Sea's Bounty, Not the Mammoth, May Have Drawn Nomads to Alaska
LEAD: A PREHISTORIC tableau is etched in the popular mind. On a bleak plain, hunters wrapped in animal skins and carrying spears lean into the frigid wind as they pursue the caribou and woolly mammoth; women and children follow them. These are the first migrants crossing from Asia to North America many thousands of years ago over the connecting bridge of land where the Bering
