French archeologists (not American) have established to the satisfaction of most European archeologists (not American) that humans were present in Brazil at least 50,000 years ago. F. Parenti, with N. Guidon, presented their data at a recent Paris meeting. The main site studied was the sandstone rock shelter of Pedra Furada, which is one of several hundred painted rock shelters discovered in northeastern Brazil. Guidon began her work in 1978; Parenti, in 1984. The fourvolume, 7-kilogram report (actually Parenti's doctoral thesis) concentrates on three lines of evidence:
A coherent series of 54 radiocarbon dates ranging from 5,000 to 50,000 years.
Crudely flaked stones, some 6,000 of which are deemed of human manufacture, even when the most stringent criteria are applied. Many of these came from Pleistocene strata 50,000 years old or older.
Some 50 Pleistocene "structures" consisting of artificial arrangements of stones, some burned, some accompanied by charcoal. These are likely ancient hearths.
(Bahn, Paul G.; "50,000-Year-Old Americans of Pedra Furada," Nature, 362:114, 1993.)
Comment. With the Brazil and Chile (Monte Verde) sites looking more and more convincing, it is reasonable to ask why even older sites have not been found in North America, which is nearer the famous Bering Land Bridge. As a matter of fact, controverted human artifacts have been found at such sites as Calico Hills, California, which are claimed to be much older than 50,000 years. It will be interesting to see how the Pedra Furada data are received in the States.
Just like there has been a revolution in paleontology during the last sixty years because we are learning what to look for and where, I think your non conforming archaeological finds are because we are now willing to look for them. Excellent posts.