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Image credit: B. K. D. Pearce

Meteorites may have helped seed life on Earth

A new quantitative model suggests they delivered organic molecules crucial for RNA self-replication.
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B. K. D. Pearce

There are many theories about how life evolved on the planet Earth, from formation under a layer of ice, protected from the UV radiation above, to vents in the deep sea that provided hydrogen-rich molecules. But now one team of scientists has found quantitative results that support a theory that is literally out of this world. Organic molecules from meteorites that landed in small, warm pools of water may have delivered the ingredients necessary for life to form on Earth.

The team reached this conclusion through a mathematical model. They took data about planet formation, geology, biology and chemistry and inputted these factors into a grand quantitative model they had designed. Their results support the theory that RNA polymers formed in small, warm ponds of water. Meteorites contributed to this process by transferring enough organic molecules to these pools to ensure that RNA started self-replicating in at least one pool.

What's more, the team discovered that, according to their calculations, life may have have begun on Earth rather early. The process may have started just a few hundred million years after the planet cooled sufficiently to support liquid surface water. The results were published in Proceedings of the National Academy of Sciences.

This quantitative model is important because it's the first time anyone has taken all these variables and run this kind of mathematical calculation. "Because there are so many inputs from so many different fields, it's kind of amazing that it all hangs together," said Ralph Pudritz, the paper's co-author. "Each step led very naturally to the next. To have them all lead to a clear picture in the end is saying there's something right about this." Understanding these processes and how life evolved on Earth is not just crucial to our own understanding of how we got here, but it's important to our search for life on other planets as well.

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