Scientists say genetic building blocks are from out of this world

June 20, 2008 A team of scientists from the United States, United Kingdom and the Netherlands have determined that chemicals that form the building blocks of DNA and RNA found in a meteorite had formed before the meteorite fell to Earth. In a paper published in Earth and Planetary Science Letters on June 15, the team documents an examination of molecules found in the Murchison meteorite, fragments of which landed near the village of Murchison, Victoria in Australia in 1969.

Previous studies had identified amino acids and sugars in the meteorite that were believed to have formed in space. The samples the current study examined included molecules of uracil and xanthine, which belong to the class of nucleobases - chemicals which, when combined with sugars, form a crucial part of DNA and RNA. These molecules contained a form of carbon, known as carbon 13, in much higher concentrations than would be expected if they had come from contamination through exposure from Earth sources. The study, using nuclear magnetic resonance (NMR) imaging, had not been undertaken before due to its laborious and time-consuming nature - the low concentration of nucleobases in the meteorite meant that 15 grams of space rock had to be processed to get a large enough sample, compared to the milligrams required for previous studies.

Co-author Dr Zita Martins, a chemist and astrobiologist from Imperial College London, believes their findings suggest that some of the chemicals that generated life on Earth came from meteorite bombardments. "We are not saying that only meteorites contributed to the building blocks of life," she said, "but it's a very great contribution." Other scientists, however, do not believe that meteoritic chemicals played such a significant role. According to Emeritus Professor Robert Shapiro of New York University, "They're a subunit of a subunit of DNA. My opinion is that their amounts were utterly unimportant and insignificant."

Wikinews contacted Professor Paul Davies, a physicist and astrobiologist presently at Arizona State University, about the recent findings. While he agreed with the findings, he said that he thinks such discoveries are "a red herring in the origin of life story - a hangover from the Miller-Urey experiment. Life is all about information - its replication and processing."