He said they broadly reviewed behavioral genetics research and did not mention GCA in this sentence, probably on purpose?
I don't think there is any proof that eugenic policies will fail to work for GCA or even other behavioral traits that are highly heritable. See, e.g., https://infotomb.com/0q783.pdf
Eugenics is just another name for selective breeding and it is hard to come up with a proof that selective breeding works for all other species, but not humans.
> ...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.
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.
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.
>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.
I don't buy that argument. There's no reason to think that evolution has been selecting for cognitive ability as strongly as it possibly could.
It's simple to say "let's have a fatter cow". It is not simple to say "let's have a more intelligent human" because "intelligent" is not a fixed or agreed term.
100 years ago people would have thought mental arithmetic, memorization and rhetorical speech were core parts or indicators of intelligence. I think that most people today would see creative problem solving, social empathy and long term planning as more indicative. In fact the 19th century indicators are now seen (in popular culture) as part of a disorder (autistic spectrum) that is often used to explain the behaviour of otherwise incapable people.
Our culture, communities and technology define our humanity, creating a greater humanity through breeding misses the point somewhat.
Or rather, Pokemon breeding has slowed its roll at zoological notes (rather than incubation for reproductive adjuncts and agonists,) ashram automation hasn't encapsulated all that much microbiology and safety vetting at once, motivators for diversity are copacetic, emphasis on surviving (humanity) long enough to learn and use something is well-vetted, not everyone has replaced themselves with a short dna/rna script, and that the script for talking with your S.O.'s parents just doesn't always veer toward on-point superinfection and reproductive health in the window allotted.
A baby monitor with progress notes on various pivot options sounds great. (Revolutionary Girl Utena model Serta...) It beeps if all the child's career options are deprecated by the next 15 years, and points to an appropriate hill near which those careers fester; or if their social health role is to force vulnerable mutations in (otherwise) epidemic disease (I'm only a Doctor ironically, etc.)
Intelligence might not be a fixed or agreed term, but GCA is fixed and agreed. If you can measure a genetic trait, and the trait varies in the population, then you can bring about population level changes in this trait via selective breeding.
Of course this does not mean eugenics is a desirable activity that we should be engaged in, but I have not seen any rational argument that it has been “proved" to be impossible.
I think GCA originated in 1954; I don't know how many generations of people breeding it would take to get a selected trait - humans are genetically very similar compared to other species; there is not much variation... so I don't have any idea of what the breeding program length would be, but I assume that it would be several generations... so I don't think that an idea that has been around for 60 years would really qualify as fixed and agreed in that time scale.
Also I don't think it's agreed.
Also it's not clear that your statement that population level changes can be created by selective breeding is true - if a characteristic is dictated by alleles that damage fertility or other fitness indicators then it may well not be continuous. In the case of human intelligence the increased child birth mortality associated with large heads and the increase dependence of infants on parents are examples. There may be others which are more relevant to modern life, like propensity to depression, disinterest in sex etc (note : I am using these as examples, not saying that this is so).