Some caring people may find the overkill model disquieting on a personal or spiritual level. They may feel it denigrates native people in those parts of the world, such as the Americas, where prehistoric extinctions appear to have been anthropogenic in origin. Being uncertain of the details and being aware that the vast majority of extinctions occurred before the existence of humans on the planet, social scientists may simply decide that environmental explanations must be the answer to the mystery of megafaunal extinctions. Climate change would be a prime example of a non-anthropogenic, environmental explanation.
In an extreme case, Native American anthropologist and activist Vine Delo-ria dismisses the scientific approach entirely. He treats a potential anthropogenic explanation for megafaunal extinction in America as a direct attack on his people's religious beliefs. Taking a position parallel to the Christian fundamentalists' explanation of the origins of humans, Deloria claims that the ancestors of America's Indians did not cross the Bering Land Bridge and discover a continent. Instead he asserts, "We were always here" (Deloria 1995). He urges that we look to the various Native American creation stories for answers to where the Native Americans' ancestors came from. Deloria rejects the notion that the First Americans exterminated the mammoths and other megafauna. Indeed he rejects what he characterizes as the Eurocentric science that supports the idea, including most of the fossil record and much of archaeology and biogeography. He dismisses radiocarbon dating, telling us that geochemists in radiocarbon labs are white liars who can invent dates.
This book is not the place to argue the relative merits of social scientific and scientific approaches to paleontology. Suffice it to say that I do not find Deloria's approach of any help in unraveling the mysteries of megafaunal extinctions.
Of course, no researcher is entitled to a free ride. Hoaxes, frauds, and counterfeits can plague paleontology (Tankersley 2002) as other disciplines, and when they do, it is important to acknowledge them as such. For example, archaeologist Frank Hibben claimed to have found what he named "Sandia points," allegedly older than Clovis points, at Sandia Cave, New Mexico. For some time Sandia points earned serious treatment by archaeologists, as in Ancient Man in North America (Wormington 1957), a popular book that long served as the final word on fluted-point archaeology. However, the dates originally assigned to the Sandia points have since been discredited (Preston 1995). Hoax or not, the existence of Sandia, or any other points older than Folsom and Clovis, has yet to be recognized.
In November 2000, prominent Japanese archaeologist Shinichi Fujimura, known as "God's Hands" because he was so successful at discovering early sites, was revealed to have planted at least some of them himself (G. Haynes 2002b).
The most famous hoax is Piltdown man, a human skull and an orangutan jaw, treated chemically to look like fossils of the same individual, discovered in England in 1911. Geochemistry, including radiocarbon dating, helped uncover the hoax decades later. The identity of the hoaxer, or hoaxers, remains a matter of speculation; discoverer Charles Dawson, famed paleontologist Sir Arthur Keith, and author Sir Arthur Conan Doyle (who lived near the discovery site) are among the many suspects.
As a final example, the University of Arizona radiocarbon laboratory found reason to believe that a sample submitted for dating of rock varnish might have been tampered with. Rock varnish is a veneer on many exposed rocks and boulders, especially in arid lands. Some imagined that it could be used in geochronol-ogy and claimed the dates supported pre-Clovis colonization of the Americas. The specimen the laboratory received for dating resembled a mixture of charcoal and coal. When split, the particles that looked like coal proved to be too old to measure by radiocarbon dating, as one would expect of coal. The material that looked like charcoal was modern. Charges of misconduct were contested by the plaintiff's lawyers and eventually settled out of court.
This unusual case underscores the obvious fact that providers of radiocarbon samples carry the burden of probity. Despite the pious hope that misconduct is less frequent among scientists than among lawyers, politicians, and loan sharks, no archaeologist can claim that his or her profession is totally immune from malpractice by those Tankersley (2002) calls "thieves of time."
But this is hardly an excuse for denouncing radiocarbon dating, with its increasingly refined methods of calibration. As long as investigators are free to challenge the findings of their peers, to demand repeatability of results, and to call for tests and test implications, we can expect progress toward understanding the secrets of the past, including the cause of megafaunal extinctions.
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