Interesting article here on recent human evolution. Apparently brain size in humans has shrunk in the last 5000 years. A possible reason is given in the article I will link to:
Humans Still Evolving as Our Brains Shrink - Evolution | Human | Theory | Man | Paleontology - FOXNews.com"When it comes to recent evolutionary changes, we currently maybe have the least specific details with regard the brain, but we do know from archaeological data that pretty much everywhere we can measure — Europe, China, South Africa, Australia — that brains have shrunk about 150 cubic centimeters, off a mean of about 1,350. That's roughly 10 percent," Hawks said.
"As to why is it shrinking, perhaps in big societies, as opposed to hunter-gatherer lifestyles, we can rely on other people for more things, can specialize our behavior to a greater extent, and maybe not need our brains as much," he added.
In other words, the need to be intelligent isn't as much of a biological imperative as society becomes more complex. Stupid people are able to survive and reproduce. The phenomenon that we see today, with the less intelligent underclass reproducing itself at a higher rate, has been present for some time.
Please vote on your opinion of this theory.