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Scientists have confirmed for the first time that an important
component of early genetic material which has been found in meteorite
fragments is extraterrestrial in origin, in a paper published on 15
The finding suggests that parts of the raw materials to make the first molecules of DNA and RNA may have come from the stars.
The scientists, from Europe and the USA, say that their research
provides evidence that life’s raw materials came from sources beyond
The materials they have found include the molecules uracil and
xanthine, which are precursors to the molecules that make up DNA and
RNA, and are known as nucleobases.
The team discovered the molecules in rock fragments of the Murchison meteorite, which crashed in Australia in 1969.
They tested the meteorite material to determine whether the
molecules came from the solar system or were a result of contamination
when the meteorite landed on Earth.
The analysis shows that the nucleobases contain a heavy form of
carbon which could only have been formed in space. Materials formed on
Earth consist of a lighter variety of carbon.
Lead author Dr Zita Martins, of the Department of Earth Science and
Engineering at Imperial College London, says that the research may
provide another piece of evidence explaining the evolution of early
life. She says:
“We believe early life 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 4.5 billion years ago large numbers of rocks similar
to the Murchison meteorite rained down on Earth at the time when
primitive life was forming. The heavy bombardment would have dropped
large amounts of meteorite material to the surface on planets like
Earth and Mars.
Co-author Professor Mark Sephton, also of Imperial’s Department of
Earth Science and Engineering, 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 in objects from space, the
possibility of life springing forth wherever the right chemistry is
present becomes more likely.”
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