Human intelligence quite obviously has some genetic component. Genes do constrain our fate, as does luck, even if development matters more. The way that our capacities develop is profoundly influenced by the environment and by the social situation in which a child grows up. Genetic influence is not genetic determinism and the interplay between genes and development is enormously complicated. A study based on the population of Iceland at first sight makes claims to show that some genes for intelligence are being pushed out of the population. On closer inspection it shows just how tangled these questions are. Researchers have identified a large number of gene variants – the evolutionary mutations associated with traits – which, taken together, correlate with educational attainment (with the caveat that some variants might simply improve self-control and foresight). The work shows these same variants are also associated with having fewer children.
Since evolution can be defined as a change in how common these variants are found in populations over time, this looks superficially as if we are evolving to be less clever. Nature however is swamped by nurture: environmental pressures are working much more strongly in the other direction. There is in IQ testing a phenomenon called the Flynn effect, in which successive generations in every population tested have shown significantly higher IQ scores than their parents. In Iceland, the Flynn effect raises IQ points by about 10 points every generation, while the genetic process identified by the latest research is 30 times as weak. If we extrapolate the Flynn effect backwards in time, so that IQ diminishes in the past at the same rate as it has been increasing in our time, it appears that the Victorians would have trouble reading and writing while Elizabethans would scarcely have been able to produce articulate speech. So much for Shakespeare. On the other hand, the genetic curve, traced back the same way, would suggest that the Elizabethans were all towering geniuses among whom Shakespeare would have been completely unremarkable. Clearly we are not measuring fixed and long-term versions of intelligence in either case.
[Source:-The Guardian]
