Sunday, April 05, 2015

198.8 - And Another Thing: new research suggests way life began

And Another Thing: new research suggests way life began

One of the most common misunderstandings about evolution is found in the charge - intended as a withering attack - that it can't explain how life began.

That's true - it can't. It's also wholly irrelevant because that's not what evolution in about. Evolution is about how life changes in response to, and in turn affects, environment. The question of how life began is an entirely different field of study called abiogenesis (or biopoiesis).

The problem for abiogenesis is that the origin of life on Earth looks like a string of conundrums. There has to be something like DNA or RNA to make proteins but modern cells can’t copy DNA and RNA without the help of those very proteins. And none of these molecules can do their jobs without fatty lipids, which provide the membranes that cells need to hold their contents inside - but the protein-based enzymes encoded by the DNA or RNA are needed to synthesize lipids.

That is, everything needed for the thing it is responsible for creating to have already existed in order for that first thing to be there to make it. It's the old chicken-and-egg question.*

Now, a team of researchers at Cambridge University in the United Kingdom have found that just two simple compounds, hydrogen cyanide (HCN) and hydrogen sulfide (H2S), each of which would have been abundant on the early Earth, plus ultraviolet light, also abundant on the early Earth, can initiate a series of chemical reactions that produce all three major types of biomolecules - nucleic acids, amino acids, and lipids.

These are separate sets of reactions; it's not one reaction producing all three at once in the same place. The important point is that these reactions provide an independent means of producing these types of molecules, breaking out of the chicken-and-egg trap by providing a point of entry into the now-existing pattern.

This work, published in the peer-reviewed journal "Nature Chemistry," does not prove this is how life started but it does provide at the very least a plausible mechanism by which it could have happened, a mechanism that is in line with current best knowledge about the chemistry and conditions of the early Earth.

Which I think is pretty doggone cool.

*Which does have an answer, by the way.

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