the spread of language indicates has now been confirmed by genetic stud-
ies. Together they suggest that ancestors of the American Indians probably
began crossing to North America roughly 30,000 years ago. Climatologists
now believe that from about 60,000 years ago, Asia and North America
were joined at what is now the Bering Strait and archaeologists have found
evidence of human settlements in northeastern Siberia from about 40,000
years ago. So it was possible for humans and animals to walk across a land
bridge, which geologists call Beringia. They began to do so because,
although much of North America was covered by huge glaciers and sheets
of ice, parts of Alaska enjoyed a relatively mild climate. Even in the coldest
times, there was a corridor of relatively open countryside that channeled
movement of animals and men to the south. Then, about 10,000 years ago,
with the coming of what geologists term the Holocene, a warmer epoch, so
much ice melted that the sea rose as much as 120 meters and submerged
the land bridge. Those people who had already made the passage from
Asia profited from the melting of the vast sheets of ice to move inland and
further south. By about 14,000 years ago, some had reached Patagonia and
others had spread over both continents.
After their arrival in the New World, the speakers of Amerind spread
out across almost the whole of North and South America. Pockets of
other languages remained in the American Southwest and the Canadian
Northwest. These were derivatives of an Old World language now called
Na-Dene and were spoken in the far north of the continent where what is
known as Eskimo-Aleut was the common tongue. Then, for thousands of
years as families and small clans moved apart from one another, they
acquired different habits, adapted to different environments, and made
changes in the way they spoke. We can see how this process works by delv-
ing back into the past of our own language. Shakespeare’s English is intel-
ligible to us although it contains expressions we no longer understand.
Middle English, spoken a few centuries earlier, is arcane. Farther back
and farther away, English’s close cousins—Spanish, Italian, French, and
Portuguese—although sharing some vocabulary and much syntax and
grammar, were already largely foreign. If we move yet farther afield to
languages in our same Indo-European family, Russian, Persian, Greek,
Armenian, and Sanskrit appear almost totally alien. So it was with the
4 THE BIRTH OF AMERICA