Tenuous support for the 20,000-year date came from a new source. Three samples from the gray sand were submitted for testing by a new approach to dating archaeological materials—a refinement of the “uranium-clock” technique by which very old rocks are dated. This, the so-called Rosholt method, is a measurement of the amounts of uranium and its products in radioactive disintegration that accumulate in bone or other material. A ratio is determined between two isotopes of uranium (U²³⁸ and U²³⁵) and such radioactive related products as protactinium (Pa²³¹), thorium (Th²³⁰), and radium (Ra²²⁶). The method is yet unproved and may have more sources of contamination or error than radiocarbon. The results of Rosholt measurement on Midland samples averaged 17,000, 18,000, and 20,000 years. The latter date was from a small section of the Midland skull itself. It must be reemphasized that this process is not established well enough, and the results here are not acceptable to the archaeologists who conducted the excavations.[42]
Radiocarbon dates that can be referred to Midland man and that are at the same time in keeping with local geology and paleontology and with regional archaeological perspectives indicate a probable age of perhaps 11,000 years.
Other Americans, not so early, are represented by the skeletal remains of an infant and three adults found in 1955 at Turin, Iowa. Parts of one adult skeleton and that of the infant were recovered by experts, under carefully controlled conditions, from a depth of about 15 feet. The adult had been partially exposed along the bank of a gravel pit. The associated gravels contained loess, a wind-blown deposit, indicating a cool climate and probable antiquity. The Turin skeletons have been dated in a roundabout manner. A projectile point associated with the infant bones seems identical with others found near Quimby, Iowa, with a radiocarbon date of just under 9,000 years.[43]
The physical remains of early man in the New World, no matter what primitive features they may display, must be considered essentially modern, clearly of the same species as ourselves. Our best clue to racial difference is the extreme longheadedness of the earlier types. Their skulls tend to differ from those of most modern Indians. Yet we can at least consider the possibility that they represented a racial type in contrast to that of the tribes most recently arrived from Asia.
The old skulls of the New World may not be entirely satisfactory proofs of the antiquity of early man in this hemisphere; for Tepexpan man and Minnesota man both have been challenged as intruders in an older soil. On the other hand, all the skulls except perhaps Tepexpan suggest to the partisans of glacial man in the Americas that the first immigrants were not “predominantly Indian in character.” They make an interesting and significant point. Can it be a mere coincidence that when we find a head which has been stepped on by an elephant, it is not round like most Indians’, but longer or narrower, and it has very heavy brow ridges? Can it be a coincidence that when we find a skull in a cave with the bones of extinct mammals, it has those same peculiarities? Can it be a coincidence that when we find a skull under rocklike hardpan or a distinctly ancient layer of soil, it has those unusual stigmata? It does no good to hunt up the skull of a Sioux or a Mound Builder or an Algonquin which looks like one from Punin or Florida or Lower California. That is not much better than finding the skull of a modern New Yorker that looks like one of early man’s—which you could do without too much trouble. If all Sioux skulls or Mound Builder skulls or Algonquin skulls were as archaic as all the Punin and Florida and Pericú skulls, or if some early skulls were short and broad, then the case for the Mongoloid Indian as the earliest man in America would be incontestable. But until we find a round-headed, thoroughly modern Mongoloid skull that has been stepped on by an elephant or got itself interred with a mammoth or buried under earth that ought not to be on top of it, we shall have to believe that the simon-pure Indian of Hrdlička’s idolatry was not the first American. We shall have to think that the archaic fellow from Punin or Florida or Lower California or the Lagoa Santa caves was our earliest man—and quite early at that. Just how early, the bones do not yet say.
7
THE ARTIFACTS OF EARLY MAN IN THE NEW WORLD
Artifact, oh, artifact!
Spear point or scraper or hand-axe—
First tool of man,
Ancestor of steam shovel and power lathe,