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Niall001 
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 Posted: Thu Nov 04, 2004 2:09 pm Post subject: Stardust mystery ingredient in Humans
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Stunning Find Deep in the Pacific Ocean
Ancient star dust found deep beneath the Pacific Ocean has led German scientists to make an astounding conclusion. They think it points to our human origins.
Researchers from the Technical University of Munich in Germany surmise that the star dust is likely debris from a supernova explosion that occurred some 3 million years ago, reports Reuters. The explosion rocked the Earth so much that it changed our planet's climate--drastically heating it up--and helped bring about human evolution just as our ancestors started to walk.
Study leader Gunther Korschinek speculates that the supernova may have caused an increase in cosmic rays for about 300,000 years, which would have warmed up the Earth's temperatures. Korschinek can tell that the star explosion occurred at the same time there was a significant climate change in Africa when drier conditions caused the forests to retreat and the savannah to emerge, reports Reuters. It's this major climate change that likely caused the hominids to emerge from the trees and begin to walk upright.
Five years ago, Korschinek and his team found star dust in Pacific sediments. This time they looked at a site much deeper in the Pacific Ocean near the equator but away from land. At 15,750 feet below the surface, they found a layer of iron-60, which was stable and easy to date. The age? About 2.8 million years old.
Reuters explains that iron-60 is an isotope or chemical variant of iron that is rare on Earth--so rare that scientists are in general agreement that it is unlikely to have come from anything other than a supernova. Iron-60 has a decay rate or half-life of about 1.5 million years, so it's easy to nail down when the star exploded. A bombardment of cosmic rays caused by a supernova explosion could affect the ozone layer, which would have let in more of the Sun's ultraviolet rays. And that would make it hotter and drier on some places on Earth.
Here's the catch: "It has not yet been established that such an increase of the cosmic ray intensity could have had a significant influence on the Earth's climate," the research team wrote in the journal Physical Review Letters. But there is a coincidence. "The African climate shifted toward more arid conditions about 2.8 million years ago," they wrote, adding, "some of the major events in early hominid evolution appear to be coeval with the African climate changes."
We may walk upright today because of a supernova explosion almost 3 million years ago.
cnn.aimtoday.cnn.com/news...t/stardust |
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