We know the brain has been evolving in human populations quite recently," said paleoanthropologist John Hawks at the University of Wisconsin at Madison.
Surprisingly, based on skull measurements, the human brain appears to have been shrinking over the last 5,000 or so years.
"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. (source)
It’s usually assumed that humans have steadily increased in intellectual capacity. But what if this trend reversed with the advent of civilization? As societies grow more complex, perhaps the average human has not had to know so much. He or she can ‘delegate’ tasks (not that such delegation is always voluntary). Perhaps civilization has made us dumber, not smarter.
Yes, the ‘great civilizations’ have made major contributions to the arts and sciences, typically through upper-class patronage of creative individuals—who otherwise would have to worry about their next meal. The down side, however, is that this emancipation of creativity requires a much larger number of helots. The latter also specialize in their own way—in doing the grunt work that others consider beneath them.
In the ancient world, intellectual life—the debating, pondering, and creating of new ideas—was confined to a small powerless minority, too few in number to generate the critical mass that makes intellectual ferment possible. There were no conferences, no academic journals, and no scientific associations. For the most part, there were only isolated individuals who felt estranged from the world around them. The more renowned ones had disciples in their entourage. But that was it.
This situation contrasts with that of Western Europe and then North America from the 17th century to the 20th. That intellectual ferment was broad-based. It took place within a large swath of the population that could understand the ideas being generated, and that could argue the pros and cons. It was this democratization of intellectual activity that made the West so exceptional.
I’m increasingly convinced that extreme social stratification—i.e., the creation of a small class of intellectuals and a much larger helot class—is inimical to true scientific progress. The intellectuals are too few in number, and too dependent on the system, to make any real contribution.