Wednesday, September 10, 2008

Decoding ASPM: Part III

Since its discovery two years ago, the new ASPM variant has vanished down the memory hole. Why the hasty burial? One reason is linked to current views about the human mind. The dominant view, at least among psychologists, is that cognitive ability varies similarly among people for all aspects of mental performance, so much so that this variability seems to be explained by one factor alone, called general intelligence or g.

Thus, when Philippe Rushton and his associates studied ASPM, they looked to see whether its variants co-varied with indices of general intelligence, either IQ or brain size. When nothing turned up, they concluded that any relationship to mental ability must be a weak one (Rushton et al., 2007).

In an e-mail, Philippe Rushton went on to explain that:


… these [IQ] tests are highly predictive of work performance, which is often evaluated over long time periods and likely gives plenty of room for excellence from the unmeasured qualities you expect are important. For example, Salgado, Anderson, Moscoso, Bertua, and Fruyt (2003) demonstrated the international generalizability of GMA across 10 member countries of the European Community (EC), thus contradicting the view that criterion-related validity is moderated by differences in a nation's culture, religion, language, socioeconomic level, or employment legislation. They found scores predicted job performance ratings 0.62 and training success 0.54.


Yes, these are high correlations, but they still leave a lot of variability unexplained. Moreover, in the case of ASPM, we may be looking at something that improves mental performance on a very specific task—one that most people no longer engage in. How often do people take dictation nowadays?

And there is evidence that g is not everything. As Steve Sailer notes:

g, like any successful reductionist theory, has its limits. Males and females, while similar on mean g (but not on the standard deviation of g: guys predominate among both eggheads and knuckleheads), differ on several specific cognitive talents. Men, Jensen reports in passing, tend to be better at visual-spatial skills (especially at mentally rotating 3-d objects) and at mathematical reasoning. Women are generally superior at short-term memory, perceptual speed, and verbal fluency. Since the male sex is stronger at logically manipulating objects, while the female sex prevails at social awareness, that explains why most nerds are male, while most "berms" (anti-nerds adept at interpersonal skills and fashion) are female. Beyond cognition, there are other profound sex dissimilarities in personality, motivation, and physiology.

Clearly, if the new ASPM variant does have an effect on the brain, it cannot be a general one that influences all brain tissues. This was already being pointed out at the time of its discovery by anthropologist John Hawks:

Nobody currently knows what these alleles may have done. It seems likely that people with the allele have some sort of cognitive advantage, which ultimately translates into a reproductive benefit. This advantage is probably not associated with greater brain sizes, because the average brain size appears not to have changed appreciably during the past 30,000 years.

So what is going on now? Nothing really. An article came out a year ago about a possible relationship between the old ASPM variant and tonal languages like Chinese (Dediu & Ladd, 2007). But this was the sort of blackboard musing that I like to indulge in. Currently, as far as I know, no lab research is being done.

References

Dediu D.L. & Ladd D.R. (2007).
Linguistic tone is related to the population frequency of the adaptive haplogroups of two brain size genes, ASPM and Microcephalin. Proc. Natl. Acad. Sci. U.S.A., 104 (26), 10944–9. doi:10.1073/pnas.0610848104.

Rushton, J.P., Vernon, PA.., Bons, T.A. (2007). No evidence that polymorphisms of brain regulator genes Microcephalin and ASPM are associated with general mental ability, head circumference or altruism. Biology Letters-UK, 3, 157–60.


Salgado, J. F., Anderson, N., Moscoso, S., Bertua, C., & Fruyt, F. D. (2003). International validity generalization of GMA and cognitive abilities: A European community meta-analysis. Personnel Psychology, 56, 573-605.

9 comments:

The Colonizing Ape said...

Great follow up! Now, if I could get a grant for a DNA genetic analyzer, and a few language tests, I would have a great dissertation opportunity.

Marc said...

Kind of anti-climactic. Did you make these points to Rushton? How did he respond?

Peter Frost said...

Colonizing ape,

The best strategy is to 'piggyback' on another research project, preferably one investigating the VWFA. There are many such projects ongoing.

Marc,

Alas, what can I say? Perhaps my posts will re-activate this area of research.

I did make these points to Rushton, but he didn't seem convinced. Keep in mind that the concept of 'g' has been harshly criticized by many people (usually non-psychologists) who are not interested in honest argument.

When a debate degenerates into 'Us' versus 'Them', it's difficult to get constructive dialogue.

Tod said...

East Asian populations have a relatively low level of ASPM and seem to have have rather high g (and general work performance). It is hardly surprising that ASPM couldn't predict those things in individuals by the same tests.

If ASPM is really so specific to the work of scribes then it may have ceased to provide any status/reproductive advantages a very long time ago. Is it possible to determine if it continued to be selected for to any extent after the scribe era had passed?

Peter Frost said...

Tod,

I wouldn't say "a very long time ago." The first printing press was invented in the 15th century. Even 150 years ago, people wrote down the minutes of meetings in longhand.

I remember how arduous writing was before I began using a computer (mid-1980s). I would write up my assignments in longhand and then type them on a typewriter. If I wanted to add any material, I would literally have to 'cut and paste'.

Tod said...

"Matched groups of American and Chinese children were asked to recite the counting sequence from the number one. At age four the American children could count up to 15 on average whereas Chinese children could count up to 40.

Miller,K.,Smith,C.,Zhu,J.,& Zhang,H.(1995) preschool origins of cross-national differences in mathematical competence:the role of number-naming systems.
Psychological Science 6,56-60.

One reason for the relatively poor performance of the American children seems to be that two digit
numbers are less transparently represented in English than in Chinese... Natural languages show the traces of various attempts at finding a proper representation of numbers...there are special words for the numbers 1 to 12 that are vestages of an earlier base-12 system... (which was) also used for money and length. Special words for the numbers between 13 and 20, such as 'thirteen' and 'fourteen' harken back to an earlier base-20 system. Chinese, in contrast, denotes numbers consistently in the base-10 system". Quoted from G. Gigerenzer, Calculated Risk (2002)

Some of the early scribes most important duties, to calculate how much a lord was owed, might have involved using base-12 or base 20 systems of money or weights and measures and calculating with an unsatisfactory base-10. "Roman numerals are base-10 but do not facilitate multiplication or division" of course so these early scribes may have been coping with work an order of magnitude more demanding than such calculations would be today.

Tod said...

A bit off topic; the Dedui linguistic tone paper's reference 33 which concerns the heritabilty of musical pitch processing and linguistic tone, the following paper may have a bearing on this and also your delayed maturation hypothesis http://calibrer.ucpress.net/doi/abs/10.1525/mp.2001.18.4.491

Absolute Pitch in Williams Syndrome is is the title in case the link doesn't work

Johnathan said...

So, I do not really imagine this is likely to have success.
here

Constantine said...

It cannot really have success, I suppose so.
bas-saint-laurent