What Tipped? Facebook or Human History as we Know It?

The looming new year recently reminded me of something I read in June. It was a fact of human history with such a profound influence on the upcoming year that it may be the source of most of the changes of late and to come. For the first time ever, there will be more people in the world who live in cities than who don’t.
According to the United Nations Population Fund in June 2007, there are 3.3