Windsor Humanist Society

June 15, 2008

Genetic Coding in Meteorite Played Key Role in Life on Earth

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Genetic material from outer space found in a meteorite in Australia may well have played a key role in the origin of life on Earth, according to a study to be published Sunday.

MeteoriteEuropean and U.S. scientists have proved for the first time that two bits of genetic coding, called nucleobases, contained in the meteor fragment, are truly extraterrestrial.

Previous studies had suggested that the space rocks, which hit Earth some 40 years ago, might have been contaminated upon impact.

Both of the molecules identified, uracil and xanthine, “are present in our DNA and RNA,” said lead author Zita Martins, a researcher at Imperial College London.

RNA, or ribonucleic acid, is another key part of the genetic coding that makes up our bodies.

These molecules would also have been essential to the still-mysterious alchemy that somehow gave rise, some four billion years ago, to life itself.

“We know that meteorites very similar to the Murchison meteorite, which is the one we analyzed, were delivering the building blocks of life to Earth 3.8 to 4.5 billion years ago,” Zita Martins said.

Competing theories suggest that nucleobases were synthesized closer to home, but Zita Martins counters that the atmospheric conditions of early Earth would have rendered that process difficult or impossible. A team of European and U.S. scientists showed that the two types of molecules in the Australian meteorite contained a heavy form of carbon — carbon 13 — which could only have been formed in space.

“We believe early life may have adopted nucleobases from meteoric fragments for use in genetic coding, enabling them to pass on their successful features to subsequent generations,” Zita Martins said.

If so, this would have been the start of an evolutionary process leading over billions of years to all the flora and fauna — including human beings — in existence today. The study also has implications for life on other planets. “Because meteorities represent leftover materials from the formation of the solar system, the key components of life – including nucleobases – could be widespread in the cosmos,” said co-author Mark Sephton.
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…this post forwarded by Windsor Humanist, Matt Achine, after a June 14, 2008 article in Agence France-Presse

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