I once read that some archaeologist had calculated that the average IQ among ancient Greeks of the Golden Age was around 120.
Considering all the brilliant men produced by a city of never more than 100,000, that makes sense to me.
US population in 1770s = 2,500,000. Leaders include Franklin, Jefferson, Madison.
US population in 2010s = 316,000,000. Leaders include Obama, Biden, Kerry.
Proof that natural selection does not favor intelligence?
Well, we’ve been killing off the best and brightest with wars for thousands of years. So, I wouldn’t be surprised if we have lost some IQ points, on average.