Evolution doesn't say that at all, evolution predicts that the fittest for their environment will survive. Given that the number of children one has is inversely correlated with 'intelligence' it would seem that the stupid are more fit to survive by nature of their willingness to pass on their genes.
Social Darwinism is not the mode of operation for industrialized nations so it's debatable whether there are any significant evolutionary fitness functions in place in the first world.
Like most of science, rhetoricians rely on a poor understanding of what evolution actually says to foster ideas that have no basis in any meaningful scientific understanding of the topic, but seem to make common sense.
The funny thing about evolution and rhetoric is that evolution is usually used to create acceptance for the policies that will make the fitness function a reality. (eg. mutilating the reproductive organs of those who score low on IQ tests)
If you have a citation for professionally published research on the point I would be happy to look it up. More good information about the subject can be found at
"Although much of the research into intelligence and fertility has been restricted to individuals within a single nation (usually the United States), Steven Shatz (2008) extended the research internationally; he finds that "There is a strong tendency for countries with lower national IQ scores to have higher fertility rates and for countries with higher national IQ scores to have lower fertility rates."[23]"
"At present rates of fertility and mortality and in the absence of changes within countries, the average IQ of the young world population would decline by 1.34 points per decade and the average per capita income would decline by 0.79% per year."[25]"
Thanks for the link to Wikipedia, which I help edit, but you have to know that all the Wikipedia articles related to human intelligence are suspect summaries often based on suspect sources, as they have been the focus of a long-standing dispute with much edit-warring
> the average IQ of the young world population would decline
I don't thinnk IQ is the right measure for that... IQ is defined in terms of the average intelligence (really, it's the median, but unless the distribution is strongly skewed, it's almost the same).
Social Darwinism is not the mode of operation for industrialized nations so it's debatable whether there are any significant evolutionary fitness functions in place in the first world.