Origins & Settlement Patterns INFORMATION

Dressed in warm, tailored hide garments stitched together with sinew and bone needles and armed with an expert knowledge of nature, the ancestors of the Paleo-Americans entered an Arctic world without parallel today.  The ice sheets in northern Europe and North America had locked up vast quantities of water, lowering sea level by more than 100 meters and exposing the continental shelves of northeastern Asia and Alaska.  These newly revealed lands, together with adjacent regions in Sibera, Alaska and norther Canada, formed a landmass that joined the Old World seamlessly to the New.

Known today as Beringia, this landmass would have made a welcoming way station for pre-Clovis migrants.  The air masses that swept over it were so dry they brought little snowfall, preventing the growth of ice sheets.  As a result, grasses, sedges and other cold-adapted plants thrived there, as shown by plan remains found preserved under a layer of volcanic ash in northwestern Alaska and in the frozen intestines of large herbivores that once grazed in Beringia.  These plans formed an arid tundra-grassland, and there woolly mammoths weighing as much as nine tons grazed, as did giant ground sloths, steppe bison, musk ox and caribou.  Genetic studies of modern Steller's sea lion populations suggest that this sea mammal likely hauled out on the rocks along Beringia's island-studded south shore.  So the migrants may have had their pick not only of land mammals but also of water ones.

Received wisdom holds that the trailblazers hurried across Beringia to reach warmer, more hospitable lands.  Some researchers, however, think the journey could have been a more leisurely affair.  The major genetic lineages of Native Americans possess many widespread founding haplotypes -- combinations of closely linked DNA sequences on individual chromosomes that are othen inherited together -- that their closes Asian kin lack.  This suggests that the earliest Americans paused somewhere en route to the New World, evolving in isolation for thousands of years before entering the Americas.  The most likely spot for this is Beringia.  There the migrants could have been cut off from their Asian kin as the climate cooled some 22,000 years ago, forcing Siberian bands to retreat south.

Whether the migrants cooled their heels in Beringia, however, or somewhere else in northeastern Asia, people eventaully began striking off farther east and south.  A warming trend began slowly shrinking North America's ice sheets some 19,000 years ago, gradually creating two passable routes to the south and opening the possibility of multiple early migrations.  According to several studies conducted over the past decade on the geographic distribution of genetic diversity in modern indigenous Americans, the earliest of these migrants started colonizing the New World between 18,000 and 15,000 years ago.