National Geographic

How Did Life Begin? It’s Not About the Planets So Much As the Chemistry

At the end of August, I got a press release saying that a chemist named Steven Benner was going to deliver a lecture in Italy in which he broached the idea that we might descend from Martians.

I met Benner ten years ago. He was sitting in a coffee shop in Cambridge, Massachusetts, working out what it would take to make life from scratch. Helping him in this exercise was Jack Szostak, a Nobel-prize winning Harvard biochemist whom he had known for years. In the midst of their conversation, Dr. Benner abruptly turned to me and asked, “How much do you think it would cost to create a self-replicating organism capable of Darwinian evolution?”

As a journalist, I’m not accustomed to such questions. “Twenty million dollars?” I blurted.

“Ridiculous,” I thought to myself. But Benner just tilted his head, looked away, and nodded in thought.

“That’s what Jack says,” he said.

Benner, a distinguished fellow at the Westheimer Institute at the Foundation for Applied Molecular Evolution in Florida, has balanced his career between two ways of doing science. On the one hand, he is a data-driven chemist who publishes papers with heart-stopping titles like, “Labeled nucleoside triphosphates with reversibly terminating aminoalkoxyl groups.” On the other hand, he is the sort of scientist who enjoys trying to draw up Frankenstein’s budget, or investigating whether life could exist in the liquid methane oceans of Saturn’s moon Titan.

So I knew that he’d have something interesting to say in his talk about Mars.

Not surprisingly, many reports have gone for the Little-Green-Men angle. But when I caught up with Benner, we ended up talking not about alien life, but about the philosophy of science–about how to investigate the origin of life when it happened so long ago and we still have so much left to learn about it. That conversation is the subject of my new “Matter” column for the New York Times. Check it out.

There are 6 Comments. Add Yours.

  1. Torbjörn Larsson, OM
    September 16, 2013

    Thank you! A much more interesting description of Benner’s proposal. (Which I hope gets published.)

    I think all his 3 main assumptions (environment, borate need, oxidized molybdene lack) are arguable. But the main problem is the environment.

    – The scenario predicts as constraints that Earth was water covered and Mars had little water. Both these constraints seems less likely, and the first is pretty much rejected by observation.

    Earth likely had a weathering (continental) crust before ~ 4 Ga bp, when life likely arose. Ushikubo et al 2008, “Lithium in Jack Hills zircons: Evidence for extensive weathering of Earth’s earliest crust”. [ http://www.geology.wisc.edu/~wiscsims/pdfs/Ushikubo_EPSL2008.pdf ]

    Early Mars had as much mantle water as Earth has. If the bulk of terrestrial water comes from accreation (as seems consistent with Earth, Moon and Mars D/H isotope ratios), or if the water content had equilibrated, early Mars could have been as ocean covered as early Earth.

    [ http://www.dailymail.co.uk/sciencetech/article-2163252/Even-water-solar-Marss-mantle-contains-water-Earth.html ]

    – Relying on oxygen means having an environment where sources produces much less organics, by a factor of ~ 1000. The concentration of organics is already a problem.

    Arguably there are other problems with Mars. It may be that the only clement conditions for global habitability were ~ 3.8 – 3.6 Gap bp, when the Tharsis volcanoes temporarily thickened the atmosphere. [ http://www.planetary.org/blogs/emily-lakdawalla/2013/what-mars-valley-networks.html ]

    This should be contrasted with recent claims of microanalysis of Isua BIFs that predicts Fe reducers despite the metamorphosed state of the rocks, complementing earlier claims. This may push earliest life on Earth from ~ 3.5 Ga bp today to ~ 3.8 Ga bp.

    Such a timetable squeezes Mars from two directions. If it had time to develop life, maybe Earth was first. Ironically then it may be likeliest Earth seeded Mars if anything.

    [FWIW, I prefer the stabilization pathway that selects the components of RNA above other sugars and nucleotides. These components are stabilized by protocell lipids and in turn stabilizes the membranes. "Nucleobases bind to and stabilize aggregates of a prebiotic amphiphile, providing a viable mechanism for the emergence of protocells", Black et al, PNAS 2013.

    Until Benner's scenario is put on paper I don't know how much such a pathway supplants his requirements. But preselected components are shorter, likelier pathways in both pure and dirty (ce-evolving) RNA worlds.]

  2. Muneera Alotaibi
    September 19, 2013

    Thank You!!

    Life Came From Water
    God “made from water every living thing” also “God has created every animal from water. Of them are some that creep on their bellies, some that walk on two legs, and some that walk on four. God creates what He wills, for truly God has power over all things”. These verses support the scientific theory that life began in the Earth’s oceans.

  3. John Jay Pelletier
    September 24, 2013

    God had nothing to do with Life–It’s Mother Nature.

  4. David Bump
    September 24, 2013

    Of course, there’s still the non-scientific belief that God created life fully functioning, supported by the fact that we still haven’t figured out how raw chemicals alone could form anything with dynamic organized complexity, let alone true self-replication. Perhaps someday we will figure out how it could happen; if not, we might eventually learn to appreciate just what an amazing feat it is to make something like a bacterium. Is part of being made in the image of God the potential to create such a thing? And if we achieve it, will we be like precocious children making an atom bomb without fully understanding it?

  5. Daniel Bastian
    February 26, 2014

    Sigh. It’s as if any story about the origin of life is an open invitation for religious devotees to share their “God” hypothesis and bloviate on which holy verses corroborate which scientific finding.

    OT: Personally, I’m interested in what really happened, about how life really got started. As Brenner and Zimmer discuss, if terrestrial life originated from Mars, it would simply regress the origin of life one step back into the past. But if a Martian origin is right, it would push us in the right direction. Great piece, as always!

    • David Bump
      February 26, 2014

      You needn’t resort to put-down terms like “bloviate” and talk about what “really” happened in an area that has not yet been demonstrated to be explainable in purely scientific terms, and in fact is exactly the opposite of the course of nature observed countless times for millennia — anything short of a functioning living organism tends to break down over time, not become more complex and life-like. Scientific investigation can do many wonderful things for us, but it should not become a box into which all our thinking about everything throughout all time and space must be made to fit. There is no telling what things that really happened we might miss or misunderstand if we start by making up our minds to make one explanation fit all.

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