I have to politely disagree with your conclusion. If I may, I would like to expound upon my opinion.
Based on the information available and at least on an individual scale, the average human is roughly as smart or smarter than our ancient ancestors were. Of course, no reliable testing data exists further back than a generation or two, so any commentary on human intelligence positive or negative is somewhat subjective.
However, I think it is fair to say that the issues we are having today with the seeming increase in the number of "stupid" people is not so much an indicator of declining human intelligence, but an artifact of our modern society.
Simply put, the pace of technological and social changes in society is occurring at a faster rate than the average human can keep up with. While we can keep up with the changes in a specific discipline, (say, automobile tech or computers or the like) it is nearly impossible for our brains to process all the changes that are happening at once. We simply can't keep up.
Combine that with a massive increase in the available information (thanks to the Internet) and our ability to make rational risk-assessments becomes more and more compromised.
Now compound that with the fact that western culture, capitalism and medicine have greatly reduced the average western mortality rates, thus allowing our population to increase and the average number of less intelligent and otherwise mentally challenged people to survive and you will have a spike in "stupid behavior".
Really, there are only two ways to deal with this:
1. Government regulated breeding. Only works as well as the regulators running it, and based on the current crop of regulators, I'd not want to bet my society (or my kids) on it. Not to mention the hideous tragedies such tyrannical policies would create.
2. Increased educational focus on logic and reasoning and a "classical" education approach. IE: Logic & Reasoning, Math, Science, History and Arts & Technology as focuses in primary and secondary education.
I personally think that option 2 would be far more effective in the long run than option 1. Far better to equip all of our children of all intelligence levels to be able to handle modern society via clear reasoning and improved risk assessment skills than to attempt the impossible task of breeding perfect people.