Our Brains Is Shrinking

This comes as no surprise to the Captain, who actually feels his brain atrophy every time he's forced to watch cable news on television.

Cro-Magnon man, who lived in Europe 20,000 to 30,000 years ago, had the biggest brains of any human species. In comparison, today's human brain is about 10 percent smaller. It's a chunk of brain matter "roughly equivalent to a tennis ball in size," [science writer Kathleen] McAuliffe says.

The experts aren't sure about the implications of this evolutionary trend. Some think it might be a dumbing-down process. One cognitive scientist, David Geary, argues that as human society grows increasingly complex, individuals don't need to be as intelligent in order to survive and reproduce.

But not all researchers are so pessimistic. Brian Hare, an anthropologist at the Duke University Institute for Brain Sciences, thinks the decrease in brain size is actually an evolutionary advantage.

"A smaller brain is the signature of selection against aggression," Hare tells [NPR's Jacki] Lyden. "Another way to say that is an increase in tolerance."

[...]

Hare does admit that the shrinking human brain could signal an evolutionary dumbing-down, but more important is what the phenomenon tells us about ourselves. Comparing our evolution to that of other animals enriches our understanding of the human condition.

"The nice thing about studying animals and human nature," Hare says, "is that it helps us design or think of some strategies that deal with our darker sides."

[NPR]