79 | Sara Imari Walker on Information and the Origin of Life

/ Biology, Chemistry, Complexity / 18 Comments

We are all alive, but "life" is something we struggle to understand. How do we distinguish a "living organism" from an emergent dynamical system like a hurricane, or a resource-consuming chemical reaction like a forest fire, or an information-processing system like a laptop computer? There is probably no one crisp set of criteria that delineates life from non-life, but it's worth the exercise to think about what we really mean, especially as the quest to find life outside the confines of the Earth picks up steam. Sara Imari Walker planned to become a cosmologist before shifting her focus to astrobiology, and is now a leading researcher on the origin and nature of life. We talk about what life is and how to find it, with a special focus on the role played by information and computation in living beings.

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Sara Imari Walker received her Ph.D. in physics from Dartmouth college. She is currently Associate Professor in the School of Earth and Space Exploration at Arizona State University, Deputy Director of the Beyond Center for Fundamental Concepts in Science, and Associate Director of the ASU-Santa Fe Institute Center for Biosocial Complex Systems. She is the co-founder of the astrobiology social network SAGANet, and serves on the Board of Directors for Blue Marble Space.

18 thoughts on “79 | Sara Imari Walker on Information and the Origin of Life”

  1. Mike Lensi

    Best podcast episode of 2020! (Low bar I know, but I did at least listen to the Dennett episode 😉
    1) Dr Walker’s idea that there is “missing physics” in the form of an information-type theory is something that I’ve heard Carlo Rovelli also say, although his field is quantum gravity / thermodynamics; very interesting.
    2) I wonder if Dr Walker has betrayed the fact that she leans more toward “weak” emergence when she says that artificial satellites stem from “some kind of intelligent process with knowledge of the laws of gravitation and engineering principles”, because those laws themselves produced our natural satellite, which preceded our artificial ones.
    3) I also love the idea of life as a planetary process, and I wonder if maybe the simplest definition of life might be “an emergent entropy pump”, and by emergent I mean it would be cheating to go backwards in complexity such that less-complex entropy pumps created by more complex pumps would violate the definition.
    So fun! Cheers all!!

  2. Michael Lensi

    Oooh:
    4) I also love the discussion on meaning vs information (e.g. when Dr Walker says “a semantic representation or some kind of symbolic way of describing things that both the sender and receiver understand”). I tend to think of meaning as a relativistic form of information. Again, so fun!!

  4. L

    A minor correction to the transcript at 00:57:47 – the paper Sean refers to is by Mark Bedau, not Marc Vidal. It’s available in full on Bedau’s site http://www.reed.edu/~mab if anyone’s interested in further reading. Quite an interesting topic which comes up in a few podcasts (e.g. the David Chalmers episode), so worth a look.

  6. Brian

    Please consider summarizing your guests’ main ideas, and perhaps reflecting on the implications of these ideas, at the end of each podcast.

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  8. Lyle Murphy (AKA Frank LaCroix)

    Very good podcast! I would recommend that Dr. (?) Sara Walker lay off the caffeine – the rate at which she speaks is off the Richter scale. No biggy. I just listen again, pause the mp3 and catch up and ponder the ideas.

    Loved it!

  9. Jackie

    I loved this episode!

    The question of whether some notion of “life” can refer to abstract things like societies and processes, in addition to the individual biological units that create those things, is so interesting (and makes so much sense, as all of us are made of smaller biological units working together to create an abstract thing, and WE count as life). Could a person inside a car be thought of as its own form of life, with the person as the brain/nucleus/control center? Is a house people are living in its own quasi-alive thing, as a structure with organized insides, a regulated internal temperature, and different processes and routines like dishes and laundry that are carried out by agents inside of it? A house can’t reason or have goals, it’s true, but it’s surely still meaningful to consider that when you try to design the perfect place for a living thing to live, you end up with something that has so many parallels to life itself (internal organization, processes, etc.), completely unintentionally. Is a highway a kind of abstract bloodstream that supplies material to buildings, as they carry on with their internal processes? If all of the dishes in a house break, new dishes are needed for the dishes-process to continue. I wonder if it’s meaningful that life can often create structures that “look like” itself in terms of being organized and having processes in a life-like way, which then in turn do the same thing (a cell is internally organized and has processes, it contributes to a person that’s internally organized and has processes, a person contributes to a house that’s internally organized and has processes, the house contributes to a country that’s internally organized and has processes, etc.). Electrons and protons and such are distinctly not alive, and they will happily build structures all day that have no obvious “signature” that points to the structure being made out of packets of charge and so on. Maybe quantum mechanics can be so “spooky” to people precisely because we’re so conditioned to understand complex structures made by living things that when the telltale signs aren’t there, whether we know we’re looking for telltale signs or not, we do know that we’re out of our element.

    On the subject of planets and moons and such being alive, I think it’s really cool to consider that Earth as a planet has an outer membrane, a fluid inside that’s warmer than its environment, and something that sure is shaped like an inner nucleus. Volcanoes could be a way to expel waste products. Have we ever looked for organelles inside Earth? Do we know that it’s NOT a big single-celled organism? We have gut bacteria and things living on our skin, it’s not uncommon at all for life to provide shelter for other life. I wonder if we’ll ever find magma whales or some kind of symbiotic critter that lives inside the earth. Maybe this line of thinking isn’t useful for considering how the world works, but I’d happily read a cool science fiction story about a planet that did work like that.

  10. Vanessa

    By far one of my favorite episodes of yours! Listening to her speak incites a flurry of cross-disciplinary ideas in my head.

    Also, it should be Stuart Kauffman*, instead of Stewart Copen.

    Cheers!

  12. Joel McKinnon

    My favorite idea was the concept of biospheres reproducing by generating sufficiently advanced beings to develop the ability to migrate beyond the biosphere and alter other planets to allow their own form of life to exist on the surface. It makes the idea of terraforming other worlds, such as Mars, feel less of an extreme option, rather one that is essentially an inevitable result of a fully mature biosphere.

  13. Joel McKinnon

    In Planet and Sky, my rock opera and podcast, the “Sky” character serves as the voice and intelligence of a biosphere married to “Planet” who serves as the body and, to some extent soul of the union. There is an implicit tragedy due to the inability of the union to be sustained long enough to permit an advanced species to evolve and emigrate off world. What I failed to consider is why they (Planet and Sky) should care. Parker’s idea makes it clear. They are “dying” before they can reproduce! If interested please have a listen to the podcast/album at planetandsky.com and please let me know what you think.

  15. Jayarava

    I found this very stimulating and informative (which I seldom say about people talking about origin of life). I thought Sara had an amazingly open attitude and willingness to say “I don’t know” (words we don’t often hear from male scientists).

    Some great perspectives here.

    To my mind the fundamental problem with RNA world and replication first models is *feedstock*. Nucleotides don’t just spontaneously form from random environmental bucket chemistry. It takes several specific chemical pathways to produce a sugar and an amino-acid and a phosphate anion, and they don’t easily co-exist. And to get sustained replication you need a constant feedstock of building blocks. RNA seems like a phase life might have gone through, but only in an environment that churn out building block molecules and turn them into nucleotides. That environment is *metabolism*.

    The idea that planetary scale processes define life rather than individuals is intriguing. The downside of the liberal ideology (whether classical or social or neoclassical) is that it too easily falls prey to sophistry – it sees the individual in isolation. Sean used to have a Twitter bio that read “If the blind guys had just compared notes they have quickly figured out it was a elephant.” Science is a social activity. All humans are social (with very few exceptions). Sociality defines our psychology not the other way around.

    The idea that bacteria exchanging genetic material between cells and across communities is familiar from Lynn Margulis, who sometimes made the point that since all bacteria can, in principle exchange bacteria with all other bacteria they are all one species. A bit surprised to find that gene transfer is not considered Darwinian evolution though. Natural selection is still at work. Isn’t it?

    And finally Sara’s argument for strong emergence was a humdinger – the standard model was written down by humans. Maths and physics emerged from human minds: “physics is an emergent property of biology”. Hell yes!

    So it seems that we might have to invert the hierarchy of sciences a la Comte and Mill: biology > sociology > psychology > mathematics > physics & chemistry.

  16. dmf

    Sara notes the messiness/uncertainties of non-math grammatical/symbol exchanges but includes social assemblies in her theorizing, what is it that binds them together and isn’t our uses of maths achieved via non-math communications/socialization?
    “In The Social Theory of Practices as well as in other writings Turner argues against collective concepts like culture: what we call culture (and similar concepts), he argues, needs to be understood in terms of the means of its transmission. There is no collective server by which it is simply downloaded and “shared”. What we take as “collective” is really produced through experiences of interaction which are different and produce different results for different individuals but which also produce a rough uniformity through mechanisms of feedback rather than “sharing”.”

    https://en.wikipedia.org/wiki/Stephen_Park_Turner

  17. Tom McDonald

    Fascinating! But since I struggled with being out of my depth, I wonder if anyone here could suggest a layperson’s book (or a lecture series, etc) on the topics and questions explored in this episode, I’d appreciate it, and perhaps others would too. In the meantime I’ll explore the guest’s other talks and resources, and get a better grip on some biology basics. Thanks.

  18. Peter Smoyer

    Your most captivating and though provoking episode. Physics, Chemistry, Philosophy. All in one place. And you did an excellent job keeping her on track and guiding her through this diversity.

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