6
MAPPING THE PAST
Debate over the Earliest
Route to the Americas
Lake BaikalARCTIC
OCEANASIA
40,000 BPJAPANLaurentide
Ice SheetBering
Land BridgeSiberiaApproximate coastline
during maximum
glacial extentCordilleran
Ice Sheet
Fairbanks
Alaska
Kennewick
Washington
12,000 BPIce-free corridor
passable about
12,000 BPCordilleran and Laurentide ice sheets to create a gap
between the two—an ice-free corridor leading to present-
day Calgary and the Great Plains. The discovery of
advanced hunting blades and skeletons at Clovis, New
Mexico, dating from around this period, seemingly con-
firmed this thesis.
But during the past decade, human skeletons older
than this have been found in the Americas: Those in
Meadowcraft, Pennsylvania, in Cactus Hill, Virginia, and in
Topper, South Carolina, presumably date from around
16,000 BP (before the present) or earlier. Most puzzling is a
site containing evidence of human occupation in Monte
Verde, Chile, which some archaeologists date from 30,000 BP.
If the ice-free corridor from Alaska had not opened
until 13,000 BP, how did peoples get to Pennsylvania,
Virginia, South Carolina, and southern Chile thousands of
years earlier?
In recent years, some scholars propose that there have
been multiple migrations from Asia into the Americas, per-
haps the first as early as 30,000 years ago. Nearly everyone
agrees that the ice sheets of Canada would have been
impassable, but the discovery of ancient skeletons along the
Pacific coast has given rise to the thesis that the first Paleo-
Indians made their way down the Pacific coast. This conclu-
sion is strengthened by DNA analysis that suggests thatS
cientists have determined that many of the oldest skele-
tons in the Americas were genetically similar to ancient
skeletons found in the Lake Baikal region of Siberia. Scholars
hypothesize that about 30,000 years ago people from the
Baikal area moved north and east, likely in pursuit of big
mammals, and eventually crossed the Bering Strait to Alaska.
This was during the last ice age, when so much water had
been captured as glacial ice that ocean levels were hundreds
of feet lower than they are today. These roaming hunters did
not know they had entered a new continent.
As they reached what is now Fairbanks, Alaska, they
came upon the massive Cordilleran Ice Sheet and, farther
east, the Laurentide Ice Sheet. That early peoples could have
made their way across so formidable an obstacle, or would
even have wished to do so, seems doubtful.
Until recently, most scholars believe that around
12,000 years ago, global warming melted enough of the