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Columbus Dispatch You might not be shocked to learn that science coverage by many media outlets tends to lean toward the extraordinary and sensational. So it was only natural that many took notice when a group of scientists recently reported that a comet smashed into northeastern North America 12,900 years ago, igniting catastrophic firestorms that wiped out dozens of species of giant mammals as well as the Ice Age Clovis culture that hunted them. Unfortunately, many did not follow up when further investigation shows claims like this are exaggerated or even entirely unfounded. Exploding comets and the deaths of millions of exotic animals are exciting; checking data and repeating analyses that might spoil the excitement are not. This focus on scientific "candy" at the expense of the "meat and vegetables" means that many people miss out on the scientific method. The so-called "Clovis comet" hypothesis was announced in 2007 and generated so much excitement that it was featured on the PBS science program NOVA in March. The proponents of the theory said that they had found evidence of a comet impact, including magnetic microspherules, in the earth overlying 10 Clovis-age archaeological sites across North America. University of Wyoming archaeologist Ted Surovell and several colleagues attempted to repeat the study and came up with startlingly different results. Their results appeared in the online edition of the Proceedings of the National Academy of Sciences in early October. They tested the Clovis comet hypothesis by examining seven additional sites to see whether the pattern was repeated on the continental scale cited by the previous investigators. Importantly, they also rechecked two of the same sites studied by the Clovis comet team. Using the same methods, Surovell and his co-researchers were "unable to find high concentrations of magnetic particles and spherules" - even at the two sites previously studied by the original researchers. In their conclusions, they rightly note that repeatability "is fundamental to the scientific method." If results can't be reproduced, then they "cannot be considered reliable or supportive of a hypothesis." One of the sites was Shawnee-Minisink, a Clovis period site located in northeastern Pennsylvania, relatively close to the proposed point of impact of the hypothetical comet. If the comet hypothesis is correct, then there should be abundant evidence there. In fact, Surovell and his team found no magnetic spherules at this site, or at the other two sites located in eastern North America. This story illustrates why the scientific method works so well. Scientists explore the universe, make discoveries and frame tentative explanations for the patterns they discern. Then they publish their conclusions in the scientific literature allowing other scientists working in the same discipline to challenge those ideas to see if they hold up to independent scrutiny. If they don't, then the ideas are revealed to be dead-ends or wrong turns. Perhaps original investigators unconsciously fudged data to see what they wanted to see. Perhaps there was conscious fraud. Regardless, the self-correcting nature of the scientific enterprise means that wrong turns are discovered and researchers are able to get back on the right track. I think this is a story that should be covered more often.
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