Are You Smarter Than a Caveman?

Not really sure, but our brains are shrinking

When it comes to brain size, bigger doesn't always mean better. As humans continue to evolve, scientists say our brains are actually getting smaller.

The downsizing of human brains is an evolutionary fact that took science writer Kathleen McAuliffe by surprise.

"I said, 'What?  I thought it was getting bigger!'" she tells NPR's Jacki Lyden. That was the story up to 20,000 years ago, she learned. Then, the brains of our ancestors reversed course and started getting smaller — and they've been shrinking ever since.

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," McAuliffe says.

So we don't really know if intelligence is tightly coupled to brain size.  Clearly, some intelligent people have smaller brains.  Women, in general have smaller brains than men (they are also generally smaller in stature), but just try to argue that women are less intelligent as a result.  I like the domestication angle:

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

Hare says when a population selects against aggression, they can be considered to be domesticated.  And for a variety of domesticated animals like apes, dogs or turkeys, you can see certain physical characteristics emerge. Among these traits are a lighter and more slender skeleton, a flattened forehead — and decreased brain size.

 Which explains the difference between Vikings and Metrosexuals...