The human brain is shrinking. Scientists say that over the past 20,000 years we've lost the equivalent of a tennis ball's worth of brain matter.
For the first two million years of our existence our brains were steadily growing larger but brain size has seen an incredibly steep decline in our recent evolutionary history.
Paleoneurologists are in two camps regarding why this is happening. Some say were getting dumber, while others think our brain is becoming more efficient, without losing any essential cognitive components.
The brain burns up 20% of our caloric intake so size reduction could prove beneficial. Then again, being able to work a doorknob comes in handy as well.
Personally, I think the idea of human beings getting stupider is fundamentally preposterous. Now if you'll excuse me, this bucket of paste isn't going to eat itself.