Some of these cosmic hitchhikers could have landed on Earth between 3.8 to 4.5 billion years ago, when the solar system was a tumultuous place and Earth was frequently pelted by violent flurries of comets and asteroids.
Alternatively, the nucleobases could have formed independently on Earth—but recent studies suggest the harsh conditions on early Earth might have made it difficult.
The research is detailed in the June 15 issue of the journal Earth and Planetary Science Letters.
Extraterrestrial Life
The new finding confirms what many scientists have long suspected, Berstein said.
"Knowing that [the molecules] form in space and are delivered to planets is clearly of great significance, because it suggests that some of the makings of DNA were drifting down on early Earth before, while, and after life was getting started and evolving," Berstein said.
The finding also has implications for extraterrestrial life, study leader Martins said.
"Meteorites may have delivered these building blocks not only to Earth, but also to other planets," she said.
"The meteorites were formed shortly after the birth of our solar system, so the material from the meteorites could be widespread through the universe."
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