Although the Columbian Exchange benefited both Europe and America by introducing new crops and types of livestock to each continent, the clash of cultures had some negative results as well. Most notably, the Columbian Exchange brought deadly diseases to the New World and its inhabitants. Diseases such as smallpox had been transmitted throughout the Old World, enabling its inhabitants to develop an immunity to them. However, Native Americans had no immunity to these diseases. Consequently, vast numbers of Native Americans suffered and died from smallpox and other similar Old World diseases when they encountered the European explorers and colonizers. Some researchers also think the Europeans may have contracted diseases from the Native Americans, too. Specifically, genetic evidence seems to indicate syphilis entered Europe through Columbus' voyages.