| > ...research like that in which contemporary behavioural geneticists engage helped to undermine the eugenics movement by proving that eugenic policies could not achieve their stated goals. What's being discussed here is the historical eugenics movement. Just from the text of the article, it becomes clear that the multi-generational confounding effects like prosperity, education, and social class would make an naive effort pointless. More generally, you should think of the problem thusly, I suggest: Even with extensive genetic surveys, there are no clear candidates for genes that one would wish to select for that present themselves; this is consistent with the notion that general cognitive ability is evolutionarily advantageous. It may be that g.c.a. is locally maximal; that there is no easy conflux of changes which could occur that would predictably raise the g.c.a of human individuals. A hypothetical change might for instance do something that would seem likely to increase cognitive ability, in the abstract, but carry a systemic cost that either prevents such a change from manifesting itself, or renders the value of such a change moot. For most people, I believe, it seems intuitively clear that eugenics is analogous. We know that eugenics efforts cannot produce any remarkable or decisive selection for increased cognitive abilities. We know this because eugenics is a sort of hobby-horse form of evolution, across handfuls of generations, and because evolution cannot, taken over thousands of generations, select any more strongly for increased cognitive abilities than it already has. If it could, it would; thus we must conclude that it can't. We also know that eugenics requires a society that permits centralized, forcible control over how and whether individuals combine genetic material to produce offspring; it requires a society wherein all individuals can be indoctrinated so as to cooperate with this effort; it requires a society wherein these means of force and social control cannot be usurped or arrogated by elements of that society so that they may be directed towards other purposes; and it requires that this state of affairs persist for a modest number of generations, perhaps twenty to fifty. It seems very likely that selection for eugenics is something which will fail because of the systemic costs that it would entail. In fact, it seems more likely than not that eugenics is something that would have arisen in the course of history, already --- perhaps for more trivial purposes than increasing cognitive ability --- were the social structures required not too fragile to sustain the effort. |
If this argument were true then it would not have been possible for the evolution of human intelligence to have occurred.
You have assumed that having a higher gca did not have a cost higher in the past than it does now. The environment we live in today is very different to that of even our recent ancestors.