Thanks for passing this on, even if this short piece is, in my view, rather misleading! Whether it is so because of the inability of the “science writer” to comprehend the exact nature of the archaeological (in this case, Pedra Furada’s) record, or because he was misinformed, led astray, disinformed, etc. by the researchers he consulted, is for you to decide.
At any rate, it is a good occasion to comment on a few rather incorrect statements.
ROCK OF AGES
Method developed at A&M challenges claims over cave paintings
By ERIC BERGER
Copyright 2003 Houston Chronicle Science Writer
HOW PLASMA
EXTRACTION WORKS
• Scientists must delicately collect the limited quantities of carbon embedded in inorganic paints on cave walls to date them with radiocarbon methods.
• Texas A&M researchers have developed a method that injects oxygen heated to 300 degrees into a pigment sample, knocking out carbon without destroying it.
• The method allows such small samples of paint to be dated that determining the age of an ancient cave painting is now possible.
They are pictures of people, deer, llamas, crocodiles and even pumas.
There are more than 350 stone walls filled with such paintings at Pedra Furada, a prehistoric site in a remote area of Brazil. They also may be the oldest cave paintings ever found in the Americas, and their discovery could radically change scientists' understanding of how and when the first people came to this hemisphere.
The problem is, a Texas scientist says the paintings, drawn with charcoal and other pigments, are not 30,000 years old, as a team of archaeologists led by Brazilian Niéde Guidon there claim, but just a few thousand years old.
For starters, the title is just another example of pure, unaldurated hype (or, perhaps, just plain confusion) in which the method(s), the material(s) being dated, and the purpose(s) of dating are completely mixed up. In all fairness to the author, it reflects well large portions of the article.
As far as I can recollect,, the Brazilian “team” has never claimed (on the basis of actual evidence) that the “paintings” dated back to 30 ka. The bulk of the rock art (paintings) identified at Pedra Furada – but for one exception, see below) -- admittedly spans the Holocene age and has been presented as such – with dates -- by the Brazilian researchers. Whether the Brazilian dates are based on a method that is in need of refinement is another story altogether and, for all I know, the Texas A&M new method may, indeed be more accurate in terms of “contamination proof” (as it were) than others, when dealing with, primarily, mineral pigments.
The exception I mentioned above consists of a rock slab or tablet fragment that exhibits (culturally) coloured markings and that likely fell down from the shelter wall. It happens to have been found buried in a level that has been dated in the 16-17 ka range, and this from charcoal remains coming from a hearth (?) and asscociated with artefacts. Assuming reliable chrono-stratigraphic controls, this implies that there were people at Pedra Furada who were, at or before 16-17 ka, into decorating their rock shelter(s). And unless it can be demonstrated that the painted rock slab and/or the charcoal date is wrong, a human presence in the Brazilian Nordeste, at the end the of the Upper Pleniglacial, remains a perfectly valid proposition.
Many of the other dates (close to 50 of them) that have served to make Pedra Furada controversial, have nothing directly to do with “paintings”. They were, for the most part, obtained from charcoal extracted from features identified (by the “Brazilian team”) as “hearths”, and they range from the end of the Upper Pleniclacial to around 50 ka. Furthermore, some of these well dated depositional units also happened to have yielded stone artefacts that, unfortunately, happen not to be “readable” by many, if not most North American (i.e., US) archaeologists.
In other words, trying to tie in the admittedly real difficulties in direct rock art/mineral pigment dating to the actual full cultural sequence that has been proposed for Pedra Furada is, at the very lest a rather inelegant red herring of a type that doesn’t serve the credibility of interdisciplinary palaeoanthropology.
This said, I am also looking forward to reading an actual paper on these recent dating advances.
Jacques Cinq-Mars
