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Comment by Daniel_Newby | Hacker News Reader

The divide isn't between SV and the unemployed, but between the educated and uneducated.

And educational status is strongly predicted by IQ in the U.S. EDIT: And since IQ is strongly influenced by genetics, this latest data suggests the U.S. is creating a genetic underclass. Taken far enough, this is the death of the republic.

Under IQ 90, 40% drop out of high school. Above IQ 110, less than 1% drop out of high school.

  Percent with bachelor's 
  degree by IQ (ignoring
  family wealth)

  IQ     %
  ---    --
  85     2
  100    10
  115    30
  130    75

Family wealth has a modest effect. For IQ 100, coming from a super-wealthy family boosts bachelor's degree attainment to 30%.

Source: NLSY project, early 1980s, as analyzed in The Bell Curve in the mid 1990s.

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The NLSY doesn't include a test of IQ. It includes an AFQT test. That stands for Armed Forces Qualification Test. The NLSY tracks young people who are between 14-22 in 1979 through time. Therefore, they take the AFQT test when they are at least 14 and often older. The AFQT test isn't designed to measure intelligence per se. Your argument is pretty much that students who score well on standardized tests in high school and college are much more likely to graduate (or to have graduated) from high school. There are all sorts of correlation/causation problems there.

The AFQT test isn't designed to measure intelligence per se.

Yes, but as the source explains, the AFQT has several sub-tests, and most of them are highly correlated to IQ. (A few, like the automotive knowledge test, are uncorrelated with IQ.) They claim that appropriate analysis of results on the sub-tests allows a reasonably accurate measurement of IQ to be made.

EDIT: Re-checking the source, they mention that in 1989 the armed forces rescored the AFQT to make it more g-loaded and repeatable. The first draft of the book used the 1980 scoring, but they redid it all using the 1989 scoring because it was superior.

And the kind of education that offers real financial benefit is often technical or mathematical in nature.

So there is something I wonder about: is there an IQ "floor" below which very few people will be able to benefit from or even complete this sort of education? What percentage of the population falls under this floor? And what will they be doing in the future as both the "service" and manual labor sectors, the traditional absorbers of people with no degrees or impractical "soft" degrees, dwindle in the number of people employed?

We already have examples of this. What happens to people with Down syndrome? Where do chronically brain-damaged folks work? Where can senior citizens who have fallen prey to dementia get jobs?

Indeed. Note that there is a huge chunk of population in the gap between special programs for the severely brain-disabled and those who are just barely low-IQ enough to not finish high school. These people are being squeezed to death between the minimum wage and the export of manual labor to other countries.

And who is doing the political squeezing? A cognitive elite that are being efficiently skimmed off and segregated by IQ in late childhood. This bodes poorly for the stability of the nation.

Of course, this all depends on how much you trust the entire concept of nations... Maybe that era is starting it's final days, and the next force is going to be global companies that hire the elite across the old national boundaries and the the lower classes are stuck for a long time until the world catches up.

I don't trust global corporations much, though. Maybe it's time to get the king to stop favoring the East India Tea Company so much.

One of the local Carl's Jr fast food restaurants has several employees with Down Syndrome. They bring trays to tables and mop the floor. I think it's great that the management gives them the opportunity to do some productive work.

I think that's really really nice of him but it's not economically relevant. If anything it proves the rule.

You're leaping across logical gaps here. IQ can be predicted by a number of factors (parental wealth, IQ, and education are a few), and research on intelligence is fraught with identification problems. It's hard to believe claims of a "genetic underclass."

It's hard to believe claims of a "genetic underclass."

There have been several large studies of identical twins separated at birth. For a given twin, the strongest correlate of IQ is the other twin's IQ. Likewise, the non-identical but biologically-related siblings do have moderately correlated IQs. However, there is barely any correlation between a twin and their adoptive parents or siblings. This suggests that genetics and prenatal environment determine most of IQ.

There is also strong evidence from gene sequencing that genetics directly affects IQ. Genes that affect sphingolipids, chemicals important in the brain, are known to affect IQ. A variation in the SNAP-25 gene has been found to increase intelligence by an average of 3 IQ points.

I believe there are genetic determinants of IQ. But I think IQ measures only one very specific kind of intelligence. Using IQ as a measure for intelligence is like using guitar skills as a measure of musical ability. There are other instruments too.

Identical twins studies are often flawed, because the environment difference between twins is far from random for obvious reasons. For example, in one of the (often used) minesota studies about IQ and twins, the average IQ of the father was 120, whereas the state average was 105 (see http://psycnet.apa.org/journals/bul/125/4/392/).

And while it has become a cliche, it is still true that correlation is not causation: coming up with correlation is easy, but solid scientific works need to prove that the correlation is not spurious. Most studies don't (this is sadly not specific to discussions about IQ, and is a plague of many studies in too many areas - good statistics are hard).

There have been several large studies of identical twins separated at birth.

Yes, and I am closely acquainted, through attending their graduate student "journal club,"

http://www.psych.umn.edu/courses/fall10/psy8935/default.htm

with most of the researchers who have conducted the best of those studies. An earlier reply of mine here on HN

http://news.ycombinator.com/item?id=2696680

corrects (with citations to current research publications) some of the overstatements seen in popular literature about what twin studies show. There is also not any single gene variant that has large effect on IQ, in the view of those researchers about what the most up-to-date gene association studies show.

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