Radioactive dating sparks controversy

By measuring the remaining amount of carbon-14 in a sample, scientists could estimate the time of death up to 60,000 years ago.Before that, all traces of radiocarbon would be too small to detect.The analysis, conducted by James Paces of the United States Geological Survey, pointed to a “burial date of 130.7 ± 9.4 thousand years ago.” into the Americas.” Who these people were, or when or where they came from, the authors do not venture to guess. 4: The Indisputable Facts in the Artifacts The findings and conclusion have led to strong protests from the archeological community.The primary rebuttal is that the bones could have been smashed by other causes. Holliday, an archaeologist at the University of Arizona, argues that the authors “don’t demonstrate that they could only be broken by humans.” Southern Methodist University archaeologist David Meltzer similarly says that “you cannot take broken bones and nondescript stones to make the case, not without demonstrating that nature could not have broken those bones and modified those stones.” Some archeologists, like Gary Haynes of the University of Nevada Reno argued that it could have been the bulldozers, which “weigh seven to fifteen tons or more, and their weight on the sediments would have crushed bones and rocks against each other.” However, if the evidence in the report is correct, that the mastodon was freshly killed when the bones were smashed, it rules out the bulldozers and begs the question, if humans didn’t do it, what did? Deméré argued that, “It’s kind of hard to envision a carnivore strong enough to break a mastodon leg bone.” Other archeologists, such as Michael Waters of Texas A&M’s Center for the Study of the First Americans, feel that the stones described in the paper do not unequivocally look like tools. Andrew Hemmings, from Florida Atlantic University, says it is not clear what the humans, if they were humans, were doing, given that a mastodon tooth was shattered along with bones."The radiocarbon dating technique may significantly underestimate the age of sediment for samples older than 30,000 years,” said the authors of the report from the Chinese Academy of Sciences and Germany’s Leibniz Institute for Applied Geophysics.“Thus it is necessary to pay [special] attention when using such old carbon data for palaeoclimatic or archaeological interpretations," they added.Their work was detailed in a paper in the latest issue of the journal .

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But as soon as the creature dies it stops absorbing these and sheds any trace of carbon-14 at a decay rate of 50 per cent every 5,700 years.As scientists who study earth’s (relatively) modern history rely on this measurement tool to place their findings in the correct time period, the discovery that it is unreliable could put some in a quandary.For instance, remnants of organic matter formerly held up as solid evidence of the most recent, large-scale global warming event some 40,000 years ago may actually date back far earlier to a previous ice age.But the method had one major flaw: it didn’t account for changes in the proportion of radioactive and non-radioactive carbon in the environment; and if these had changed, the estimate would most likely be wrong.Many events can affect the levels of carbon-14 in the atmosphere, such as the burning of fossil fuel or the detonation of an atom bomb.

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