The question of plasticity of the brain is the real key to the whole debate.
In addition there are many latent potentials distributed across populations, never measured in any test. In addition there seems to be question of ‘take off’, Jews were once thought unintelligent, and the last generation shows the beginning of sudden take off in black populations suddenly showing remarkable musical potentials (and much else). There is a tortoise and the hare factor here: and the real measure takes many centuries.
The complacency of many is considerable: in fact the level of intelligence in modern civilization is clearly marginal: ways need to be found to expand both intelligence and ‘consciousness’, that favorite of new agers. One can have expanded consciousness but lesser intelligence ( a factor exploited by some yogis who wish to shut down the mind to discover latent consciousness, don’t try that at home, go find a zen monastery).And this impinges on ethical and aesthetic unknowns. Ethical reasoning would seem to be degenerating in the political field of so many psychopathic politicians: what is the status of machiavellian politics: smart or stupid?
Psychologists often use puzzles to test intelligence. So, puzzle this: on the one hand, many psychologists tell us that intelligence is an enduring individual trait, pretty much hard-wired by a person’s DNA and by cell development in the fetus’s brain. On the other hand, testing shows that there have been huge increases around the world in IQ scores over the last two or three generations—so large that most Western adults a century ago would be considered dimwits by today’s standards.
Source: Getting Smarter | Boston Review