2.1 America: beginning to 8000 b.c.  (Page 2/3)

A slightly different view is given by Swanson et al (Ref. 209 ) who states that the first crossing of the Bering Strait occurred from 26,000 to 28,000 years ago and that these people became the American Indians with blood types chiefly O, with some A and no B. Then a second migration took place between 10,000 and 20,000 years ago which perhaps included the Eskimos who have AB and 0 blood types. They may have come by kayak from one shore to another as Eskimos today still live on both sides of the Bering Strait. By 10,000 B.C. prehistoric hunters were in all parts of the New World, even at Tierra del Fuego. Some fishing and gathering populations were very large. The highest average population density north of Mexico was in California where there were the acorn gatherers, a group which was so successful that they were not apt to experiment with new techniques. The most recent glaciation period in North America reached its maximum between 18,000 and 22,000 years ago and extended down to New York State and central Ohio, covering Minnesota, Wisconsin, Iowa, Illinois and parts of Kansas and Missouri. After 12,000 B.C. this retreated rapidly, sometimes several miles in a single year.

At 9,000 B.C. the American plains still teemed with giant bison, camels, stagmoose, musk-oxen, large cats, mastodons and three kinds of mammoths. Most of these were gone within 1,000 years of man's arrival. The dating of the flint spearheads of the Sandia Culture which have been found in Oregon, Ontario and New Mexico have been variously dated from 23,000 to 6,000 B.C. At any rate it was along the retreating ice edge, where the spruce forest and pines migrated north and west from the Appalachians and the oak moved north from the Gulf, that the increased parkland and grass allowed the human population, now with a radical new stone technology, to greatly increase. This was the time of the Great Hunting Culture, associated with the Clovis points of the Sandia Culture mentioned above. These Clovis points (so named because first identified near Clovis, New Mexico) were large, heavy flint points designed for hunting large animals, and butchered elephants have been excavated dating to the period 9,500 to 9,000 B.C. In some areas this culture, also sometimes called Llano, has been dated from 11,000 to 15,000 years ago. The Folsom spear points which developed from the Clovis were smaller and more delicately made, for effective use by the bison hunters.

As temperatures rose and the cloud cover diminished, there was an increased evaporation rate, the plant cover thinned and the great herds declined rapidly. Some feel that prior to the temperature rise the north-south corridor opened up in the glaciers allowing arctic winds to descend on the plains, and the sudden drop in temperature was a factor in the dying off of the giant bison and mastodons. The Desert Tradition of western North America, dating from about 9,000 B.C. was centered in the Great Basin of Nevada between the two great mountain chains and occupying portions of six present states - Nevada, Wyoming, Idaho, Oregon and California. Baskets and milling stones were made and the subsistence base included small seeds, berries, bulrush rhizomes and nuts.