And over that 175 million years, they're going to grow up differently, ecologically, evolutionary. And in 1972, a young man by the name of Alfred W. Crosby, he might have been old, from the University of Texas at Austin wrote a book called The Columbian Exchange, where he wrote about the tremendous effects that occurred when these two worlds, the Old World and the New World, clashed, came together. Not always intended consequences, sometimes unintended consequences, but they shaped the world we know today. They are revolutionary in the sense that they're going to change everything. And really, we're going to be talking about three different factors that are going to cause the effects. That's going to be plants, animals, and diseases. So why don't we take a look at all three and see if we can figure out why the Columbian Exchange is going to be on the test.