I particularly liked this part:
" "Now you're able to put human evolution into a climatic framework. You can ask, Why did human beings not make civilization fifty thousand years ago? You know that they had just as big brains as we have today. When you put it in a climatic framework, you can say, Well, it was the ice age. And also this ice age was so climatically unstable that each time you had the beginning of a culture they had to move. Then comes the present interglacial—ten thousand years of very stable climate. The perfect conditions for agriculture. If you look at it, it's amazing. Civilizations in Persia, in China, and in India start at the same time, maybe six thousand years ago. They all developed writing and they all developed religion and they all built cities, all at the same time, because the climate was stable. I think that if the climate would have been stable fifty thousand years ago it would have started then. But they had no chance." "

Now I think it could have "something" to do with space rocks falling on our heads- "the sky is falling" - oh my!
:)