Of the books I’ve read so far this year, I find myself thinking more about one passage more than any others. It’s from a non-fiction book, Elizabeth Kolbert’s “Under a White Sky,” and it’s not the main theme of the book, which is about human efforts to manipulate the natural world to prevent things like flooding and the loss of species.  

We got to talking about climate history and human history. In Steffesen's view, these amounted to more or less the same thing. "If you look at the output of ice cores, it has really changed the picture of the world, our view of past climates and of human evolution," he told me. "Why did human beings not make civilization fifty thousand years ago?
 "You know that they had just as big brains as we have today," he went on. "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 beginnings 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 very 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."
**Side note: This isn’t meant to start a climate change debate, but I know that some might see it as evidence that the climate has changed cyclicly throughout time. No one would argue that—it’s been well known for decades and supported through geological evidence and ice core samples. But if you’re going to cite this, it would only be fair to note that over the past sixty-five million years, the rate of change since the Industrial Revolution has been about one hundred times faster than at any other time. Or you could just take the excerpt for what it is.