Human brains are getting smaller, yet we’re supposedly smarter than our ancestors. Based on measurements of skull fossils found in Europe, the Middle East, and Asia, a recent study estimates that human brains have become about ten percent smaller, dropping about a tennis ball’s worth of total volume, over the past 30,000 years by evolutionary reckoning.
Researchers suggest that increased interaction and division of labor permitted humans with smaller brains to survive better. Just because our ancestors had larger brains, the scientists do not believe they were, on the whole, any smarter.
The Bible paints a different picture of human history. God created Adam and Eve “very good” in the beginning, with the full, unhindered ability to take dominion over the entire world. But sin brought a Curse and judgment upon mankind, including the darkening of our understanding.
Yet we see lots of evidence of amazing skills even among the earliest people groups, such as the builders of the pyramids. Another marvel is the Antikythera gear-driven computer device, found on a sunken ship from the second century BC. These artifacts indicate that our ancestors were just as intelligent as we are, or more so—and they apparently had bigger brains to show for it!
http://www.answersingenesis.org/articles/am/v6/n3/brain-shrink