What is life?

The question has confounded human beings since we have been around. We can accept that golden retrievers, oak trees, and bacteria are alive, but when we start talking about origins, “alive” becomes a tricky term. Attempting to define life, we often look for the cutoff point – the moment 3.7 billion years ago when non-life ended and life began, when a batch of self-replicating molecules became a microorganism, when chemistry became biology.

In 1952, scientists Stanley Miller and Harold Urey attempted to recreate this moment. They crafted a chemical cocktail to mimic the elemental composition of our planet’s primordial seas, and they submitted this mixture to an electrical charge. They waited and watched, and found that their experiment produced the same amino acids that serve as the building blocks for all life on Earth. However, although the Miller-Urey experiment created amino acids, it did not generate life.

In a recent paper in the Journal of the Royal Society Interface, scientists Sara Imari Walker and Paul C.W. Davies argue that Miller and Urey might have been looking for life in the wrong places. By confining the search for life’s origins to the realm of chemistry, as Miller and Urey did, we make the mistake of ignoring the critical role of information. Walker and Davies argue that the capacity for information processing and storage might be the defining property of life on Earth. In living beings, information flows in two directions – we receive information from our environment, and we actively respond to that information.

You can throw flour, sugar, and eggs in an oven, but you won’t get a cake. Life is more than the lucky product of a stew of elements; biology is more than complex chemistry. The chemical ingredients for life were replicating in that primordial stew, but abiotic self-replication (like we see in viruses) is completely passive. Biological self-replication (like we see in bacteria), on the other hand, is the result of active information control. According to Walker and Davies, the origins of life lie in that information.

Read more at LiveScience.com

Find the original article in the Journal of the Royal Society Interface

Published On: December 21, 2012


  • Roy Niles says:

    The rest of the article says that “when a person touches a hot stove, the molecules in his hand sense heat, transmit that information to the brain, and the brain then tells the molecules of the hand to move.”
    And says “By contrast, if you put a cookie on the stove, the heat may burn the cookie, but the treat won’t do anything to respond.”
    Why not point out then that life uses information to make choices and cookies don’t.  Because when the heat is on the cookie, it does react by burning.  The difference is it has no other choice, while the body with the hand can choose of it must to let it burn.
    What life forms do is use proactive choice making intelligence.  Does anything else in the universe do that?
    We don’t know.  Except that cookies and the like apparently cannot.

  • Zachary Velcoff says:

    You bring up a good point, Roy, and one which leads us to the question of autonomy.

    If everything a particular organism (in this scenario we’d probably be talking about certain forms of unicellular life) does is involuntary, i.e. if there is no element of choice in the (re)actions of this organism, can we still use proactive choice as our yardstick for delineating life?

  • Roy Niles says:

    Zachary, if the organism is able to function proactively at all, then to that extent it’s alive.  We all have non-choice reactive elements in our constructions, such as our hair, which has no choice except to grow, along with nails, horns, etc.  But they grow because we’ve made the choice to find and make use of the energy and earth’s chemicals to devise and build these countless components of our forms.

  • Zachary Velcoff says:

    I’m curious whether exceptions to this rule exist, organisms whose processes are entirely involuntary and reactive. Take sessile autotrophic bacteria, for instance – can we say that they make choices, that they function proactively?

  • Roy Niles says:

    All bacteria colonize, and all have ways to probe their environment and communicate with others in the colony as to what they find and learn (how many or how distant are those others I don’t pretend to know).  All of this involves choices made both by the individuals and by acceptance of the choices made by or through the preponderance of others.  The fact that bacteria have an element of “cheaters” in all known strains should demonstrate they can refuse to agree, for example.
    Bacteria engage in quorum sensing as another example, although I can’t be certain that they all do.  In an case its clear from all the things that bacteria have found ways to do that they make choices that in many ways exceed our human capacities to do the various things that they routinely choose to.

  • Roy Niles says:

    I have to add that I’m not a scientist, I’m just a sort of autodidact who studies and tries to write on such things as the motivating factors of biological functions and behaviors.

  • Roy Niles says:

    I wrote a short book that mentions this type of cheating, although my argument was that this is usually a form of the deception which all forms of life engage in.  You can google some papers and articles by biological scientists such as James A. Shapiro and Eshel Ben Jacob, who know much more about the subject than I do.

  • Zachary Velcoff says:

    Thank you for sharing your knowledge! If you have info or links about bacteria cheating and refusing, I’d love to read more; it sounds fascinating.

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