Studies of intelligence quotient (IQ) differences in a population seem to entail that the variance of intelligence between individuals is predominantly the effect of genetic difference. In fact, genetic variance is said to account for almost 80 per cent of the IQ variances in the population, leaving just 20 per cent of the variance to be attributed to environmental differences. The role of the family, social and cultural environment, according to these data, contribute little to the mould of a person’s intellectual character. The variance of the predetermined hardware, and not the accumulated software, seems to make the difference in one’s cognitive acumen.
These heritability estimates are formulated using monozygotic and dizygotic twin studies. The experimental paradigm operates by giving identical twins, reared in separate environments, IQ tests. Since the twins’ genotypes are identical, any difference in IQ scores should be from any influence in their separate environmental surroundings. Similarly, the IQ differences between dizygotic twins (different genotypes), who’re raised in the same environment, would be attributed to the difference in their genotypes – as that is the only dissimilar variable. Taken together, a yielded estimate of how much genes, and conversely environment, account for the variance of IQ scores can be given.
James Flynn of the University of Otago, however, documented a phenomenon constituting large IQ differences between proceeding generations. These IQ differences between the generations were not meagre, for instance, the Dutch – from 1952 to 1982 – gained 20 IQ points. Israeli IQ gains were similar in magnitude. If IQ variance is, in the main, dictated by genetic variance then why have such large gains appeared between the generations?
Gene variance is an inadequate explanation for the rise of IQ’s from generation to generation. We can be sure of this as Flynn compared the scores of a Dutch 1982 cohort (randomly selected) with the scores of their corresponding fathers. This result, therefore, allows us to control for differential reproductive patterns that could have provided genetic diversity to the testing sample. Another genetic possibility, known as ‘hybrid vigour’ – a method of genetic recombination, mechanised through the entanglement of two divergent genetic profiles (e.g. mother and father), which allows the dominant and survival inducing genes to be expressed over any recessive counterparts – is also hypothesised. This effect may have contributed to gains made during the first half of the century, yet, the effects of genetic diversity and hybrid vigour would’ve tapered-out. Certainly, hybrid vigour would’ve accounted for little of the variance in IQ gains for those born in 1954 and 1956, cohorts who demonstrate an 8-point IQ gain over 10 years. Thus, the only game in town that would explain these phenomenal IQ gains is, in fact, a change in the environment. So, why do heritability estimates assign little effect to the environment in determining IQ?
Flynn argues that the comparable weakness of environmental facets affecting IQ is a result of an implicit assumption in heritability estimates, which infers that environment and genes are independent of one another; that is, genes do not co-opt the surrounding environment, nor does the environment affect genes. “Applied to basketball, this implies that good coaching, practicing, preoccupation with basketball, and all other environmental factors that influence performance must be unrelated to whether genes contribute to someone being tall, slim, and well coordinated,” Flynn and Dickens, of Brookings Institute, contend.
In order to crystallise Flynn and Dickens’ critique, take my personal aptitude for playing tennis. Presumably, my particular genetic profile – entailing genes that may bias my phenotype in the direction of a slight advantage in hand-eye coordination – would correlate to the genotype of my (hypothetical) daughter. Because of a genetic predisposition and my enthusiasm for tennis, me and my daughter would be more likely to engage in tennis practise at an earlier age. My daughter, thus, would conceivably be slightly better than others of her age and would be more likely to get picked for school teams. This would give her a greater sense of gratification and achievement which, then, implores her to take on more practise. The additional practise, again, would improve her skill set and enjoyment of tennis even further. She would now be a prime candidate to receive expert coaching and an abundance of opportunity. My hypothetical daughter has now attained a set of skills that will likely enable her success in tennis – more success than would be likely if her only distinction was the aforementioned genetic predisposition that expressed above average hand-eye coordination. Flynn and Dickens coined the term ‘multiplier effect’ to describe the accumulative effects a small initial advantage can have, given it is matched with a corresponding and enriching environment.
If, now, we take another hypothetical, with this time my daughter having a monozygotic and adopted twin; the adopted twin would have the same genetic hand-eye coordination advantage, meaning, she would likely be slightly better at tennis, given the opportunity. After playing tennis for the first time, a multiplier would occur, leading the adopted twin to also be good at tennis. It was the environment, therefore, that introduced them both to tennis, genes that allowed them to enjoy it slightly more and, then, environment again that multiplied both those factors allowing the potential to flourish. In a heritability estimate, however, these environmentally induced multiplier effects would not be taken into consideration, resulting in all the effects being attributed to a genetic predisposition.
This analogy illustrates the intrinsic association between one’s genetic predispositions and one’s environment. And, therefore, as Flynn and Dickens opine “the match between genes and environment means that environmental factors, however potent, to a large extent just reinforce the advantage or disadvantage that genes confer. So the match masks the potency of environmental factors.”
The modernity industrialisation has induced upon our societies is likely to have implored the demand for cognitive complexity within the workplace. Academic credentials, now, have become a necessity for entry into the job market, and there is far more saturation in scientific, managerial and technical positions. Additionally, Flynn provides evidence in his book ‘What is Intelligence: beyond the Flynn effect’ for the willingness of individuals, post 1940, to apply more consideration to abstract propositions, rather than adhering strictly to the concrete. These incremental changes undertaken by most societies perhaps has, in accumulation, left its footprint upon us through its effects of raising the average IQ.
This increase in average IQ matters, as when children have over the years defied expected boundaries on academic tests and have done much better than their precursor generation, the explanation of such an occurrence often entails the following utterance “the tests must’ve gotten easier and the curriculum watered-down.” This argument has infected educational politics, for instance, in the UK Ofqual – an exam regulator– and Michael Gove (once the Education Secretary), have noted a desire to change the grading system to intentionally make it harder for students to obtain the highest grades. IQ gains, to the tune of 20 points, would imply that an improvement in academic scores – if IQ in fact does predict academic success, which it does quite well – should correlate to such IQ betterments. In fact, these academic gains were completely predictable and expected had one paid attention to Flynn’s findings. This trend is, also, illustrated in the rise of individuals opting to go into higher education around the world: a rise of 20 per cent from 1971 to 2013.
So, on the contrary to tests getting easier, students are perhaps just slightly smarter due to being subjected to a better and more cognitively complex environment. Thus, instead of constantly claiming that it cannot be a fact that children are privileged to a greater intelligence, maybe we should reflect on the societal progress that has made IQ gains even possible. We should celebrate and seek to understand progress, not treat it with suspicion.