The arrival of white men in America in 1492 does not only mean the clash of two different worlds. The Europeans change the nature and the life in the New World, also for their own benefit. It was the biggest exchange of cultures in the world history: plants, animals, bacteria, and genes were transported to and from America. For example, the Spanish brought their horses with them. Left on their own, the horses imbruted. Then they became important mounts for the Indians, who until then had only hunted on foot. The European domestic pig and certain plant species did not only bring positive effects. In addition, also the most cruel “conquerors” came along: the etiologic agents of variola and pestilence.