Life from meteors?
Some of the major building blocks for complex biological molecules may have arrived from the solar system or beyond, according to a new study. The evidence shows up in shards from the Murchison meteorite, which landed Down Under in 1969.Skip to next paragraph
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The idea that complex prebiotic chemicals could have come from space isn’t new. Other teams have shown that other biologically important acids hitched a ride on the Murchison meteorite. The smoking gun: The acids were enriched with the isotope carbon-13, compared with the same acids in terrestrial organisms.
Meanwhile, researchers have tested fragments from various meteorites for so-called nucleobases. These combine to form nucleotides, which in turn form DNA and RNA. The ultimate questions: Did these two biological heavy hitters form strictly from homegrown ingredients? Or did some of the more-complex biochemical middle-men arrive, premixed, via comets and asteroids?
The evidence has been ambiguous; others have shown how the nucleobases could be present either from contamination after the meteorite struck Earth or as a byproduct of the techniques used to detect the nucleobases in the lab. A team led by Zita Martins of Britain’s Imperial College analyzed two nucleobases found in the Murchison meteorite – uracil and xanthine – and paid close attention to carbon-13. The team found that Murchison nucleobases also were heavy on carbon-13, compared with their terrestrial counterparts, indicating an extraterrestrial source. The results appear in the current issue of Earth and Planetary Science Letters.