It is not every day that you discover your ancestors were alien, but to Zita Martins and Mark Sephton in ESE the realisation came with the analysis of a carbon-rich meteorite called Murchison.
Martins’ and Sephton’s Alien Origins
It is not every day that you discover your ancestors were alien, but to Zita Martins and Mark Sephton in ESE the realisation came with the analysis of a carbon-rich meteorite called Murchison. The meteorite fell in Australia in 1969 and previous analyses have shown that it contains a huge variety of organic compounds from hydrocarbons to coal-like macromolecular material. Amongst these molecules are nucleobases, compounds which are precursors to the molecules that make up DNA and RNA, the fundamental genetic units of all known living organisms.
The presence of nucleobases in the Murchison meteorite suggest that perhaps meteorites, which showered the early Earth, provided the basic building blocks from which the first living organisms were constructed. However, there was an alternative explanation, the Murchison meteorite fell in a farmyard and it was possible that the small amounts of nucleobases it contains had very terrestrial and quite smelly farmyard origin.
To prove whether nucleobases within Murchison were indigenous extraterrestrial molecules or cow-derived contamination Martins and Sephton isolated uracil and xanthine from the meteorite and using world-leading GC-QMS analyses measured the carbon isotope ratios of the molecules. Extraterrestrial organic molecules are isotopically heavier than their terrestrial counterparts having higher abundances of carbon-13 compared with carbon-12. The results confirmed that Murchison’s nucleobases are from space.
The results of the study have been published in a paper in Earth and Planetary Science Letters. Lead author Dr Zita Martins says that the research may provide evidence explaining the evolution of early life. She says:
“We believe early ife may have adopted nucleobases from meteoritic fragments for use in genetic coding which enabled them to pass on their successful features to subsequent generations.”
Between 3.8 to 4.4 billion years ago large numbers of rocks similar to the Murchison meteorite rained down on Earth at the time when primitive life was first forming. The heavy bombardment would have dropped large amounts of meteorite material to the surface of planets like Earth and Mars.
Co-author Professor Mark Sephton, also of ESE, believes this research is an important step in understanding how early life might have evolved. He added:
“Because meteorites represent left over materials from the formation of the solar system, the key components for life – including nucleobases – could be widespread in the cosmos. As more and more of life’s raw materials are discovered from space, the possibility of life springing forth wherever the right chemistry is present becomes more likely.”
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