Research suggests the human brain is shrinking.

A Discover.com magazine feature by Kathleen McAuliffe drops a bombshell: Human brains are shrinking!

Anthropologist John Hawkes reveals that over the past 20,000 years, human male brains decreased from 1,500 to 1,350 cubic centimeters. Before you snicker, Hawkes adds that female brains also shrunk by a similar proportion.

One reason scientists aren't alarmed is the issue of scale. The ratio of brain volume to body mass is essentially the same for modern humans as it was for our larger predecessors: the Cro-Magnons. The reason? Larger animals require bigger brains to control more muscles. Simple, right?

Theories link shrinking human body size to an overall warmer global climate over tens of thousands of years. But evidence suggests our brains are shrinking faster than our bodies! One theory is that poor early agriculture initially led to chronic malnutrition as new grain-based diets were lower in protein, vitamins and amino acids compared to primitive meat-based diets. When we began farming, our brains starved.

A more intriguing explanation is that dense human settlements developed complex trade and division of labor. Brains became smaller because people didn't have to be as smart to survive!

Other anthropologists argue the opposite, saying our brains shrank as the "wiring" became more efficient.  In domesticating ourselves, we're in good company. All thirty species of now domesticated animals have lost 10% to 15% of their former brain volume.

It ALL makes my head hurt!