IQ and all that

Mike Berger writes on the evolving science of intelligence


In writing this column I find myself torn by the intrinsic fascination of science on the one hand and the complicated interaction between science and the general political life of society on the other. So I'll have to compromise.

Many of you will know that Darwin agonised over the publication of his evolutionary theories for decades, fearing the reaction from the largely Christian world he inhabited. He rightly foresaw that his ideas would be interpreted as an heretical attack on established Christian doctrine and on the very foundations of an orderly and moral social order.

He was not the first scientific iconoclast to have such justifiable qualms. But for the fearless support he received from Thomas Huxley "Darwin's Bulldog" his ideas may not have spread as rapidly as they did. Nor, perhaps, was Darwin able to fully foresee the misuse of his ideas to support eugenic and racial ideologies which culminated in the Holocaust and set in motion the cultural tsunamis which make much of research dealing, directly or indirectly, with human history and human behaviour a veritable minefield.

Nowhere is this more apparent than in the field of intelligence. Let's stop right here for a moment and ask the question: when and why did intelligence become such a central issue in both science and political infighting? If you had approached a knight in the 14th century, say, and boasted that you were smarter than him, in all likelihood he would have responded by saying "so what?" and giving you a klap on the side of your head with his sword to emphasise the point.

Being bright in the 14th century did not win you fair maidens, honours, land or deference; being fearless, loyal, appropriately aggressive, strong and athletic did. Good looks and good birth also helped. While stupidity did not win you brownie points, high IQ was not at the top of the list. In fact IQ is derived from the German term, intelligenzquotient, only coined by William Stern in 1912. The word genius, which we associate with high IQ plus creativity, goes way back to the Roman term for the 'guiding spirit' of a person, family or even place. It slowly transformed into denoting an unusual receptivity to ideas and beauty combined with exceptional creativity, a combination which is not precisely captured by IQ but was recognised in very special persons throughout the ages.

Unsurprisingly from the 18th to 20th century, dominated by the industrial revolution and the secular enlightenment with its emphasis on reason, science and measurement and the advent of formal schooling, the concept denoted by the word 'intelligence' came under more systematic scrutiny, first by Galton in the 19th century and then many others after him. For further history and an up to date, primer on the topic see Stuart Richie " Intelligence: All That Matters".

The topic is immense, complicated and deserves to be treated with respect. Don't take anyone as truly expert who hasn't spent 10 years in the field, read hundreds of papers and has had at least a few peer-reviewed articles published in reputable journals. Those criteria disqualify me and I do not write as an expert. My intention in any case is not to focus exclusively on IQ but to explore its bio-political and cultural implications.

But, just to get our heads around the issue, we humans are currently marked out from the rest of life by interactions with thousands of our fellows in an extraordinarily complex bio-cultural niche requiring a set of cognitive and emotional skills beyond anything demanded elsewhere in the biological kingdom. Historically, the challenges to our mental abilities (or intelligence) increased substantially with the advent of agriculture, the industrial revolution and, most recently, the digital revolution.

Thus in the last 10 000 years or so our cognitive capacities, which had developed over hundreds of thousands of years, have been stressed to the limit by our own success. Our ability to learn, adapt and cooperate is the secret to our success so far, but the increased cognitive load has meant that it has become a possible limiting step in determining individual, collective and species-wide success. So under these conditions understanding and measuring Intelligence became important.

Galton in the later 19th century attempted to relate skull dimensions to functional abilities like speed of reflexes and grip strength, but without success. Binet and Simon in Paris were tasked with devising means of identifying children with 'learning disabilities' (to use modern terminology) who could benefit from specialised teaching from those who couldn't. But it was Charles Spearman in the early 20th century who demonstrated that ability in a set of apparently unrelated mental tasks were positively correlated with one another. He concluded that this represented a single, underlying, mental facility which he called the g-factor (essentially equivalent to the popular term IQ). The variation in performance remaining between tasks when the g-factor was subtracted represented task-specific abilities or s-factors.

The century which has passed since Spearman's conceptual breakthrough has seen an enormous body of work from psychologists, mathematicians, educators, neuroscientists and sociologists amongst others on the measurement and underlying socio-biology of IQ. The most common picture of intelligence amongst the cognitive scientists actually working in the field, is a g-factor, reflecting some general neurobiological property (or properties), which sits atop a layer of more specific but limited number of intellectual abilities which in turn is layered above a much larger set of task-specific abilities.

So why the 'controversies which surround this topic? Over and above the normal conflicting interpretations of data between scientists, until the field settles down to a relatively stable consensus, the violent controversies arise from the claim that there is an irreducible hereditary element to the g-factor which cannot be eliminated through social reform, better nutrition, education and the like. And, additionally, the further claim that this hereditary (and thus presumed, unalterable) component differs between groups of people, including between socio-economic class, possibly the sexes and so-called 'races'.

We'll look at the repercussions to such data in later columns.

Mike Berger