Sunday, August 23, 2015

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.


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]

23 comments :

  1. This looks like a good opportunity to ask this question again. A while back I posted this in a different post, but it was completely off topic, so maybe now someone with the expertise can shed some light on this.

    It's about the discovery of organic molecules in the comet 67P by the Rosetta:

    http://www.nytimes.com/2015/07/31/science/space/rosettas-philae-lander-discovers-a-comets-organic-molecules.html?_r=0

    Does this discovery bear any relevance to biologists? Could it be an indication that life in other planets is more plausible than before?

    I take it from this post and PZ Myers' that it probably has no connection with the origin of life here in the earth, but how about other places?

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    1. I think it just means that organic molecules can form fairly easily in diverse environments. That would have to be true for live to evolve anywhere, of course, but it's just a necessary background fact.

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    2. As an astrophysics student, I would also like to see this question addressed. Along with comets, as mentioned by Dazz, organic molecules have also been found in interstellar media. But does this matter much to origin of life research?

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  2. This is a welcome blog. There seems to be a marked lack of peer review of anything to do with the primordial soup. Organic chemicals in space and in the primordial earth are treated as a spectacular contribution to OOL studies - but this research has got nowhere since Miller's experiment. The Metabolism First hypothesis is interesting, but does it address the origin of biological information?

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    1. What do you mean by "biological information"?

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    2. Are you the David Tyler of the Biblical Creation Society?

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    3. There's a David Tyler listed in this group, as well. Not that it's that uncommon a name, of course.

      http://origins.swau.edu/

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    4. I can spot a creationist a mile away by now, they all say the same shit

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  3. The amount of amino acids from space is far less than you expect. More than half of the annual flux you mentioned is by micrometeorites. Typically, micrometeorites have spherical shape formed through the complete melting during atmospheric entry. Thus, they do not contain labile organic compounds like amino acids and nucleobases.

    The concentration of amino acids in cosmic dusts are not determined. In the latest work, the NASA Goddard team analyzed several interplanetary dust particles (IDPs). But they could not determine the concentration because the concentration was comparable to terrestrial contamination. If we expect that the concentration of amino acids in IDPs are comparable to carbonaceous chondrite, that should have wide concentration range. The most famous carbonaceous chondrite, Murchison meteorite, contains 0.0015% amino acids including non-proteinogenic amino acids. And most of other meteorites contain less amino acids.

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    1. Really interesting stuff, thanks rhaeyga. Does that mean that the aminoacids found in those carbonaceous chondrites could just be contamination too?

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    2. No, carbonaceous chondrites contain amino acids. Such amino acids have different carbon and hydrogen isotope ratios from terrestrial amino acids.

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  4. Life is more than chemistry. This quote develops the point:
    “In the face of the universal tendency for order to be lost, the complex organization of the living organism can be maintained only if work – involving the expenditure of energy – is performed to conserve the order. The organism is constantly adjusting, repairing, replacing, and this requires energy. But the preservation of the complex, improbable organization of the living creature needs more than energy for the work. It calls for information or instructions on how the energy should be expended to maintain the improbable organization. The idea of information necessary for the maintenance and, as we shall see, creation of living systems is of great utility in approaching the biological problems of reproduction.” George Gaylord Simpson and William S. Beck, Life: An Introduction to Biology, 2nd ed. (1965), 145.

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    1. That doesn't support your conjecture that "life is more than chemistry." That "information" can be, and is, encoded in chemical structures.

      Cards on the table, if you will: Are you a creationist? Are you trying to lead to a conclusion that this "information" could only have been created by God or some other "intelligent designer"?

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    2. I'm happy to let people make a judgement on whether the quotation supports the statement "life is more than chemistry".
      My posting was intended to commend Larry Moran for his clarity on the primordial soup issue, and I do not want discussion to detract from that.

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    3. So no answer to my question? I wonder why.

      If you don't want to distract from Larry Moran's clarity on the issue, the I fail to see why you would want to pollute this discussion with this nonsense about "information."

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    4. 1. Because the information takes the form of the sequence of nucleotide bases in DNA, the distinction between information and chemistry in this case is moot.

      2. This introduction was apparently written unclearly enough that it could be interpreted as saying that information is separate from chemistry in this case, if you didn't know about #1.

      3. What a 1965 intro to biology textbook said has no particular authority or even interest, except as an example of the history of biology instruction.

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    5. ....or as a source of creationist quotemines. Don't forget that.

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    6. Tyler, it doesn't matter what you or anyone else think that quote mine is meant to say. It's what the authors meant what matters and that's obviously not what they meant. That dishonesty is the hallmark of creationism and you're obviously one.

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    7. I don't know Dazz. If I squint at the screen just right, when I read that passage I think I can make out the word "Goddidit."

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    8. Truth is anything that contains the words "complex", "improbable" and "information" in the same paragraph exhibits all the symptoms of creatarditis, but apparently that book also treats evolution as a scientific fact. Is Taylor going to subscribe that too?

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    9. I think Larry would be well advised to be wary of this David Tyler misquoting this post as supporting the claim that naturalistic abiogenesis is impossible.

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  5. Unfortunately primordial soup was espoused not only by Oparin, but also by J. B. S. Haldane, who should have known better, but probably didn't think through the implications of the huge dilution factor. As we know, people tend to accept the views of great men more easily than those of unknowns. To be honest, it was only while listening to a lecture by Bill Martin that I realized that primordial soup was a non-starter. Until then I hadn't really thought about it, but I should have, as I went to a lecture by Oparin many years ago (probably in 1966).

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