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. So we're going to start with diseases because without a doubt, I think this is going to have the most powerful impact on both worlds. And just so you know, before we tell the story, Old World wins. If we think about the peoples of the New World, these are people that came over the Bering Strait land bridge 10,000 years ago.