Like Australia, the New World was uninhabited by humans
(or any species
of ape) until the late Pleistocene. A glance at a map shows that they
were most likely to enter the Americas from the far north, since any
other point of entry would have required a willingness and capacity to
cross oceans with few island steppingstones. To the northeast the
distances between islands were less formidable than at lower latitudes,
but still demanded a seafaring ability that appeared only with the
Vikings (alias the Norsemen) in the late first millennium A.D.; and
even they had no discernible impact on the mainland of North America.
That leaves the northwest as the obvious gateway from Asia to the
Americas, though a rather peculiar one. It had to be negotiated in two
stages. First, the prospective immigrants had to wait for an ice age so
that the Bering Strait would turn into a land bridge and give them
access to Alaska. Then they had to wait until the ice age was over so
that glaciers blocking their movement to the south should melt. This
makes the end of the Pleistocene a plausible context for the human
occupation of the Americas.
We have no direct indication that this is what happened,
but the
indirect evidence fits. With regard to the route, genetic testimony
points strongly to affinities between the populations of the Americas
and those of Asia, especially Siberia. The date is more of a problem.
It is clear that northeast Asia was inhabited by 13,000 B.C. In Alaska
the oldest known sites go back to 11,000 or 12,000 B.C. Farther south
there is no dispute about the presence of humans by 11,000 B.C. But
earlier dates from various parts of the Ames
have their champions, and may yet prevail, though at
this point they
remain controversial. Of these earlier dates, that currently taken most
seriously would place the appearance of humans in the southern cone of
South America at about 12,500 B.C., implying a yet earlier date for
their initial arrival in North America. But the difference, though
highly significant for specialists, is hardly mind-blowing for the rest
of us. Whatever consensus develops, there is no real doubt that the
occupation of the Americas was a much later event than that of
Australia.
So what did these relatively recent immigrants make
of the Holocene
window in the Americas?
