Article

Extinction

Norman MacLeod

in Evolutionary Biology


Published online June 2016 | | DOI: https://dx.doi.org/10.1093/obo/9780199941728-0078

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In 1980 an interdisciplinary research team from the University of California, Berkeley made a startling announcement in the highly respected science journal/magazine Science (cited under Journals). This report detailed the discovery of evidence that the Earth had collided with a ten-kilometer asteroid at the very end of the Cretaceous period in Earth history. The article went on to speculate that this collision had probably been the cause of the extinctions that had long been known to have occurred at that time, including the extinction of the “dinosaurs.” This was not the first time scientists had proposed an explanation for this extinction event or the extinction of this group. Indeed, this was not even the first speculation that an asteroid collision had caused a major mass extinction. However, Luis and Walter Alvarez, Frank Asaro and Helen Michel were the first to claim to have direct, physical evidence of such a collision, the first to estimate the impactor’s size and speed, and the first to estimate the range of its physical effects. Reaction was swift, from virtually immediate acceptance that this long-standing mystery of science had at last been solved to entrenched opposition to the idea that an asteroid killed off the dinosaurs. It seemed that no one could ignore the implications of this announcement, certainly not the popular press, which seemed obsessed with the link between dinosaurs and space exploration. Since 1980, the asteroid impact theory of mass extinction has been debated widely in the technical and popular literature, has spawned many thousands of peer-reviewed research reports and presentations at scientific meetings, and has been the subject of dozens of international conferences, news stories, books, and videos. Along the way, this theory unquestionably changed the scientific community’s collective mind about which types of explanations can be considered scientific as well as which constitutes a “natural” process. Supporters and opponents alike have repeatedly declared the debate over; however, it remains one of the most active and high-profile contemporary scientific controversy holding the attention of the world in a way few other scientific debates have ever done. In addition, authors have linked both scientific and popular interest in the mass extinction events of Earth’s geological past with concern about the loss of biodiversity in the modern world, dubbing it the “sixth mass extinction.”

Article.  14314 words. 

Subjects: Evolutionary Biology

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