As far as transportation goes, we've got it pretty good. We can get around the world pretty quickly, if we so choose; our ability to hop in a plane and fly across the globe certainly comes in handy for business trips or quickie vacations. Or, we can use alternate strategies, as journalist Seth Stevenson did: for his book "Grounded," he opted to wind his way around the planet without using air travel. Along the way, he mused about the ways that transportation has evolved, and how our travel choices impact humanity. (Heavy topics, but he had plenty of time -- the trip took several months.)