Researchers discovered the organic molecules uracil and xanthine in the meteorite and confirmed they could not have formed on Earth. These molecules, called nucleobases, are precursors to DNA, a set of genetic instructions for organisms on Earth. Uracil and xanthine may also have been stepping-stones to RNA, which builds proteins in organisms.“Emergent life systems may have adopted nucleobases from meteoritic fragments for use in an early and primitive genetic material, enabling them to pass on their successful features to the next generations,” said study leader Zita Martins of Imperial College London. The finding supports an idea first proposed by astronomer Carl Sagan and a colleague in 1992. Some of life’s crucial building blocks, they said, were forged in the hearts of roving comets and asteroids, which seeded them throughout the cosmos.
from: National Geographic