One of the quickest paths to career suicide for an academic or any public figure, is to assert that human intelligence is genetically bounded, and roughly 50 - 80% heritable. The preponderance of scientific evidence points toward a genetic limiting of the "g factor" , commonly associated with intelligence, with substantiating research coming from China . And yet the existence of the " Flynn Effect " -- the apparent rise in IQ test scores across several national populations over the past century -- has led many people to suggest that the IQ measure is too changeable to be a true indication of genetically "determined" intelligence.Average IQ scores in many nations have apparently risen by between 5 points and 25 points per generation , over much of the past century. The increase has come largely in the measure of "fluid intelligence," which is one measure of problem-solving capacity.Explanations for this general, but uneven, trend include better nutrition, better education and familiarity with testing, a more stimulating childhood environment, better control of childhood infectious disease, and an increase in hybrid vigour from less inbreeding of populations. Changes in variance for the different sample distributions can also introduce problems in interpreting such a trend.The issues of general human intelligence , and the genetics of intelligence , are complex and multi-factorial. Many genetic and epigenetic factors are involved in the "biological bounding" of human intelligence, as well as other biological and environmental factors which bear on gene expression.It is never a question of "either genetics or environment," but is always both. Thus it is not a question of genetic "determination" of intelligence, but rather a genetic bounding of intelligence. It can be easier to understand that measures such as height potential or "tallness" are "genetically bound" (in the absence of hGH and other exogenously administered growth factors). Similarly, intelligence potential is genetically bound in the absence of NZT or other hypothetical efficacious brain boosters.So are people really getting smarter? The Flynn effect does not seem to be particularly relevant to the high IQ end of the distribution . So the smarter people do not seem to be getting smarter. But part of the lower end of the distribution seems to have moved toward the middle, and parts of the middle may have moved toward the higher end, on IQ test scores."Flynn Effect" improvements in scores seem to have slowed consiberably in advanced nations over the past 20 years. Whatever the cause of the trend, it may have largely played itself out in those nations. But if better nutrition, higher levels of stimulation, and lower infectious disease load are at least partially responsible for the trend of rising IQ scores, we should expect improvements in scores across the more impoverished areas of the third world which are able to move out of poverty.How much of an improvement? One possible answer would be to look at the children of affluent persons in third world nations, as a "preview of coming scores." Rich people's children are generally provided with the best medical care, education, and generally more intellectually stimulating environments. Look at the top end of performance for the most advantaged children in these countries. What do you find?You will find the "gifted" and "advantaged" in countries across Subsaharan Africa topping out at 1 standard deviation below average populations of the advanced world and about 2 standard deviations below gifted children in the advanced world. In most of tribal Asia, gifted and advantaged groups top out at roughly 1 standard deviation below their counterparts in advanced countries -- higher than Africans but significantly lower on average than East Asians and Europeans.Similarly, you can look at the segment of African American children in the US which is most advantaged and gifted, and find persistent IQ score gaps between this group and far less advantaged European and East Asian children -- who nonetheless score higher on IQ and aptitude tests than their more advantaged black cohorts.It is wrong to assume that the Flynn Effect will raise the overall average human IQ score of Earth, and it is wrong to assume that it will equalise IQ scores between population groups which have maintained stable and long-lasting differences in IQ scores over time.Whenever nutrition, education, medical care, and intellectual stimulation are roughly equal, the genetic component in bounding intelligence comes to the forefront. Of course there is always room to improve on all those counts -- and on other determinants of intelligence which have not yet been discovered or delineated. But underneath it all, is the genetic component which will never be equalised, but which may well be compensated for with clever science and technology, in the future.Al Fin cognitive scientists and psychometricians feel that the nutritional and infectious disease components were of limited relevance to the Flynn Effect in the advanced world since the 1940s -- except among truly impoverished populations, which are rare in the western developed world. Other explanations for the increase in scores which are more likely include increased early childhood stimulation and a greater familiarity with test taking.The "critical window of development" theory is likely to be quite pertinent to the Flynn Effect in western populations over the past century. If a child is exposed to language, music, math, executive function training, and certain types of abstract thinking within the critical developmental timeframe, it is more likely that he will emerge from that period with better developed skills.IQ gains in childhood that come from a highly stimulatory intellectual environment may not be permanent, however. And not all children will tolerate such external manipulations well. But the more cognitive and behavioural competencies the child is given at an early age (within reason), the more likely he will be to retain at least some of them. Each child is an individual and should be treated as such.In conclusion, the Flynn Effect is a variable and limited trend in the rise of IQ scores across many nations. It should be yet another reminder of the remarkable complexity of human intelligence and behaviour, all of which derive ultimately from the human genome.

Labels: behavioural genetics, Flynn Effect, IQ