Monday, March 14, 2005
Dating Disaster
Two American researchers have dug up evidence that life's diversity on Earth gets periodically wiped out "in mysterious cycles of 62 million years for which science has no satisfactory explanation."
Physicists Richard Muller and Robert Rohde working at the U.S. Department of Energy's Lawrence Berkeley National Laboratory and the University of California at Berkeley have analyzed the fossils of 36,380 marine animals living over the past 542 million years. They discovered the cycle by creating an extensive computer database and analyzing the various genera. "What we're seeing is a real and very strong signal that the history of life on our planet has been shaped by a 62 million year cycle, but nothing in present evolutionary theory accounts for it," said Muller.
The researchers speculate that either periodic asteroid showers or cataclysmic volcanic eruptions may be behind the cyclical mass death. "My hunch, far from proven," Rohde said," is that every 62 million years the earth is releasing a burst of heat in the form of a plume formation event, and that when those plumes reach the surface they result in a major episode of flood volcanism. Such volcanism certainly has the potential to cause extinctions, but, right now there isn't enough geologic evidence to know whether flood basalts or plumes have been recurring at the right frequency."
Muller suspects comets. They "could be perturbed from the Oort cloud by the periodic passage of the solar system through molecular clouds, Galactic arms, or some other structure with strong gravitational influence," he said. "But there is no evidence even suggesting that such a structure exists."
Their report appears in the current issue of Nature
Physicists Richard Muller and Robert Rohde working at the U.S. Department of Energy's Lawrence Berkeley National Laboratory and the University of California at Berkeley have analyzed the fossils of 36,380 marine animals living over the past 542 million years. They discovered the cycle by creating an extensive computer database and analyzing the various genera. "What we're seeing is a real and very strong signal that the history of life on our planet has been shaped by a 62 million year cycle, but nothing in present evolutionary theory accounts for it," said Muller.
The researchers speculate that either periodic asteroid showers or cataclysmic volcanic eruptions may be behind the cyclical mass death. "My hunch, far from proven," Rohde said," is that every 62 million years the earth is releasing a burst of heat in the form of a plume formation event, and that when those plumes reach the surface they result in a major episode of flood volcanism. Such volcanism certainly has the potential to cause extinctions, but, right now there isn't enough geologic evidence to know whether flood basalts or plumes have been recurring at the right frequency."
Muller suspects comets. They "could be perturbed from the Oort cloud by the periodic passage of the solar system through molecular clouds, Galactic arms, or some other structure with strong gravitational influence," he said. "But there is no evidence even suggesting that such a structure exists."
Their report appears in the current issue of Nature
