Were Europeans the only explorers?

This depends on one's definition of exploration. There are some that claim that Polynesians arrived in the New World well before the earliest artifacts from the Bering Strait land bridge. Others claim that the earliest Americans have more in common genetically with early hunters from mainland Asia. These early groups, whether they came via land bridge or whaleboat, can be considered the first explorers of the New World, as they arrived to a land that was untouched and plentiful with game. Not much is known about their arrival, and they are currently a popular topic in anthropology and archaeology. Charles C. Mann has written a series of books on the topic of early Americans and how they interacted with their environment, the first of which is titled 1491. The book describes the culture of early Americans and shows that they were not passive inhabitants of the New World; rather, they adapted the new land to meet their needs in ways similar to what Europeans would do centuries later.