The Great Divide

20,000
     years ago have ever been found anywhere in Siberia. However, there is both genetic and
     linguistic evidence for an earlier entry into the New World. This evidence is
     controversial and is not universally accepted. The location of the sites is important
     because agriculture has never been successfully practised this far north and so early
     man could not have entered the New World knowing anything of agriculture. This is in
     itself not surprising for agriculture did not emerge anywhere on earth until about
     10,000 years ago but at least that means this is one area where the picture is clear:
     the Old World and the New both lacked agriculture when the Great Divide took place
     (though they had dogs).
    The DNA evidence shows that the Chukchi are
     genetically distinctive. According to the Genographic Project (see below), they have a
     marker, a distinctive pattern of genes, technically known as M242, and other
     characteristics, which show that they originated in a single man living about 20,000
     years ago in southern Siberia or Central Asia. These markers are also shared with Native
     Americans as far south as Tierra del Fuego and therefore confirm – for
     geneticists – that early man entered the New World from Siberia some time after
     20,000 years ago. 3
    This picture was supported – and amplified – when the first
     results came in from the Genographic Project, set up in 2005, sponsored by National
     Geographic but making use of IBM’s massive computational skills. This very large
     study examined the DNA of around 150,000 individuals on five
     continents, to draw up the most thorough picture of our genetic history ever mounted.
     The most basic technique of the Genographic Project was to examine what are termed
     haplogroups, distinctive and characteristic patterns of genetic mutation, which comprise
     ‘markers’ on mt DNA or Y-chromosomes and which show
     how people are related and were related in the past (M242 is a haplogroup).
    This research shows two things that concern us. First, that today’s
     Native American peoples are very similar to one another genetically and that most of the
     distinctive markers are somewhere between 20,000 and 10,000 years old, clustering around
     the 16,000–15,000-year mark. The significance of this timing is that it was
     during what is called the Last Glacial Maximum ( LGM ), the era
     – between 20,000 and 14,000 years ago – when the vast glaciers of the last
     Ice Age reached their greatest extent, when sea levels were 400 feet below where they
     are now, and when the Bering Strait would have comprised a land bridge between Siberia
     and Alaska.
    One haplogroup located on the Y-chromosome is found in Native American men
     living all the way from Alaska to Argentina and, together with another haplogroup
     descended from it, is almost the only Y-chromosome lineage found in South America. 4 In
     western North America there is another lineage, which appears to have arrived in the New
     World later and never to have got as far as South America. But between them, these
     markers account for 99 per cent of Native American Y-chromosomes. On top of that, there
     are only five mt DNA haplogroups in Native Americans, in marked
     contrast to the dozens of mt DNA and Y-chromosome lineages
     found in Eurasia and Africa. 5 An important point about the second lineage, the
     one found in western North America and known as haplogroup M130, is that it is also
     found in South East Asia and in Australia, suggesting that this second , later
     migration into the Americas comprised people who travelled up the Pacific rim, the east
     coast of Asia and entered the New World around 8,000 years ago, when the Bering Strait
     was again submerged. They therefore must have migrated by boat. This lineage typically
     appears in Indians speaking Na-Dene languages, the second major linguistic family of
     North America (see below).
    The third piece of evidence was another large inquiry, published in 2007, by
     a team of twenty-seven geneticists from nine countries coordinated by Sijia Wang from
     Harvard. 6 This team examined the genetic markers in 422
     individuals representing 24 Native American populations in North, Central and South
     America and compared them with 54 other indigenous populations world-wide. The main
     results of this study were as follows:
     
they found that Native American populations have lower genetic diversity and greater
     differentiation than