may have been long before that. And experts are testing contentious theories regarding how they got here, including the idea of a dangerous canoe-born voyage from Asia down the west coat of the Americas, or even across the Atlantic from Europe. Since 1932 and the discovery of ancient weapons at Clovis, New Mexico, the "Clovis-first" theory held that Ice Age big-game hunters entered the continent by crossing a land bridge that spanned the Bering Strait between Asia and Alaska. Then archaeologists discovered a problem: massive ice sheets blocked the way south, and the search for an alternative explanation began. NOVA investigates controversial clues, including finds in an Alaskan bear cave hinting at a west coast voyage, and a st...  (less)