Rapid climate change might have made us smarter

Today I watched all three parts of NOVA's "Becoming Human". I thought it was alright, but it did introduce me to some new things I hadn't heard about. One of them was that constant climate change of 2 million years ago might have actually increased our brain size.

From around 6 million to 2 million years ago, our line was becoming more bipedal but the size of our brain stayed relatively the same. Then the climate in Africa changed from wet to dry to wet in a span of about a thousand years. Only the most intelligent apes could have survived in this unstable environment, thus leading to what would become Homo habilis, nicknamed the "handy man" for his proficient use of stone tools. This was also the first species of the genus Homo.

So I guess Glenn Beck has one more excuse to casually dismiss today's climate change. Luckily, he probably won't be one of the humans to survive.