Have we recovered our paleolithic brain size yet?

Although brain size roughly tripled as humans evolved from apes, one mystery is the little known brain shrinkage that occurred in the last 10,000 years or so.   The bulk of the evidence for this comes from Maciej Henneberg who published the following table:

cranialcapacityovertime

Source:  Henneberg, 1988

One problem with this table is that cranial capacity is not measured directly by actually filling the skull with mustard seeds, water or beads etc, but rather by using regression equations which may or may not apply to all samples.

However there’s also evidence from directly measured cranial capacity suggesting brains have shrunk since the upper paleolithic.

directlymeasuredcranialcapacity.PNG

Source:  Henneberg, 1988

So it seems that brain size had been shrinking since the stone age until at least the industrial revolution;  the question is what’s happened since?

According to Richard Lynn, brain size has since been increasing because of better health and nutrition,  and this is matched by a similar increase in IQ test performance, known as the Flynn effect.

Unfortunately I don’t know of any directly measured cranial capacities from 21st century young adults.  The closest we have are MRI scans of intracranial volume, but one scientist working in this field recently told me that these can give different results depending on the scanning (MRI) machine and the algorithms used.  For more details, see here and here.

Thus, I turn once again to the Lee and Pearson regression formulas, for estimating cranial capacity from external head measures which Lee and Pearson found agreed with the direct packing method far better than the packing method applied by two different packers!

cranialcapacity

Using 2012 anthropometric data from the U.S. army,  I found that men have a head length, head breadth and head height of 199.5 mm, 154.3 mm and 131.1 mm respectively.  Comparable figures for women are 189.8 mm, 147.8 mm, and 126.5 mm.

Assuming these forumulas are still valid today,  21st century U.S. army men average 1499 cc and their female counterparts average 1337 cc, for a sex-combined average of 1418 cc.

The simplest explanation for the fall and recent rise of brain size is the one advanced by Richard Lynn.  As humans switched from hunting to farming, malnutriton and disease caused brain size (and height) to plummet,  but with 20th century advances in health and nutrition, First World countries have (largely) recovered our former brain size.

But why is the 2012 U.S. army sample still 80 cc lower than people 50 to 30 kya?  I see four reasons:

  • Most of the upper paleolithic samples are probably from Europe, while the U.S. army is more diverse.
  • The U.S. army is slightly shorter than their civilian  counterparts, and so their heads might be slightly smaller.
  • Even in 2012, much of the U.S. still suffered from sub-optimum nutrition and inadequate health care during their prenatal and perinatal development.
  • Upper paleolithic people may have been genetically (if not phenotypically) more robust than people today. For example Richard Klein once claimed that if a paleolithic (but anatomically modern) human walked into the room, the only thing we’d notice about him is that he was extraordinarily well built.  Among 1989 army personnel of the same rank, race, and sex, weight correlates 0.41 with cranial capacity (at least as estimated by the Lee & Pearson formula).  Among the entire army, it correlated 0.66.  Thus, there may have been a slight genetic decrease in brain size related to body size, but the lion’s share of the decrease and all of the increase was likely health and nutrition.
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Predicting your height or IQ from your DNA

Steve Hsu writes about his recent research predicting height from DNA with stunning accuracy:

Had we taken a poll on the eve of releasing our biorxiv article, I suspect 90+ percent of genomics researchers would have said that ~1 inch accuracy in predicted human height from genotype alone was impossible.

heightfromgenotype

Source:  http://infoproc.blogspot.com/2018/08/scientists-of-stature.html

In the comment section I wrote the following:

This is absolutely brilliant research and in some ways it’s even more important than predicting IQ because height is a person’s most salient property and the most important datum police use in finding suspects.

Now that you have proven you can strongly predict height within a specific time and place (21st century Western countries), the next step is predicting the CAUSAL component of height, by building an algorithm that can predict height in ANY time and place. The scientific standard for proving A causes B seems to be that A precedes B in time and A correlates with B in all times and places. We know for example that the Y chromosome causes height because it precedes the development of height in time and because people with Y chromosomes are taller than those without it in virtually all countries and all centuries, so we know it’s not just some local interaction causing a spurious correlation.

So it would be even more fascinating and useful if your team had the computer learn how to predict heights on a global sample (i.e. a mix of people living in Europe, Asia, and Africa) since you have access to data from all of these continents. Now there would be a much larger margin of error because of the enormous differences in health and nutrition, but to help with this, I would enter the Human Development Index (HDI) of the country each individual was from.

The result would be an algorithm that could predict the height of anyone anywhere using just SNPs and HDI and because the predictor would work everywhere and everywhen, it would not just be correlative, but causal. It would prove the genome and HDI each have an INDEPENDENT (i.e. causal) effect on height. The advantage of causal predictors is not just that it would debunk the skeptics, but it might even allow you to predict the height someone living 40,000 years ago would have had he been born and raised in 21st century America (by entering modern America’s HDI into the formula)

The same type of study could also be done for IQ if you had a highly g loaded IQ test that was sufficiently culture reduced to compare people in First and Third World countries. Such a universal algorithm might even be used to estimate the IQ Neanderthals, Cromagnons or Denisovans would have if they were born and raised in 21st century America (assuming comparable genomic architecture)

Increasing head size in U.S. men: 1966 to 2012

To further test Richard Lynn’s theory that the Flynn effect is caused by nutrition and health increasing the size and functioning of the brain, I compared the U.S. army’s anthropometric data from 1966 with data from 2012, looking  for evidence of brain growth since the Vietnam war.  My source for the 1966 and 2012 data are THE BODY SIZE OF SOLDIERS _ U.S. Army Anthropometry-1966 and 2012 ANTHROPOMETRIC SURVEY OF U.S. ARMY PERSONNEL: METHODS AND SUMMARY STATISTICS respectively.

Adult male head circumference 1966

headcircumference1960s

Adult male head circumference 2012

headcircumferenceusmen2012

 

Adult male head length in 1966

headlength1960s

Adult male head length in 2012

headlengthmale2012

Adult male head breadth in 1966

headbreadth1960s

 

Adult male head breadth in 2012

headbreadthmen2012

Adult male head height in 1966

headheight1960s

 

Adult male head height in 2012

headheightmen2012

Discussion

By 1966 standards,adult male U.S. head circumference, head length, and head breadth increased by 0.83, 0.66, and 0.27, standard deviations (SDs) respectively, though head height seems to have decreased by 0.12 SD (sampling error?).  On average adult male head size measures have increased by 0.41 SD, however a study by JC Wickett et al found that head circumference was the single best predictor of brain size, and head height may even be negatively correlated with IQ, though given the small sample size, it’s important not to over-interpret this.

braincorrelation

According to James Flynn, performance on U.S. IQ tests has been increasing by 3 point per decade since the earliest days of testing.  This would suggest an IQ increase of 13.8 points from 1966 to 2012 or about 0.92 SD.  This is only slightly more than the 0.83 SD increase in head circumference over the same period.  And army data may slightly underestimate the head size increases because in 1966, even sons of the elite were often forced to join the army because of the draft, while in 2012, the poor and non-white have been forced to do more than their fair share of army service.  Adjusting for demographic changes in the U.S. army, the head circumference increase might perfectly match the IQ increase.

 

Increase in U.S. head circumference: 1978 to 1991

I found some novel data to test Richard Lynn’s theory that the Flynn effect is caused by better nutrition improving the size and functioning of the brain.  CDC head circumference data from circa 1978 and circa 1991.  Although head circumference is only a rough proxy for brain size in adults, it’s an excellent proxy in young children, correlating as much as 0.93.

Circa 1978 data (sorry it’s hard to read):

headcirc70s

Circa 1991 (data)

headcircumference1988to1994

I ignored children under age 1 because the age categories for these were not comparable in both eras.  But for ages one through seven I found the following increases in U.S. head circumference from circa 1978 to circa 1991 (expressed in 1978 standard deviation units).

1 year:  +0.12 SD (males) +0.29 SD (females)

2  years: +0.24 SD (males) +0.28 SD (females)

3 years: +0.21 SD (males) +0.47 SD (females)

4 years: +0.19 SD (males) +0.06 SD (females)

5 years: +0.29 SD (males) +0.53 SD (females)

6 years: +0.22 SD (males) +0.17 SD (females)

7 years: +0.35 SD (males) +0.3 SD (females)

Amazingly, there was an increase for all 14 age sex categories.  You would think just by sampling error I’d get at least one decrease or at least no change, but no.  This proves the head circumference increase is a real phenomenon.

Averaging across both sexes and all age groups, the increase was 0.27 SD from circa 1978 to circa 1991 or 0.21 SD a decade.   Performance on childhood U.S. IQ tests like the WISC has also increasing by 0.2 SD (3 IQ points) per decade since the test was first published in 1949.

Coincidence?

It’s strange to think that in a country as rich as America, the average person was malnourished to the point of brain damage as recently as the 1970s,  but when I watch old clips from Donahue or some my favorite 1970s slasher films,  I can kind of see it.

The interesting question is whether the entire Flynn effect is a biological gain in real intelligence (as Richard Lynn believed it to be, with a few exceptions) or whether it’s only about 40% biological as Arthur Jensen believed (citing a roughly 0.4 correlation between IQ and brain size) with the remaining 60% being test sophistication caused by culture.  Or as James Flynn himself has argued, is the distinction between real intelligence and culturally acquired skills a false dichotomy?

Oprah vs Ellen: Cranial Capacity

As commenter pumpkinhead noted, the following formula is used to calculate cranial capacity in living people.

cranialcapacity

Source J.P. Rushton

This regression equation is over 100 years old so it may underestimate the crania of people today,  though if everyone in the modern developed world is underestimated to a similar degree, it might still be useful for measuring relative differences.

It’s very hard to compare the cranial capacity of two people just from looking at photos because as commenter pumpkinhead has noted, small differences in closeness to the camera can distort the relative sizes.  Nonetheless when two people are sitting behind the same desk,  you might get more reasonable results.

ellen

Putting a ruler on my computer screen, it seems that Oprah’s cranium is 1.205 as long as Ellen’s.

headlength2

 

And 1.26 times as high.

 

 

To determine head breadth, we need a photo where they’re both facing the camera.

ellen3

From here it seems Oprah’s head breadth is 1.017 times as great as Ellen’s.

 

 

The following are actual head dimensions from the U.S. military.

headcircumference

If we conservatively assume a woman as intelligent as Ellen has the head dimensions of just the average white woman (L: 186 B: 144 H: 124:) then Oprah should have the following dimensions: L: 224 B: 146 H: 156

This gives Oprah a cranial capacity of 1874 cc (1.48 times as big as the average white woman’s) using the Lee and Pearson formula, but given the huge error that can occur from trying to measure photographs,  I could be off by as much as 100 cc.  Commenter pumpkinhead doubts she is beyond the mid 1700s.

Open thread: No straw with my drink

PLEASE POST ALL OFF-TOPIC COMMENTS IN THIS THREAD.  THEY WILL NOT BE POSTED IN THE MAIN ARTICLES

driving

Lauren Ambrose

My coworkers and I were at lunch and the server looked like Lauren Ambrose from my favorite show Six Feet Under.

When I requested a straw for my Ice Tea, she told me there was a no-straw policy because they are trying to help the Oceans, but if I wanted one she would get it.

“If you don’t mind,” I said.

Apparently she did mind, because the straw never came, but other than that the service was great.

I decided to say nothing because I didn’t want her to think I didn’t care about the safety of the fish.

It occurred to me that she must be low on psychopathy to have risked such a large tip just to defend the fish.

Had HBD Chick and her fan Jayman been there, they would have perhaps thought it was because she is Nordic, and Northwestern Europeans are more genetically moral because of a lack of cousin marriage.

 

Independent confirmation of Oprah’s head size

 

jordan

Oprah and the enormous Michael Jordan go head to head

Perhaps the most famous person to doubt Oprah’s head size was Stephen Spielberg.  When he cast her to be in The Colour Purple, Oprah tried to warn him that finding a wig would be impossible but Spielberg, having worked with some of the biggest headed men in show business, was having none of it, believing Oprah’s head would easily fit into their jumbo sized wigs.  He couldn’t have been more wrong, according to this quote from Oprah in the May 14, 1996 National Enquirer.

enquier2

 

Of course Oprah knew wigs were a problem from when she went bald back in Baltimore (from the same article).

enquirer

Independent confirmation for Oprah’s colossal cranium comes from an internet comment by a David Letterman fan named Helen Read who on Dec 6, 2007 reported that Letterman was told that Oprah has a hat size of 8.

Oprahhead

 

Since hat size equals the diameter of a perfectly spherical head, dividing circumference by pi (3.14) gives hat size, thus a hat size of 8 perfectly corroborates her 25.25″ head.

hatsize

 

The late Gene Siskel went hat shopping with Oprah and the salesman said Oprah’s was the largest head he’d ever seen.

Using the late J.P. Rushton’s idea of using the formula for calculating the volume of a hemisphere (V = circumfence3/118.4) Oprah would have a cranial capacity of 2229 cm3 but this formula overestimates the brain size of black women because they tend to have relatively long heads and thick hair.  For example young black American women in the 1980s had larger head circumferences than White or Asian women, but smaller cranial capacity (though cranial capacity was estimated from an extremely old regression equation that assumed a linear relationship between head dimensions and volume when the true relationship is cubic)

headcircumference

To allow for cubic effects, a better way  might be to use the hemisphere formula and then adjust for the degree of over or underestimation in a particular demographic group.

For example, if their heads were perfectly spherical and there was no inflation for hair, skull thickness or fat and skin around the skull, black women would average a 1398 cmcranial capacity based on their 54.9 cm circumference, but in reality, as of the 1980s they had a mean age 25 brain weight of 1291 g.

brainweight1980

 

If the samples in the army data and autopsy study are comparable, this implies their brain weights are 0.923 as large in grams as the hemisphere formula puts them in cubic centimeters (for simplicity I’m ignoring any putative post-mortem weight gain).  Thus multiplying Oprah’s hemisphere formula head size of  2229 cm3 by 0.923 gives an estimated age 25 brain weight of 2057 g, which is at least 6.4 standard deviations above the mean for U.S. black women and at least  5.7 standard deviations above the mean of U.S. white women.  Given the much smaller population size of well nourished peak age women of all races when Oprah was 25, this would have mad her arguably the World’s biggest brained woman at least until some younger woman from the better nourished generations that followed took her place.  Decades later she would be the World’s most influential woman.

pizza

As mainstream media loses power, Oprah’s high forehead allows her to creatively adapt by entering the frozen pizza business

 

 

Oprah’s head size is the gift that keeps on giving

colin4

Commenter pumpkinhead  describes the above photo:

That is Jarron Collins, NBA player almost 7 foot(close to Shaq’s height albeit in a more slender frame probably smaller head). Note that Oprah’s and Jarron’s heads are on roughly the same plane equidistant from the camera, which makes this a good photo for comparison. Compare head width, he has over an inch on her and I would be willing to wager that his brain is at least a couple of SD bigger than hers and I doubt he even gets close to the 2000 cc mark. Now Imagine his head on Oprah’s body, would that not be freakishly big? That is how big her head would have to look on her body for her to have a brain close to being as big as you suggest. Trust me 1740 cc is generous and after all, astonishingly big(bigger than 99.9% of white men).

Jarron’s head only looks wider because he’s standing on an angle, allowing us to see both the side and front of his head.  Oprah is looking at the camera straight on.

But as a seven footer, Jarron is probably more extreme in head height than head breadth and yet when I put my ruler against the computer screen to measure the distance from their eye brow to their hair line, they both clock in at just under 1.5 cm.

 

 

So not only does Oprah have a cranium height that is comparable to a seven foot black man, but her cranium length may exceeds an average black man’s by 30% and that percentage multiplies when you consider that cranial capacity is a cubic variable.

Having said that, I’m sure there are some black men out there with bigger brains than Oprah, but back in the 1970s, when Oprah reached peak brain age and the well nourished population of the World was much smaller, there were far fewer and whatever few existed likely had much more muscle mass and height than she had at the time.  In the early 1970s Oprah only weighed about 135 lbs,  suggesting a fat-free body weight of only 95 lbs!

missblack

Arthur Jensen notes on page 439 of The g Factor:

Also, we must take into account the fact that, on average, about 30 percent of total adult female body weight is fat, as compared to 15 percent for males.  Because body fat is much less innervated than muscle tissue, brain size is more highly correlated with fat-free body weight than total body weight.  Statistically controlling for fat-free body weight (instead of total body weight) has been found to reduce the sex differences in head circumference by about 77 percent, or about three times as much as controlling for total body weight.

Adjusted for her 95 lb fat-free body size, Oprah was perhaps the biggest brained black on Earth (male or female) at least briefly during the 1970s.  Several decades later she would become the World’s ONLY black billionaire (male or female) for several years.

marry.PNG

Oprah rests her large cranial capacity on the shoulder of idol Marry Tyler Moore

 

 

More evidence for increasing brain size over the 20th century

I compared data from an old and new study of brain size.  The old data was analyzed by FW and EM Appel who wrote in 1942:

The material came from the St. Elizabeth’s Hospital of Washington, D. C. Dr. Walter Freeman, who was formerly pathologist at this hospital, brought certain biometrie data from the autopsy records of the Hospital to the Department of Biology of the Johns Hopkins School of Hygiene and Public Health for statistical analysis. Beginning with
the first autopsy after the founding of the Hospital, the records date from 1884. The records available for the present work run consecutively through 1924, and then skip to a few for 1933. The cases for the interval between 1924 and 1933 were used by Freeman in his studies on the endocrine organs (Freeman, 1931, 1934; Pearl, Gooch, and Freeman, 1935 )•  For the remaining body of material, totaling nearly 4500 data sheets, 2752 records have been segregated. These include all of the male, white cases for which the weight of the brain is given. This array of cases is much more extensive than any series for one sex and one race which has been available heretofore from a single source.

brainbyage

From “INTRACRANIAL VARIATION IN THE WEIGHT OF THE HUMAN BRAIN”
Author(s): F. W. APPEL and E. M. APPEL
Source: Human Biology, Vol. 14, No. 1 (FEBRUARY, 1942), pp. 48-68

This was then compared with more recent U.S. data from a 1980 study from Ho et al.

brainweight1980

From “The g Factor”, 1998, by Arthur Jensen, page 439

The mean age for both the whites and blacks in Ho’s study was about 60 so it’s possible to compare the average  of Ho’s circa 1980 white males with the 55 to 64 year-old white males from 1884 to 1933.  And because Ho et al, used regression to estimate brain size at age 25, we can also compare circa 1980 white men age 25 to the  25-29 year-old while men from 1884 to 1933.

Here are the comparisons:

brainweightpart3

 

Of course it’s possible the brains were not weighed using the same procedure causing such a large increase to be spurious.  However Richard Lynn has been arguing for decades that thanks to 20th century nutrition and health, a major brain size increase has occurred, and is consistent with major intelligence increase.  This makes sense because the last few hundred years have been a quantum leap forward in human achievement.  It took 70,000 years for our population to increase to 1 billion people, yet technology has allowed us to reach 7 billion in just the last few centuries,  not to mention space travel, the internet, and genetic engineering.

Do our brains get heavier when we die?

Commenter pumpkinhead is the second person to doubt my claim that brain weight increases by 9% after death so I thought it would be useful to devote a whole article to this.  The skepticism is understandable since there’s no obvious mechanism by which this should happen.  If I were a theist I might say that when we die we join the spirit world and become omniscient like God and it requires extra brain weight to have all this knowledge.

I first learned about the post-mortem increase by reading J.P. Rushton who cited pg 299 of a 1983 article by Jorgen Voigt  and Henning Pakkenberg  who write:

Appel and Appel [1942a, b] seem to be the first to point out that the brain weight increases post-mortem, mostly during the first 12 h after death, then more slowly,
totalling an average of about 9%. However, experiments with rats [Boyd and Knight,
1963] later showed that the brain weight in these animals does not change very much post-mortem, and the tendency here is to a loss of weight which, in a single experimental group reached a total of 12%. If the results of Appel and Appel [1942a, b] are accepted our brain-weight results should be approximately 9% above the weight in vivo,  as the autopsies are always carried out considerably later than 12 h after death

In the original 1942 article by FW and EM Appel they discuss their equation for predicting brain weight as a function of time since death:

Brain weight (in grams) = 1242.44 + .33 H + 39.72 log H
Here H is the number of hours post mortem.
The curve is certainly suggestive. It suggests that the weight of the brain increases almost continuously after death, at a rate that gradually diminishes. The increase must be limited, but its limit must be beyond the reach of our data. The weight certainly increases for many hours, and possibly it does so for more than 6 days. In the first 12 hours after death the mean weight increases about 47 grams, or nearly 4 percent.
By the end of the second 12-hour period the increase amounts to 63 grams, or more than 5 percent ; by 36 hours it amounts to 74 grams, or nearly 6 percent. If this increase continued for 170 hours after death it would amount to 145 grams, or the amount of the mean loss in weight between ages 25 and 96.
Conjectures as to the implications of this increase are not in order until it has been demonstrated beyond any doubt that the increase is a real phenomenon. Other workers have demonstrated that the weight of the brain varies with the skull dimensions and with the age at death, so there has been no reason to doubt our findings on these points. But no evidence of a post-mortem increase has ever before been presented. It is conceivable that the apparent increase might be due to a chance drift in the age at death, or in the dimensions of the skull, though it is difficult to see why the apparent increase should be essentially continuous and at a gradually diminishing rate if any accident of sampling or distribution is responsible for it. Still, the possibility needs to be investigated

 

Here’s their data for the brain weight increase, so judge for yourselves how convincing it is.

brainweight