The Great Divide

may become relevant for the arguments in
     this book. The first mutation, at around 37,000 years ago, would, if it was so adaptive,
     presumably have spread quickly throughout Eurasia and included those early people who
     eventually migrated into the New World. Native Americans should, in other words, have
     possessed this allele. This is what research shows: microcephalin is virtually universal
     in New World populations.
    On the other hand, the second mutation, occurring roughly 6,000–
     5,000 years ago, would appear to have evolved after early men and women had
     crossed the Bering Strait, meaning that, in all probability, Native Americans should
     lack this development. And this too is what research shows: ASPM is completely absent in New World populations.
    It is too soon to say whether microcephalin or ASPM conferred some sort of cognitive advantage on those who possessed it, though its rapid
     spread suggests that is likely, although simple brain size appears to have remained
     stable. Nonetheless, this is clearly an area of potentially important genetic difference
     between Old World and New World peoples. We know from evidence in Iceland, which was
     inhabited only about a thousand years ago, that substantial genetic differences can
     arise in such a relatively short time frame, so it is not out of the question that some genetic variation accounts for the differences between the Old World and
     the New.
    That said, this area of science is still in its infancy, so no more will be
     made of it here, other than to draw attention to what is a tantalising possibility.
    One final thought on genetics. The relative lack of diversity among Native
     Americans, compared with the rest of the world, as shown by the Genographic Project and
     the Sijia Wang team study, may imply one of three scenarios. First, that there was at
     some stage a genetic ‘bottleneck’ in Beringia, where a small genetically
     limited group lived for a while, perhaps in a refuge surrounded by the ice, when they
     were forced to breed within their small community. Second, there was much polygamy
     later, with some – the more successful – men having several wives and
     others none (just such a pattern has been observed among the Dani population in Papua
     New Guinea, for example, where 29 per cent of the men had between two and nine wives,
     while 38 per cent had none). * Or again, a
     third possibility, it could be the result of widespread warfare, the burden of which was
     borne by men, leaving the remainder to father the children (among the Dani, again, 29
     per cent of men were observed to be killed by warfare). 13
    Among the consequences of such limited genetic diversity would have been the
     fact that the pace of evolution in the New World would have been slowed in comparison
     with that in the Old; and it would also have made New World peoples more susceptible to
     diseases introduced from outside.
     
    S LEDS AND S EAWEED
    The archaeological evidence for an entry into the New World from
     Siberia is supported by the great similarity of sites either side of the Bering Strait.
     A group of locations nearest to the Strait in Siberia was christened (in 1967) by Yuri
     Mochanov, a Russian archaeologist from the Scientific Research Institute at Yakutsk, as
     the ‘Dyukhtai culture’, after a site on the Aldan River, which flows north
     into the Laptev Sea, on the fringes of the Arctic Ocean. Here, mammoth and musk-ox
     remains were excavated, associated with spear and arrow points flaked on both sides, as
     well as blades and wedge- and disc-shaped cores – in other words, a distinctive
     upper Palaeolithic culture, dated to between 14,000 and 12,000 years ago. Other sites,
     with bifacial tools and blades and even knives, have since been found in the area,
     together with bone and ivory artefacts. Nothing older than 18,000 years has been
     unearthed, and the bulk of remains are later. The northern-most site of the Dyukhtai
     culture is found at Berelekh, near the mouth of the Indigirka River, on the northern
     shore of Siberia.
    Just as early people appear to have ‘beachcombed’ their way
     around the south-east coast of Eurasia, to reach China, so they may have beachcombed
     east from Berelekh along the Arctic Ocean coast of Siberia until they reached the Bering
     Strait – except that it was then land. Some palaeontologists, like Dale Guthrie,
     emeritus professor at the Institute of Arctic Biology at the University of