6 INTRODUCTION The first peoples to explore and settle the Americas were the ancestors of the American Indians These early explorers were members of nomadic hunter-gatherer cultural groups They moved from Asia to North America during the last ice age when thick ice sheets cov ered much of northern North America As the ice sheets absorbed water sea levels dropped and a land bridge emerged along what is now the Bering Strait From about 30,000 to 12,000 years ago this land bridge connected northeastern Asia to what is now Alaska Some peoples came to North America by fol lowing the Pacific coast southward They may have combined walking with boat travel Others walked across a glacier free area through the center of what is now Canada 6
Scientists call the now-underwater stretch of land that the ancestors of the American Indians crossed the Bering Land Bridge This image by a modern artist shows a group of hunter-gatherers crossing it Continued melting of the ice gradually opened up the land allowing people to spread out across North America and into South America No single person made any large part of the long journey one group after another continued the march over many centuries The first Europeans did not arrive in the 7 INTRODUCTION
8 THE AGE OF EXPLOR ATION Americas until many thousands of years later By that time the Indians had explored and settled all portions of what the Europeans would call the New World Europeans rediscovered the Americas during the period of maritime exploration known as the Age of Exploration which began in the late 15th century During this period Europeans also explored the coasts of Africa sent ships directly to India and Southeast Asia and sailed around the globe European exploration ushered in globalization the development of economic and cultural links throughout the world Europeans conquered and colonized distant lands establishing vast empires In the Americas violent conquest and diseases acciden tally brought over by the Europeans killed enormous numbers of Indians Smallpox yellow fever malaria influenza and measles were among the diseases spread to the New World Indian populations fur ther decreased as Europeans forced them to work on plantations and in mines under harsh conditions Europeans later imported African slaves to replace the Indians as a labor source Meanwhile gold and silver poured back to Europe from the mines enrich ing European economies European exploration led to the exchange of plants animals germs technologies and ideas across continents in what is now called the Columbian Exchange after Christopher Columbus Potatoes corn tomatoes sweet potatoes squash cassava
INTRODUCTION 9 In the Columbian Exchange numerous plants animals and microbes from Europe Asia and Africa were introduced to the Americas and numerous others were transferred from the Americas to Europe Asia and Africa
