Comets and meteorites CAN NOT create a primordial soup in the ocean

I want to talk about two recent press releases on the origin of life.

The first one is from the BBC and it talks about the work of Haruna Sugahara and Koicha Mimura who presented their results at a recent conference [Comet impacts cook up 'soup of life']. They noted that the impact of a comet carrying organic molecules can produce more complex organic molecules.

The second report is from ScienceDaily. It reports a similar study by Furukawa et al. (2015) who examined the idea that the impact of meteorites in the primitive ocean could create more complex organic molecules than those already found in meteors [Meteorite impacts can create DNA building blocks].

A new study shown that meteorite impacts on ancient oceans may have created nucleobases and amino acids. Researchers from Tohoku University, National Institute for Materials Science and Hiroshima University discovered this after conducting impact experiments simulating a meteorite hitting an ancient ocean.

With precise analysis of the products recovered after impacts, the team found the formation of nucleobases and amino acids from inorganic compounds. The research is reported this week in the journal Earth and Planetary Science Letters.

Both stories assume that life began in a primitive ocean full of amino acids, sugars, and bases. The problem, they assume, is proving that comets and meteorites could deliver such molecules to Earth. That's why these experiments are important.

I've blogged about this several times: More Prebiotic Soup Nonsense, Can watery asteroids explain why life is 'left-handed'?, Simulated meteorite impact produces RNA bases. So what?, and NASA Confusion About the Origin of Life: Part II. The main problem with this scenario is that the maximum concentration of organic molecules could only be about 0.1 nM (10^-10 M).

This is nowhere near high enough to drive the formation of polymers such as peptides and nucleic acids. The idea that comets, asteroids, and meteorites could deliver enough organic molecules to create a reasonable primordial soup is absurd. No respectable biochemist believes such a scenario.

The only reasonable scenario is one where simple organic molecules are made directly from compounds such as methane and acetate in a local environment. This is the Metabolism First hypothesis [Metabolism first and the origin of life].

I wish scientists and science journalists would stop treating the primordial soup idea as the leading candidate for the origin of life. It would be a ridiculous idea even if there were no better explanations but it's even more ridiculous when a much better idea is out there. All you have to do is a bit of research or read a book.

At the very least, all scientists who postulate an oceanic primordial soup should be required to discuss the concentration problem in their papers and give references to experiments indicating that the ocean could contain sufficient concentrations of organic molecules to drive abiogenesis. They should also be required to demonstrate that they are aware of alternative hypotheses (e.g. Metabolism First) and explain why their scenario is better.

UPDATE: PZ Myers has a similar take on this issue: We Now Know For Sure How Life Did Not Begin on Earth.

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Furukawa Y., Nakazawa H., Sekine T., Kobayashi T., and Kakegawa T. (2015) Nucleobases and amino acids formation through impacts of meteorites on the early ocean. Earth and Planetary Science Letters, [doi: 10.1016/j.epsl.2015.07.049]