Millions of years ago, geological forces ripped the world to pieces. Christopher Columbus changed all that though. When he sailed across the Atlantic, he began a process that knit the world back together ecologically and economically. It meant there would be tomatoes in Italy and coffee in Brazil. The journalist Charles Mann says while the costs and benefits are inseparable, 1493 marked the birth of the world we live in today. We spoke with Mann earlier this year about his book called "1493."