Cometary Impacts May Have Provided Key Elements of Life

trendspotter writes with news of research indicating that impact events might be responsible for seeding the Earth with reactive forms of the precursors to amino acids. From the article: "Early Earth was not very hospitable when it came to jump starting life. In fact, new research shows that life on Earth may have come from out of this world. Lawrence Livermore scientist Nir Goldman and University of Ontario Institute of Technology colleague Isaac Tamblyn (a former LLNL postdoc) found that icy comets that crashed into Earth millions of years ago could have produced life building organic compounds, including the building blocks of proteins and nucleobases pairs of DNA and RNA. Comets contain a variety of simple molecules, such as water, ammonia, methanol and carbon dioxide, and an impact event with a planetary surface would provide an abundant supply of energy to drive chemical reactions." The paper (PDF).

Comments

Re:In laymans terms (since I'm a layman)

[Samantha Wright]

You'll have to narrow your scope a little: we're pretty sure that all of the interesting bits of evolution (the distinction between bacteria and archaea, the rise of animals, plants, protists, and fungi, multicellularity, and everything since) happened right here. To use a surprisingly good computing analogy, not only do we have the fossil records, but we can compare the source code and see where the forks happened. A lot of the most interesting adaptations are serendipitous re-uses of really old code.

The possibility that living cells might have arrived on Earth is considered something of a toss-up. There have been quite a lot of difficult-to-test proposals about how they could've arisen from fairly basic building blocks here, and they all seem pretty plausible. We're pretty sure about the RNA world hypothesis (the idea that life only started using proteins for enzymes and DNA for storage later, and started off using just what we think of as a makeshift intermediary for everything) but we don't have much of a clue about what happened before that, and we can't say for certain it happened here or not. We also don't know how life went from being a single self-replicating molecule into a membrane-protected cell, nor if there was some storage molecule before RNA that was even simpler to operate on.

However, this article is almost certainly wrong because RNA's inherent stability causes it to evolve at a much faster rate. So at the very least, it's still possible that there was enough time for life to evolve here from pure abiogenesis.