I was intrigued by a story on the evening news earlier this week; so I stray from my usual subject matter.  The Earth’s population on October 31, 2011, officially reached 7 billion.  The story recounted the timeline for mankind reaching 1 billion and the subsequent billions and briefly touched on the challenges posed given today’s population density and its impact on planet resources.  The story started me thinking about our collective past and the future, and, specifically, what will our planet look like when our