The rise and fall of intelligence

From an unlikely source comes anecdotal evidence of rising intelligence. In this week’s Spectator (registration required, so no link) Matthew Parris quotes his (conservative) old man; “Young people are more intelligent these days.”

This is, of course, just what IQ tests show. It’s the Flynn effect. Jim Flynn has estimated that only 10 per cent of Britons born in 1877 had an IQ of 75 or more, whereas 95 per cent of those born in 1967 had such an IQ (“IQ Trends Over Time” in Meritocracy and Economic Inequality, edited by Ken Arrow and others).

Lest we think such enormous gains are implausible, remember how stupid people were in the 19^th century. In The Condition of the Working Class in England, written in 1844, Friedrich Engels quotes an official survey of young people in Birmingham:

A boy, 17 years old, did not know that twice two are four, nor how many farthings in two pence even when the money was placed in his hand. Several boys had never heard of London or Willenhall, though the latter was but an hour’s walk from their homes…Several had never heard the name of the Queen nor other names such as Nelson, Wellington, Bonaparte.

One reason why intelligence has risen from such levels is probably that later industrialization has increased the amount of stimuli people get, thus giving them knowledge by osmosis and forcing them to be more intelligent to cope with increasing complexity.

This, though, raises the question. If intelligence has increased massively since the 19^th century, why have the peaks of human achievement declined since then? Our politicians don’t compare to Gladstone, not our novelists to Dickens, still less our public intellectuals to John Stuart Mill. Here’s four reasons why this might be:

• There’s no increasing stratification of IQ. Flynn estimates that the IQ gap between upper and lower classes has been stable over time. Regression to the mean, it seems, exactly offsets the effect of assertive mating. This means the number of extremely high IQs doesn’t increase, except insofar as mean IQ rises.
• Intelligence is only a small part of what is required for success. Hard work and wisdom don’t necessarily increase as IQ increases.
• Politicians, novelists and intellectuals today are not selected for their intelligence. The only talents that matter are a gift for self-promotion, a capacity for tolerating idiots and an ability to articulate the tribal prejudices of some part of the middle class. For evidence of this, just look at the career of (insert name here*).
• The same vast amount of stimuli that increases basic intelligence also stops us working hard enough to cultivate intelligence. By the time I’ve finished blogging, read others’ blogs, read the papers, practiced guitar, listened to some CDs, played Civ III and watched Corrie, I’ll have no time left to do brilliant work. Well that’s my excuse…

* What was the first name you thought of? I’ll bet it was a woman.

Comments

[Tim Worstall]

I'd plump for nutrition as the cause of rising IQ's, myself.
Can't prove it of course but:
1) We know that inadequate nutrition in childhood reduces IQ.
2) We know that nutrition in childhood has got better over the past century and a half (ricketts was not unknown only 50 years ago, for example).

I'm not all that certain that we need any more complicated explanations than that, although willing to be corrected, of course.

[Dave]

Diet was my first thought too, but I'm not happy about the rickets comparison because, like scurvy, it's a disease of deficiency: and once you have enough vitamin C or D, more doesn't benefit you at all. Diet was poor during WWII, yet there was a high demand for Penguin Books (probably higher than there is now), so lot of people were prepared to do some intellectual reading.

Instead, the rising IQ phenomenon reminds me of Stephen Jay Gould's The Mismeasure of Man. IQs were uniformly lower in people from Southern Europe. I suspect were're becoming culturally more homogenous around Northern European values, and IQ scores reflect that. But I don't believe IQ is of much use anyway. Most of its adherents use it as a justification for unpleasant racist claptrap.

[Blimpish]

Cheers for the link - will reciprocate.

IQ's an indicator of cognitive capacity... This explains its continuing interest; but also the interest in manipulating it.

The increase maybe also has something to do with increased information flow, with newspapers, TV, radio, more free time to take it in? Admittedly, this has been at the expense of depth (entertainment wins over education), but doesn't most research suggest that cognitive ability is pretty much determined in the early years of childhood... where depth is less important than scale of exposure, I'd guess?