23 December 2009

Four Genes Controlling Size of Brain, IQ

Brain size is highly correlated to IQ, and brain size is largely under genetic control. Researchers at the University of Oslo, UCSD, and Scripps Translational Science Institute have published a study in PNAS (21 Dec 2009) showing that common gene variants associated with microcephaly can explain differences in brain size [and IQ _ AF] of healthy individuals.
The microcephaly genes have been hot candidates for a role in the evolutionary expansion of the human brain because mutations in these genes can reduce brain size by about two-thirds, to a size roughly comparable to our early hominid ancestors. There is also evidence that four of the genes -- MCPH1, ASPM, CDK5RAP2 and CENPJ -- have evolved rapidly and have been subject to strong selective pressure in recent human evolution.

"It is obvious that such anatomical changes must have a basis in genetic alterations, said Lars M. Rimol, a research fellow at the University of Oslo. "Until now, little has been known about the molecular processes involved in this evolution and their genetic underpinnings. Now we have a piece of that genetic puzzle." _ScienceDaily

It is becoming clearer that the evolution of humans has continued over the past 10,000 years, and perhaps accelerated over the past 4,000 years with civilisation.

Significant differences in group IQ means between racial categories correlates well with differences in achievement, as measured in a wide range of fields.  (see Human Accomplishment)

Much of the dispute regarding the findings of population IQ differences derives from the blatant political bias of egalitarians of a leftist and / or Marxist variety.   The late Stephen J. Gould, Dick Lewontin, and others -- see references here -- have attempted to dispute, bully, block, intimidate, and otherwise diminish the results of scientific research relating to IQ, with little success in scientific circles.  The mainstream media and mainstream social science and humanities academia hue to leftist political correctness and self-blinding.

But as genetics and genetic anthropology continue to build a solid scientific foundation beneath obvious population macro-differences in aptitude and achievement, room for dispute will shrink accordingly.

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Blogger Sojka's Call said...

The data presented on correlation of brain size to IQ and the genetics controlling brain size is very solid and presents a convincing case.

The Human Accomplishment, info is less convincing because the author minimizes Asian accomplishments. Asians have the highest IQ according to some other data and hence should have the most accomplishments so either the hypothesis of IQ to accomplishment is false (I don't think so) or Asian accomplishments have not been given their due in his study.

The other statement I am having trouble following is the one saying the people disputing racial IQ differences are all egalitarian leftists or Marxists. Maoists had an inferiority complex in the beginning of the current (Red) China from their long domination by the Japanese and British. And, I don't think leftists have a monopoly on disputing science. The fundamentalists do a fine job of that themselves.

To sum up, I think you wrote a good blog whose message is somewhat muted by blaming leftists for bottling up or minimizing these findings and then lumping the leftists with Marxists. That just gives someone with a left leaning political bias an easy out to not seriously consider what you are saying.

Wednesday, 23 December, 2009  
Blogger al fin said...

Fair enough. Perhaps it is just that I do skim the leftist blogs that deal with IQ, and see the denial on a daily basis there. I tend not to see the same levels of science denial at other sites I scan.

I purposely put a slash "and/or" between leftist and Marxist and to show that they could be distinct from each other -- but not necessarily.

I went through my own leftist phase in college, but it didn't take me long to understand the essential contradictions and dead-endedness of leftist theory and policy.

Wednesday, 23 December, 2009  
Blogger Unknown said...

Why are parrots so relatively smart? Because neuron density is a factor.

Also, check out a one-gene effect, found by Plomin, that is essentially a bigger glucose carburetor. Zoomie, eh?

The entire intelligence story is very much mult-factorial.


Wednesday, 23 December, 2009  
Blogger Unknown said...

Does this mean we're all going to end up like the guys on Star Trek with the big heads? (Simple extrapolation.)

Does this mean women actually prefer mating with guys with big heads? (Would seem to be necessary to conserve the trait.)

Are big-hair blondes trying to fool guys into believing they have large brains? (Or are guys focused elsewhere? This one is too hard.)

Just some random thoughts. I have more but don't want to turn on this massive 7 1/4 hat-holder.

Wednesday, 23 December, 2009  
Blogger Aki_Izayoi said...



Derived changes in genes associated with primary microcephaly (MCPH) have been suggested to be “currently sweeping to fixation” i.e., increasing in frequency in most populations, with the likely outcome that the derived allele will completely displace the ancestral allele over time. Possible causes for this sweep include effects on human reasoning and language. Here we test the hypothesis that these derived alleles are associated with current variation in spoken or written language and related traits. The association of derived alleles of the ASPM, MCPH1, CDK5RAP2 and BRCA1 genes was tested against well-validated measures of dyslexia, specific language impairment, working memory, IQ, and head-size in a family-based association study of over 1776 subjects from 789 families of twins. No evidence for association was found for any gene to any trait. The results strongly did not support the hypothesis that derived alleles in MCPH-related genes are related to the evolution of human language or cognition. Results were compatible with the alternate hypothesis, suggesting that adaptations in these genes associated with a dramatic increase in brain size have long since reached fixation and are now maintained by stabilizing selection."

Basically, three out of the four genes listed in your blog posts (and one associated with Cochrane's Jewish hypothesis) were not associated with variance in IQ.

If you are still reading, what is your hypothesis for the origin of racial differences in intelligence? Richard Lynn argues that cold whether provided a selection pressure that resulted in Orientals and Caucasians having higher intelligence. In addition, Lynn also argues in Race Differences in Intelligence that Inuits have an IQ between other native americans and Caucasians as their cold environment selected for intelligence, but they were not exposed to mutations that enhanced IQ in the other Asian and Caucasian cohorts.

Friday, 01 January, 2010  
Blogger al fin said...

Aki, Al Fin geneticists are not committed to any particular "IQ genes". When different scientists reach different conclusions using the same data, it is too early to close the books and declare "the debate is over." This debate has just started, and relies upon a continuing flow of data. In other words, IQ is determined by genes, partially. Which genes? How do they work? These and other questions require sorting out. It may take decades longer.

As for why different populations adapted differently to environmental challenges -- some developing higher IQ, and some developing resistance to malaria etc. -- that is a fascinating question.

You may want to compare the contemporary Japanese population with the Ainu. Or compare the different populations of the Indian subcontinent which have a wide variation of mean IQs.

It would be fascinating to find a subsaharan African tribe with an average IQ of 100 or higher. That would stir the pot a bit!

Saturday, 02 January, 2010  
Blogger Unknown said...

First, please DISTINGUISH between E Asian and S Asian and W Asian; and N European, W European, E European, and S European.

Because the accomplishments of East Asians (Chinese, Japanese, Korean) are much more than SE and West Asians (Vietnamese, Cambodians, Filipinos) as of now.

Because the accomplishments of Northern and West Europeans (English, Germans, French) are much more than East + Southern Europeans (Spain, Portugal, etc) as of now.

Chinese inventions/accomplishments (or at least first found in China): gun powder, paper, cast iron, toilet paper, paper money, (evidence suggests) cannon and guns, compass, printing and other cool stuff ( ALL BEFORE 1600 century ).

English/Germanic inventions/accomplishments ( includes American because Americans are considered Anglo-Germanic) : Calculus, evolution, electricity, motor, atomic bomb!!!, first to the moon!!!!! and a whole lot of amazing amazing stuff. (ALL AFTER 1600 century)

Despite being a prolific reader, I cannot find too many great inventions from Southern and Eastern Europe (This excludes RUSSIA, because Russia is huge), and Southeast Asia.

Note: Western Europeans, Northern Europeans have larger brains than Southern and Eastern European -- according to what I read.

Northern and Eastern Asians have larger brains than Southern Asians and Western Asians -- according to what I read.

Note: The statistics are taken from the same researchers generally. They are not reported by their country of origin, but researchers from, say England, would go to China, Japan, and et cetera to collect these information -- AND THERE HAS BEEN MANY RESEARCH DONE INDEPENDENTLY TO COME UP WITH VERY SIMILAR RESULTS. North + East Asians are statistically shown to have larger brain and higher IQs (just a couple of points more than Europeans) --BUT IQ IS NOT EVERYTHING.

It is generally true that people from the North have larger brains.

And if you haven't notice the Northerner's IQs are higher than southerners IQs for ASIAN OR EUROPEANS.

And if you haven't notice Northerner's N+W Europeans (English, Germans, French) and N+E Asians(Chinese, Japanese, Koreans) contributed more to inventions than say S + E Europeans (Spanish, Portugese, etc) and W + SE Asians(Filipinos, Vietnamese, Cambodians).

Before the Renaissance (about 16th century) East Asia was about as advance as Europe -- actually sometimes the East Asia was more advanced. 16th century and on Europeans exploded in this technological "race" with the their reliance on science and mathematics.


Saturday, 16 June, 2012  

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