

I love to spend winter weekends holded up at my remote lake cottage in the woods, where I put on the fire and snuggle on the couch beneath a sea of blankets, and watch a classy horror film like The Dark Hours, or an Atom Egoyan style dark drama,  or a series of a dark themed series like Six Feet Under, on a huge screen high definition TV.

And of course I need my hot chocolate on the coffee table in front of me, but not just any hot chocolate will do.  If you truly want to live like me and be part of the upper crust of the upper class, you must make your own.

You start with two chocolate bars (100 g each):  One MINTED milk chocolate, the other MINTED DARK chocolate.



You then break it into pieces and put the pieces in your hot chocolate maker.  If you can’t afford one of these, just use a pot on a stove.


Then add a cup of milk and a cup of cream (or 2 cups of half and half if you’re clever).


Then heat and mix


Until it looks like this.




A wonderful desert on a cold winter night, like tonight.

Educable (mild) Retardation on The Facts of Life

Recently I posted an episode of the sitcom The Facts of Life that dealt with IQ, but sadly the video no longer works.

The POWER of this blog is such that almost every time I post a youtube, media owners seem to suddenly realize the enormous value of their old content and remove it from youtube.

Fortunately I found the only other episode of The Facts of Life that seemed to deal with intelligence (watch it quickly before they take it off youtube ).

In this episode, all the girls at the fictional Eastland New York private school are in love with a new boy who delivers the boarding house food, but what they don’t know is he has a tragic secret.

He’s retarded.

When this leads to an awkward confrontation, the school den mother Mrs Garrett makes it all better as usual with some words of wisdom.

One of the reasons the girls on campus don’t notice the boy is retarded is that he looks normal because he has familial retardation, meaning his retardation is just part of the normal spectrum of human intelligence, unlike organic retardation which is caused by a mutation of large effect, which impairs physical appearance and brain functions beyond intelligence.

Commenter “Mug of Pee” will happily concede that organic retardation is independently genetic because it has physical symptoms, but he downplays the independent effect of genes in biologically normal IQ differences.  It would be especially interesting to find cases where familial retardates have identical twins raised from birth in very different countries, because it’s hard to imagine such an immutable disability was not hard wired into the brain.

Another amusing thing about this episode of The Facts of Life is that we’re now in season 4, so the hilarious character “Jo” is by now a regular; the writers felt the show was missing a girl from a working class background.

“Jo” played by Nancy McKeon is like a young female John Travolta in both her appearance, attitude, and tough guy Brooklyn accent.

The Facts of Life: IQ episode

The Facts of Life was a popular U.S. sitcom that originally aired on NBC from August 24, 1979, to May 7, 1988, and then the reruns continued in syndication probably well into the late 1990s so for those of us in our thirties, it was an afterschool ritual, though younger readers may have never heard of it.  I was reminded of the show because Alan Thicke just died (RIP) and he wrote the shows memorable theme song.  The show launched the career of 80s teen star Molly Ringwald and even George Clooney.

The show was about a bunch of girls attending a New York boarding school under the protective care of loveable den mother Mrs Garrett (Charlotte Rae).  The show is a throwback to a more innocent period in American life, and a simpler time, when no problem was too big to be solved by a cup of hot chocolate and a few wise words from Mrs Garrett.

It’s been decades since I’ve seen an episode, but there was one episode I could never forget.  The one where the girls at the school discover their childhood IQ scores and all the harm it does to their relationships and self-esteem.  And as usual the wise den mother Mrs Garret to the rescue.

If you have half an hour to kill, I recommend you enjoy this funny, innocent, wholesome bit of 70s television.  You’ll be glad you did:


How well does the SAT correlate with official IQ tests?

I apologize to my readers for recycling so much old material, but certain crucial issues must be resolved before we can move forward knowledgeably.

In this post, I summarize all I have learned to date about how much high SAT performers regress to the mean when faced with official IQ tests and what this implies about the SAT’s correlation with said tests.  Some of the data may contradict previous posts, as new information has come to light, causing me to revise old numbers.

Study I: New SAT vs the Raven

A study by Meredith C. Frey and Douglas K. Detterman found a 0.48 correlation between the re-centered SAT and the Raven Progressive Matrices in a sample of 104 university undergrads, but after correcting for range restriction, they estimate the correlation to be 0.72 in a less restricted sample of college students.  I don’t buy it, but I’m not interested in how well the re-centred SAT would correlate with the Raven among college students, but among ALL American young adults. (including the majority who never took the SAT).

Using the Frey and Detterman data, I decided to look at the Raven scores of those who scored 1400-1600 on the re-centred SAT, because 1500 on the new SAT (reading + math) corresponds to an IQ of 143 (U.S. white norms), which is 46 points above the U.S. mean of 97. Now if the new SAT correlated 0.72 or higher among ALL American adults, we’d expect their Raven scores to only regress to no less than 72% as far above the U.S. mean, so 0.72(46) + 97 = IQ 130.

I personally looked at the scatter plot carefully and did my best to write down the RAPM IQs of every single participant with an SAT score from 1400-1600. This was an admittedly subjective and imprecise exercise given how small the graph is, but I counted 38 top SAT performers and these were their approximate RAPM IQs: 95, 102, 105, 108, 108, 110, 110, 113, 113, 113, 113, 113, 117, 117, 117, 117, 117, 120, 120, 120, 122, 122, 128, 128, 128, 128, 134, 134, 134, 134, 134, 134, 134, 134, 134, 134, 134, 134


The median IQ is 120, and it does not need to be converted to white norms because the Raven was normed in lily white Iowa circa 1993, but as commenter Tenn noted, I should have perhaps corrected for the Flynn effect since the norms were ten years old at the time of the study.  Correcting for the Flynn effect reduces the median to 118 (U.S. white norms) which is 21 points above the U.S. mean of 97.

For people who are 46 IQ points above the U.S. mean on the new SAT to regress to only 21 points above the U.S. mean, suggests the new SAT correlates 21/46 = 0.46 with the Raven in the general U.S. population.

Study II: New SAT vs the abbreviated WAIS-R

Harvard is the most prestigious university in the World with an average SAT score in the stratosphere, thus it’s interesting to ask how Harvard students perform on an official IQ test. The best data on the subject was obtained by Harvard scholar Shelley H Carson and her colleagues who had an abbreviated version of the WAIS-R given to 86 “Harvard undergraduates (33 men, 53 women), with a mean age of 20.7 years (SD 3.3)… All were recruited from sign-up sheets posted on campus. Participants were paid an hourly rate…The mean IQ of the sample was 128.1 points (SD 10.3), with a range of 97 to 148 points.”

It should be noted however that the WAIS-R was published in 1981, and that the norms were collected from 1976 to 1980. Carson’s study was published in 2003, so presumably the test norms were 25 years old.

James Flynn cites data showing that from WAIS-R norms (circa 1978) to WAIS-IV norms (circa 2006) the vocabulary and spatial construction subtest (used in the abbreviated WAIS-R) increased by 0.53 SD and 0.33 SD respectively. These gains would result in the composite score of the abbreviated WAIS-R becoming obsolete at a rate of 0.26 IQ points per year, meaning the Harvard students’ scores circa 2003 were 6.5 points too high. This reduces the mean IQ of the sample to 121.6 (U.S. norms) which is about 120 (U.S. white norms); 23 points above the U.S. mean of 97 (white norms).

However Harvard’s median re-centered SATs of 1490 equate to IQ 143 (U.S. white norms) which is 46 points above the U.S. mean of 97.  Assuming the sampled Harvard students were cognitively representative of Harvard and assuming Harvard is cognitively representative of all 1490 SAT Americans, the fact they regressed from being 46 IQ points above average on the SAT to 23 IQ points above average on the abbreviated WAIS-R, suggests the re-centered SAT correlates 23/46 = 0.5 with the abbreviated WAIS-R.

Study III:  Old SAT vs the full original WAIS

Perhaps the single best study was referred to me by a commenter named Andrew.  In this study, data was taken from the older more difficult SAT, and participants took the full-original WAIS.  In this study, six samples of  seniors from  the extremely prestigious Dartmouth (the 12th most selective university in America) averaged 1357 on the SAT just before 1974. Based on my latest research, an SAT score of 1357 circa 1974 would have equated to an IQ of 144 (U.S. norms); 143 (U.S. white norms).  Because this is much higher than previously thought; the degree of regression is quite devastating.

Assuming these students are typical of high SAT Americans, it is interesting to ask how much they regress to the mean on various subtests of the WAIS.

Averaging all six samples together, and then adjusting for the yearly Flynn effect from the 1950s through the 1970s (see page 240 of Are We Getting Smarter?) since the WAIS was normed circa 1953.5 but the students were tested circa 1971.5, then converting subtest scaled scores to IQ equivalents, in both U.S. norms and U.S. white norms (the 1953.5 norming of the WAIS included only whites), we get the following:

iq equivalent (u.s. norms) iq equivalent (u.s. white norms) estimated correlation with sat in the general u.s. population inferred from regression to the mean from SAT IQ 44 points above U.S. mean.
sat score 144 143 44/44 = 1.0
wais information 128.29 127.2 28.29/44 = 0.64
wais comprehension 122.22 120.9 22.22/44 = 0.51
wais arithmetic 120.37 119 20.37/44 = 0.46
wais similarities 119.16 117.75 19.16/44 = 0.44
wais digit span 117.37 115.9 17.37/44 = 0.39
wais vocabulary 125.93 124.75 25.93/44 = 0.59
wais picture completion 105.87 104 5.87/44 = 0.13
wais block design 121.82 120.5 21.82/44 = 0.50
wais picture arrangement 108.33 106.55 8.33/44 = 0.19
wais object assembly 113.65 112.05 13.65/44 = 0.31
wais verbal scale 126 125 26/44 = 0.59
wais performance scale 116 114 16/44 = 0.36
wais full-scale 123 122 23/44 = 0.52


In three different studies (New SAT vs Raven, New SAT vs abbreviated WAIS-R, Old SAT vs WAIS), people averaging exceptionally high SAT scores averaged only 46%, 50%, or 52%, respectively, as far above the U.S. mean on the official IQ tests as they did on the SAT, suggesting the SAT (old or new), only correlates about 0.5 with official IQ tests.  Correlations in the range of 0.5 are about all you’d expect most educational measures (school grades, years of school) to correlate with IQ, but it’s a surprisingly low correlation given that some consider the SAT to be more than a mere education measure, but an IQ test itself.  So either the SAT is NOT equivalent to an IQ test, or it’s only equivalent to an IQ test among people with similar educational backgrounds, or my method of inferring correlations from the degree of regression is giving misleading results (perhaps because Spearman’s Law of Diminishing Returns is flattening the regression slope at high levels or because of ceiling bumping on the tests involved).

The potentially low correlation between the SAT (and presumably other college admission tests like the GRE, LSAT, etc) with official IQ has some positive implications.  It means that to whatever extent IQ and success are correlated in America, the correlation is a natural consequence of smart  people adapting to their environment, and not the artificial self-fulfilling prophecy of a man-made testocracy.

It also suggests that there’s no substitute for a real IQ test given by a real psychologist with blocks, cartoon pictures, jig-saw puzzles, and open-ended questions.  I can see David Wechsler, chuckling from the grave, saying “I told you so.”

Converting pre-1995 SAT scores to IQ yet again

Many high IQ societies accept specific scores from the pre-1995 SAT for admission, as if all SATs taken before the infamous recentering in April 1995 had the same meaning.  And yet Mensa, which only accepts the smartest 2% of Americans on a given “intelligence test” makes a curious distinction.  Prior to 9/30/1974, you needed an SAT score of 1300 to get into Mensa, yet from 9/30/1974 to 1/31/1994, you needed a score of 1250.

Well, that’s odd I thought, since all SAT scores from the early 1940s to 1994 are supposedly scaled to reflect the same level of skill, why did it suddenly become 50 SAT points easier to be in the top 2% in 1974?  And if such an abrupt change can occur in 1974, why assume stability every year before and since?  It didn’t make any sense.

And I wasn’t the only one who was wondering.  Rodrigo de la Jara, owner of iqcomparisonsite.com, writes:

If someone knows why they have 1300 for scores before 1974, please send an email to enlighten me.


The mean verbal and math SAT scores, if ALL U.S. 17-year-olds had taken the old SAT

To determine how the old SAT maps to IQ I realized I couldn’t rely on high IQ society cut-offs.  I need to look at the primary data.  Now the first place to look was at a series of secret studies the college board did in the 1960s, 1970s, and 1980s.  These studies gave an abbreviated version of the SAT to a nationally representative sample of high school juniors.  Because very few Americans drop out of high school before their junior year, a sample of juniors cam close to representing ALL American teens, and then scores were statistically adjusted to show how virtually ALL American teens would average had they taken the SAT at 17. The results were as follows (note, these scores are a lot low than the actual mean SAT scores of people who take the SAT, because they also include all the American teens who usually don’t):


Chart I: taken from page 422 of The Bell Curve (1994) by Richard J. Herrnstein and Charles Murray: Estimated mean verbal and math SATs by year, if all U.S. 17-year-olds had took the SAT, not the college bound elite only.

The verbal and math standard deviations if ALL U.S. 17-year-olds had taken the old SAT

 Once I knew the mean SAT scores if ALL American teens had taken the SAT at 17 in each of the above years, I needed to know the standard deviations.   Although I knew the actual SDs for 1974, I don’t know them for other years, so for consistency, I decided to use estimated SDs.

According to the book The Bell Curve, since the 1960s, virtually every single American teen who would have scored 700+ on either section of the SAT, actually did take the SAT (and as Ron Hoeflin has argued, whatever shortfall there’d be would be roughly balanced by brilliant foreign test takers).  This makes sense because academic ability is correlated with taking the SAT, so the higher the academic ability, the higher the odds of taking the SAT, until at some point, the odds likely approach 100%.

Thus if 1% of all American 17-year-olds both took the SAT and scored 700+ on one of the subscales, then we know that even if 100% of all U.S. 17-year-olds had taken the SAT, still only 1% would have scored 700+ on that sub-scale.  By using this logic, it was possible to construct a graph showing what percentage of ALL U.S. 17-year-olds were capable of scoring 700+ on each sub-scale, each year:


Chart II: taken from page 429 of The Bell Curve (1994) by Richard J. Herrnstein and Charles Murray

What the above graph seems to show is that in 1966, a verbal score of 700+ put you in about the top 0.75% of all U.S. 17-year-olds, in 1974 it put you around the top 0.28%, in 1983 about the top 0.28% and in 1994 about the top 0.31%.

Similarly, scoring 700+ on math put you around the top 1.25% in 1966, the top 0.82% in 1974, the top 0.94% in 1983, and the top 1.52% in 1994.

Using the above percentages for each year, I determined how many SDs above the U.S. verbal or math SAT mean (for ALL 17-year-olds) a 700 score would be on a normal curve, and then divided the difference between 700 and each year’s mean (Chart I) by that number of SDs, to obtain the estimated SD. Because Chart I did not have a mean national score for 1994, I assumed the same means as 1983 for both verbal and math.  This gave the following stats:


Chart III: Estimated means and SD for the pre-re-centered SAT by year, if all U.S. 17-year-olds had taken the SAT, not just the college bound elite

Calculating verbal and math IQ equivalents from the old SAT

Armed with the stats in chart III, it’s very easy for people who took the pre-recentered SAT to convert their subscale scores into IQ equivalents.  Simply locate the means and SDs from the year closest to when you took the PRE-RECENTERED SAT, and apply the following formulas:

Formula I

Verbal IQ equivalent (U.S. norms)  = (verbal SAT – mean verbal SAT/verbal SD)(15) + 100

Formula II

Math IQ equivalent (U.S. norms) =  (math SAT – mean math SAT/math SD)(15) + 100


Calculating the mean and SD of the COMBINED SAT if all U.S. 17-year-olds had taken the test

Now how do we convert combined pre-recentered SATs (verbal + math) into IQ equivalents.  Well it’s easy enough to estimate the theoretical mean pre-recentered SAT for each year by adding the verbal mean to the math mean.  But estimating the standard deviation for each year is trickier because we don’t know the frequency for very high combined scores for each year, like we do for sub-scale scores (see Chart II).  However we do know it for the mid 1980s. Ron Hoeflin claimed that out of a bit over 5,000,000 high-school seniors who took the SAT from 1984 through 1988, only 1,282 had combined scores of 1540+.

Hoeflin has argued that even though only a third of U.S. teens took the SAT,  virtually 100% of teens capable of scoring extremely high on the SAT did so, and whatever shortfall there might be was negated by bright foreign test-takers.

Thus, a score of 1540+ is not merely the 1,282 best among 5 million SAT takers, but the best among ALL fifteen million Americans who were 17 years-old anytime from 1984 through 1988.  In other words, 1540 was a one in 11,700 score, which on the normal curve, is +3.8 SD.  We know from adding the mean verbal and math for 1983 in Chart I, that if all American 17-year-olds had taken the SAT in 1983, the mean COMBINED score would have been 787, and if 1540 is +3.8 SD if all 17-year-olds had taken it, then the SD would have been:

(1540 – 787)/3.8 = 198

But how do we determine the SD for the combined old SAT for other years?  Well since we know the estimated means and SD of the subscales, then Formula III is useful for calculating the composite SD (from page 779 of the book The Bell Curve by Herrnstein and Murray):


Formula III

r is the correlation between the two tests that make up the composite and σ is the standard deviation of the two tests.

However Formula III requires you to know the correlation between the two subscales.  Herrnstein and Murray claim that for the entire SAT population, the correlation between SAT verbal and SAT math is 0.67 however we’re interested in the correlation if ALL American young adults had taken the old SAT, not just the SAT population.

However since we just estimated that the SD of the combined SAT if all 17-year-olds took the SAT in 1983 would have been 198, and since we know from Chart III that the 1983 verbal and math SDs if all 17-year-olds had taken the SAT would have been 116 and 124 respectively, then we can deduce what value of r would cause Formula III to equal the known combined SD of 198.  Shockingly, that value is only 0.36!

Now that we know the correlation between the verbal and math SAT if all U.S. 17-year-olds had taken the SAT would have been only 0.36 in 1983, and if we assume that correlation held from the 1960s to the 1990s, using the sub-scale SDs in chart III, we can apply Formula III to determine the combined SDs for each year, and of course the combined mean for each year is just  the sum of the verbal and math means in chart III.


Chart IV: Estimated means and SDs of the combined pre-recentered SAT if all U.S. 17-year-olds had taken the test


Calculating full-scale IQ equivalents from the old SAT

Armed with the stats in Chart IV, it’s very easy for people who took the pre-recenetered SAT to convert their COMBINED scores into IQ equivalents.  Simply locate the means and SDs from the year closest to when you took the PRE-RECENTERED SAT, and apply the following formula:

Formula IV

Full-scale IQ equivalent (U.S. norms)  = (combined SAT – mean combined SAT/combined SD)(15) + 100

*Note: the IQ equivalent of SAT scores above 1550 or so will be underestimated by this formula because of ceiling bumping.

Was Mensa wrong?

Based on chart IV, it seems Mensa is too conservative when it insists on SAT scores of 1300 prior to 9/30/1974 and scores of 1250 for those who took it from 9/30/1974 to 1/31/1994.  Instead it seems that the Mensa level (top 2% or + 2 SD above the U.S. mean) is likely achieved by scores of 1218 for those who took the SAT close to 1966, and only 1170 for those who took it closer to 1974.  For those who took the pre-recentered SAT closer to 1983 or 1994, it seems Mensa level was achieved by scores of 1183 and 1203 respectively.

Of course all of my numbers assume a normal distribution which is never perfectly the case, and it’s also possible that the 0.36 correlation between verbal and math I found if all 17-year-olds took the SAT in 1983 could not be generalized to other years, so perhaps I’m wrong and Mensa is right.  But it would be nice to know how they arrived at their numbers.

The black-white IQ gap

From about 1917 to 2006, large representative samples of American black adults have scored about one standard deviation below American white adults on the type of verbal and performance IQ tests first created for screening WWI recruits, and later borrowed by David Wechsler to use in his wildly popular scales; considered the gold standard in the field.

Although the black-white test score gap has shrunk somewhat on more scholastic tests where it used to be absurdly high, the longevity and consistency of the gap on the most conventional and respected of official IQ tests has led some to conclude that it is mostly or entirely genetic.

The single most powerful piece of supporting evidence for the genetic hypothesis is the Minnesota Transracial adoption study in which white, black and mixed-race kids were raised from early childhood in white upper-class homes.  Although the adopted white and black kids scored well above the national white and black means (corrected for outdated norms) of about 102 and 86 respectively (U.S. norms)  in childhood (though not at 17), large racial IQ gaps were found among the adopted kids at both ages.


However the study had a problem, as explained by its authors Scarr and Weinberg (1976):

It is essential to note, however, that the groups also differed significantly (p < .05) in their placement histories and natural mother’s education. Children with two black parents were significantly older at adoption, had been in the adoptive home a shorter time, and had experienced a greater number of preadoption placements. The natural parents of the black/black group also averaged a year less of education than those of the black/white group, which suggests an average difference between the groups in intellectual ability. There were also significant differences between the adoptive families of black/black and black/white children in father’s education and mother’s IQ.[1]

Because the children with two black biological parents were adopted later than the children with only one black biological parent, it’s best to exclude them from our analysis and focus only the IQ gap between the adopted kids with two white biological parents and those with one black and one white biological parent.  Not only were both these groups adopted early into white upper-class homes, but since both had white biological mothers, both enjoyed the benefits of a white prenatal environment.  What the study found was that by age seven, the fully white kids average IQ 111.5 and the half-black kids averaged 105.4, a difference of 6.1 points (see chart above).

This difference may sound small, but keep in mind that we are not comparing full-blooded blacks to full-blooded whites, we are comparing half-African Americans to full-blooded whites.  Also keep in mind that because everyone is being raised in the same social class, and social class independently explains such a large percent of the IQ variance at age seven, the entire IQ scale becomes compressed, so instead of the white standard deviation being about 14.5 (U.S. norms), it is only 11.3 in these adopted white kids.  Thus a 6.1 point gap should be thought of as a 0.54 SD gap since 6.1/11.3 = 0.54.

So if kids with one black parent score 0.54 SD below white kids when both are raised in upper class homes and both have white prenatal environments, that 0.54 SD gap is arguably 100% genetic.  And if having one black parent causes a 0.54 SD genetic drop in IQ, then having two black parents should cause a 1.08 SD genetic drop in IQ (note that the national black-white IQ gap in adults has been about 1 SD since WWI).

Failure to replicate

Now before HBDers get too excited, one should remember that the Minnesota transracial adoption study has never been replicated and that three other similar studies failed to find much of any black < white IQ gap, with some even showing the opposite pattern.

Tizard (1974) compared black, white and mixed-race kids raised in English residential nurseries and found that the only significant IQ difference favored the non-white kids. A problem with this study is that the children were extremely young (below age 5) and racial differences in maturation rates favor black kids. A bigger problem with this study is that the parents of the black kids appeared to be immigrants (African or West Indian) and immigrants are often hyper-selected for IQ (see Indian Americans).

A second study by Eyferth (1961) found that the biological illegitimate children of white German women had a mean IQ of 97.2 if the biological father was a white soldier and 96.5 if the biological father was a black soldier (a trivial difference). Both the white and mixed kids were raised by their biological white mothers. One problem with this study is that the biological fathers of both races would have been screened to have similar IQs because at the time, only the highest scoring 97% of whites and highest scoring 70% of blacks passed the Army General Classification Test and were allowed to be U.S. soldiers. In addition, 20% to 25% of the “black fathers” were not African-American or even black Africans, but rather French North Africans (dark caucasoids as we define them here).

A third study by Moore (1986) included a section where he looked at sub-samples of children adopted by white parents. He found that nine adopted kids with two black biological parents averaged 2 IQ points higher than 14 adopted kids with only one biological black parent.  A 2 point IQ gap sounds small, but as I mentioned above, the IQ scale is compressed in kids when everyone is raised in the same social class (which might have been the case in this study), so a 2 point gap becomes 0.18 of the compressed white SD.

The results of this study suggest that half-white kids are 0.18 SD genetically duller than black kids, which predicts that fully white kids are 0.36 SD genetically duller than black kids.  One problem with this study is that the black kids would have had black prenatal environments while many, or all, of the half-white kids would have had white prenatal environments, but given the low birth weight of black babies, if anything this suggests the genetic IQ gap favoring blacks is even larger than 0.36 SD!


We have two quality studies: The Minnesota Transracial adoption study (when black kids are excluded because of confounds) and Moore (1986).  The first study implies U.S. black genes reduce IQ by 1.04 SD in kids (-1.04 SD), while the second implies U.S. black genes increase IQ by 0.36 SD in kids (+0.36 SD).  But the first analysis was based on comparing 55 mixed kids to 16 white kids (total n = 71), while the second analysis was based on comparing nine black kids with 14 mixed kids (total n = 23).  The total n of both studies combined is 94, so the first study provided 76% of the total sample while the second study provided 24%, thus the best I can do is just weigh these two conflicting results by sample size:

Effect of black genes on childhood IQ = 0.76(-1.04 SD) + 0.24(+0.36 SD)

Effect of black genes on childhood IQ = -0.79 SD + 0.09

Effect of black genes on childhood IQ = -0.7 SD

What this suggests is that on a scale where the white genetic IQ is set at 100 with an SD of 15, the U.S. black genetic IQ is 90, at least in childhood (in adulthood it may be around 85 since some IQ genes might not exert influence until post-puberty).  This is consistent with the fact that despite half a century of affirmative action, the average black IQ (when expressed with reference to white norms) remains below 90 in both children and adults (see charts below).

On the other hand, my estimate is based on only two studies with a combined sample of only 71 adopted kids and we can only assume (based on education when known) that the IQs of their biological parents are roughly racially representative.  And although the black-white IQ gap in adults has apparently changed not at all since WWI, the environmental gap might not have changed that much either.  Despite decades of affirmative action, the median wealth for white families in 2013 was around $141,900, compared to Hispanics at about $13,700 and blacks at about $11,000 so even in the age of a black President, environmental factors can’t be ruled out.


Black white IQ gap in the Wechsler Intelligence Scale for Children in the nationally representative samples used to norm each edition:

white iq (u.s. norms) black iq (u.s. norms) white iq (white norms) black iq (white norms) black-white iq gap (u.s. norms) black-white iq gap (white norms)
wisc-r (1972) 102.3 (sd = 14.08) 86.4 (sd = 12.63) 100 (sd = 15) 83 (sd = 13.46) 15.9 17
wisc-iii (1989) 103.5 (sd = 13.86) 88.6 (sd = 12.83) 100 (sd = 15) 84 (sd = 13.89) 14.9 16
wisc-iv (2002) 103.2 (sd = 14.52) 91.7 (sd = 15.73) 100 (sd = 15) 88 (sd = 16.25) 11.5 12
wisc-v (2013) 103.5 (sd = 14.6) 91.9 (sd = 13.3) 100 (sd = 15) 88 (sd = 13.66) 11.6 12

Black white IQ gap in the Wechsler Adult Intelligence Scale in the nationally representative samples used to norm each edition:

white iq (u.s. norms) black iq (u.s. norms) white iq (white norms) black iq (white norms) black-white iq gap (u.s. norms) black-white iqgap (white norms)
wais-r (1978) 101.4 (sd = 14.65) 86.8 (sd = 13.14) 100 (sd = 15) 85 (sd = 13.45) 14.6 15
wais-iii (1995) 102.6 (sd = 14.81) 89.1 (sd = 13.31) 100 (sd = 15) 86 (sd = 13.48) 13.5 14
wais-iv (2006) 103.4 (sd = 14) 87.7 (sd = 14.4) 100 (sd = 15)  83 (sd = 15.43) 15.7  17


Sources for charts:

WISC-R, WISC-III, and WISC-IV U.S. norms, from pg 27 (Table A1) of Black Americans Reduce the Racial IQ Gap: Evidence from Standardization Samples by William T. Dickens & James R. Flynn

WAIS-IV U.S. norms from pg 190 of WAIS-IV, WMS-IV, and ACS: Advanced Clinical Interpretation edited by James A. Holdnack, Lisa Drozdick, Lawrence G. Weiss, Grant L. Iverson

WISC-V U.S. norms from page 157, table 5.3 of WISC-V Assessment and Interpretation: Scientist-Practitioner Perspectives By Lawrence G. Weiss, Donald H. Saklofske, James A. Holdnack, Aurelio Prifitera