Plant Based Collective Cognition (artwork by Ricard Solé)
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Heather: You know, other worlds that we see in our solar system, other worlds that may exist within our own planet, other worlds we're only just now beginning to understand that can be capable throughout the universe. 


Abha Eli Phoboo: From the Santa Fe Institute, this is Complexity

Chris Kempes: I’m Chris Kempes.

Abha: And I’m Abha Eli Phoboo.


Chris: For our final episode this season, we’re going to learn from a fellow astrobiologist whose expertise spans from the deep, untouched regions of our planet all the way to organic chemistry happening in space.

Heather Graham: I'm putting on my glasses now so I feel smarter.

Chris: This is Heather Graham. Heather by the way, uses both they and she for gender pronouns. In this episode, you’ll hear us use “they” and “them.” 

Abha: Later in the episode, I’ll also sit down with Chris and hear more of his perspective on what we’ve covered this season. But first, Heather. And we’re not sure that they really need those glasses to seem smart.

Heather: Yeah, so my name is Heather Graham. I'm a research physical scientist at NASA Goddard Space Flight Center, and I work on biosignature definitions and biosignature strategy. Well, maybe I shouldn't say strategy. That's such a loaded term anymore. But biosignature definition for the purpose of in situ instrumentation design and spaceflight experiments.

Abha: And Heather’s talents aren’t just limited to biosignature definition and spaceflight experiments. 

Heather Graham: Yeah, yeah, yeah. So I wrote an opera, a short opera about Katherine Johnson. 

Chris: You might remember Katherine Johnson from the movie — or the book — Hidden Figures. It told the story of three Black women at NASA — Katherine Johnson, Dorothy Vaughan, and Mary Jackson — who were the brains behind one of the most important operations in the U.S./Soviet Space Race. Heather’s rock opera about Johnson was performed in 2015, a year before the Hidden Figures book or movie was released.

Heather: And it was staged three times, twice in Baltimore, once in Boston. And it moves back and forward in time through her life story. So all of her dialogue is taken from interviews with her. 


Katherine Johnson: I’ve always liked numbers. Math — not just any kind of math, but math that means something, math that takes you somewhere.

Heather: And there are puppets involved. The puppets are the Apollo astronauts and all of their dialogue was taken from transcripts. And it's a piece of work I'm really proud of since I think it kind of got really into the nature of discovery and the nature of struggle in discovery, because I was trying to represent her struggle to be seen as an expert in her field. 


Man: Excuse me! We’re having a meeting here.

Katherine Johnson: Well I know that. But I’ve been doing all the math on this, I figure I should know exactly what’s happening.

Man: You all don’t normally go to these meetings

Heather: And the discoveries that she made during her tenure at NASA and how really a lot of that became how we are able to do space travel today. 


Katherine Johnson: I don’t know if people will remember who we are if we do a good job. But if we fail, we’ll be remembered for sure and it won’t be a good memory.


Abha: Heather’s interested in what they describe as understanding other worlds.

Heather: You know, other worlds that we see in our solar system, other worlds that may exist within our own planet, other worlds we're only just now beginning to understand that can be capable throughout the universe. 

Chris: Even though Heather works at NASA and, like me, is interested in what can be discovered out in the universe, much of their work has actually been examining our own planet Earth.

Heather: When you think about astrobiology, you're trying to understand similar origin points. 

Abha: So, searching for insights about life that can be applied across the entire universe. 

Heather: And when we look at it through earth history and paleontology and paleobiology, we're starting with where we're at now and moving back in time and trying to understand all of these hidden events that led to where we are right now with life, that led to this plethora of organisms that are around us. And I think if you go farther back and back and back in time, pretty soon you're in this region that is general enough, you can start to think of it in ways that aren't applicable to this planet. You're starting to think about life in more general terms as it may be related to life that could be anywhere. I think something that's really part of that is understanding that Earth hasn't just been this world we see around us. Earth has been many planets. Earth has looked many different ways and some of the Earth's that we see in the past which are wildly different than the way Earth looks like now are more similar to some of the other worlds that we see in our solar system and may exist outside of our solar system. And so you can use Earth history as this sort of experimental test bed for thinking about life elsewhere in the universe as well.

Abha: In our last episode, David Krakauer brought up the idea that life, traditionally speaking, is not a comparative science. We only have one origin of life to look at.

Chris Kempes: And people often point to that as a central problem in astrobiology. But what you're saying is that that's not true. The history of earth gives us many examples of planets with examples of life and the diversity of life gives us many examples of life. So are you sort of against the N equals one problem that people say in astrobiology?

Heather: Well, I think one fundamental problem I have with that idea of the N equals one, it's true that all of the organisms that we are examining in labs and that are similar to us, we all have a common heritage. But we don't know if life has arisen in other forms in other places on our planet and just simply not persisted. 

Chris: It’s worth saying that again. We don’t know if life has arisen in other forms in other places on our  planet and simply not persisted. And Heather’s not talking about an abstract re-imagining, like if culture is alive or ideas are alive. We’re talking about cells and DNA and proteins here.

Abha: The question they’re asking feels, somehow, both obvious and totally radical. Why would we assume that our own tree of life is the only one that’s ever been here?

Heather: I think that… that is something that's very astrobiologically relevant. The idea of multiple origins, and this is just the current expression we have that's dominant on our planet right now. And also the idea that possibly there could be other organisms that are sufficiently different from us, that it's very hard for us to even understand and experiment and examine that kind of life because it's so different from us, because our search pattern is so trained on what our own biology is. So I think that's one way in which I would fundamentally kind of push back on the N equals one idea.

Abha: One area that could hold another origin of life is the deep subsurface of the Earth’s crust. 

Heather: I do work in caves, but also I look at life that may be possible in the deeper regions of the Earth There's parts of the deep subsurface of the Earth that have been out of communication with the surface of the Earth for a billion or so years. That's enough time that some other type of organism could have been on a completely different evolutionary journey than what we have here on the surface of Earth. And that's worth trying to understand. It's also a great sort of testbed and platform for trying to understand other worlds that are much more energy limited than the Earth is, because in the deep subsurface you don't have that rich chemical energy source that is the Sun. You're reliant on very different sort of primary energy sources when you're in the subsurface, so there’s a couple of different reasons for why I like to look at the environment of the deep subsurface.

Chris: The oldest, interior parts of the continents are called cratons. They’re rocks that are billions of years old.

Heather: This is like in Australia, when we think of beautiful stromatolites that you might have seen, or South Africa is where some of the oldest rocks are. 

Chris: Heather’s worked on the craton in Canada, and underneath this very old thick rock —

Heather: Is water and lots of it. And it's in fracture systems inside this very old rock. And we can tell from the gases inside this water that it has not been influenced by the meteoric water system, the surface water system of the earth on orders of a billion years. So there's this entire, you know, you could think of it as a very diffuse interior ocean inside the continents that has been separated from the oceans of the surface and the ocean of life on the surface for a billion years. You know, if you've got water and you've got some sort of energy source, is there the possibility for life there? 

Chris: So it's like an aquarium that got sealed off a billion years ago and buried, is what you're saying.

Heather: Oh, I love that. Yeah. 

Abha: Okay. I have an idiot question actually. So has anybody had the chance to drink that water? 

Heather: Oh my gosh, you probably wouldn't want to. The water in these systems, the deep subsurface is another great way of understanding the oceans of the solar system because it's incredibly salty, incredibly salty, like five times saltier than ocean water. So it's pretty awful. You could try to drink it, but I don't think you'd like it. [Laughs]

Abha: Okay, if there’s anyone out there who’s thinking this could be some new fancy mineral water to try, consider yourself warned.

Chris: But Heather’s exploration isn’t limited to just old, salty water. Recently, they’ve been analyzing samples from NASA’s OSIRIS-REx mission, the first U.S. mission to collect a sample from an asteroid. In this case, an asteroid named Bennu. 

Heather: And I often find it interesting to think that, you know, people associate space exploration with going out and putting rovers on planets or orbiters around planets or landing on planets and having scientific experiments performed by a robotic system. But sample return is actually an activity that we have been doing as explorers for over half a century at this point. And so it's not just about sending things to other planets, it's about bringing things back as well. And, it's hard to explain just the value in that, unless you can understand just the resolution and precision handling even of these precious samples that you can do in labs here on Earth when compared to what we can do with robotic systems on other planets. So sample return is really a huge part of space exploration, even though all the exploring is happening back in our labs back at home.

Abha: And the reason this is important is that asteroids and meteorites have a lot happening inside them. They produce many of the things we typically associate with life.

Heather: We look to meteorites as being this microcosm of interesting organic chemistry that's happening out in the solar system. And we think of the carbon inside of asteroids and meteorites as representing that store of carbon that came to an early Earth and was all of those first ingredients that would have been mixed up in our oceans that could have become part of prebiotic chemistry. So that's a lot of why we look at asteroids as astrobiologists is to understand if you think of the origin of life as a recipe, meteorites are your ingredient list. It's what's in your pantry. It's what would have been available for all of that early chemistry that could happen on the early earth.

Chris: And while we have plenty of samples from meteorites that have crashed into Earth, they all overheated and burned as they flew through our atmosphere, creating a shell on the outside. 

Heather: And especially if they have a lot of carbon in them, it is very much like an overdone crust, almost coal-like look on the outside of a meteorite.

Chris: We didn’t have any samples that were in a pristine, uncooked condition. Until now.

Heather: Meteorites are full of carbon that they've picked up as they sweep through interstellar space and are picking up those dusty bits and icy particles that are full of organic chemistry all over the solar system. So all of this fluid and chemistry and carbon is doing interesting chemistry on these asteroids. And what's happening is you're seeing a lot of those molecules that we associate with life being generated by the chemistry that's happening in meteorites. You see nucleobases. You see amino acids. You see small molecules that we associate with metabolism. If you look, if you remember back to high school biology and think about those metabolic reaction pathways that you might have had to learn, a lot of those small molecules that are being shuttled around as part of metabolic reaction pathways are present in meteorites as well.

Abha: But the difference between the organic chemistry happening in an asteroid and the organic chemistry happening within something that’s alive, like a human body, is that life has much higher concentrations of these organic molecules than what you would expect from random, spontaneous reactions in the environment.

Heather: Part of that idea is selection. That organisms are selecting what few molecules they really want to focus on building and making lots of them. You end up with some larger, more complex molecule that would have never happened in just the chance chemistry of abiotic systems in space.

Abha: And that larger, complex molecule is interacting with, and a part of, everything around it. Heather echoes the other guests we’ve had on the show, emphasizing how life is really about diverse systems and communities, not individual survival.

Heather: And something I would really challenge people to imagine is that evolution isn't just about organisms. It's about the relationship between those organisms and their environment, what information gets transferred to us, you know, through lineages, has all been driven by what is happening in that organism's environment that made that the right information to be sent on to the next generation. We can look back in time at organisms on some of those very different earlier Earths that I talked about, and it would be very hard to look at those organisms and imagine what they would look like in the future. I always give the example of the Rhynie chert. It's this, the oldest evidence of land plants. It's these rocks in Scotland. And these basically just like look, they almost look like little blades of grass, but they're only a few millimeters big. And they don't really have any roots.

Chris: Heather’s talking about a plant that evolved in the Devonian period, between 408 and 360 million years ago.

Heather: Remember, this is a landscape devoid of life. There was nothing on the surface. The oceans were rich and teeming, but the landscapes were barren. And you look at those little tiny blades of carbon in this very metamorphosed rock, and you would have no way of looking forward in time and seeing redwoods or seeing cactus. So it's always a little bit of a caution to try and predict with evolution because all of the rich plant life that we see now has come through the lens of generations interacting with their environment on the surface of the Earth and all of the trade-offs that had to happen in order for those organisms to send on that information to the next generation about viable structures that will help them continue existence.

Chris: Now I still think we can find laws that bound that diversity and allow us to imagine the future and think about life elsewhere.

Abha: Coming up in Part Two, I sit down with Chris to discuss some of his work, and to reflect on both Heather’s perspective and the season as a whole.


Abha: Part Two: Looking back with Chris


Abha: Chris, you and Heather both describe yourselves as astrobiologists, among other things. Astrobiology is a really broad term --- can you tell us a little bit more about what exactly you mean when you say that?

Chris: Yeah, I actually describe myself as many things and it sort of depends on what group of people I'm in. I call myself an ecologist, a biophysicist, a cell biologist, an astrobiologist. Fundamentally, I'm interested in theories of life and I often call myself amongst friends, a theoretical physical biologist interested in how the same sort of theory can tell us something about modern ecology as well as the search for life in space. 

Abha: What were the questions that brought you to us at the Santa Fe Institute in the first place? 

Chris: So I think in the long arc of my career was as a kid, my first loves were paleontology and astronomy. And I wanted to put those into one thing. And so I would tell people I want to be a paleontologist and an astronomer. In some weird way, that's what astrobiology is. And so then I started discovering and people pointed me to amazing papers that had been done at this kind of institute and biophysics more broadly. And I got really excited about taking what I loved about physics and applying it to these biological problems that I was so passionate about. I went to this wonderful college, Colorado College, where you take one class at a time for three and a half weeks. And because you only have one commitment at a time, it means you can leave campus and do an independent study elsewhere. And so I proposed to do this month-long independent study at SFI on thinking about the physics of ecology and a lot of the scaling work that was going on in those days. And luckily for me, both sides agreed. Geoffrey West and the Santa Fe Institute hosted me. Colorado College gave me a grant to come. So I had support for that month. And I came and did independent research for a month and it was really just one of my favorite months ever and the rest is history, I guess. 

Abha: And you're still working with Geoffrey. 

Chris: I'm still collaborating with some of those same people. 

Abha: I'm curious though, I know you don't like to do experiments and you've sort of stuck around in the thinking sphere of, you know, astrobiology and now complex systems. Why do you want to, even though you know that verifying certain experiments would be interesting for your own work, you would like to stay on the thinking side of things.

Chris: Well, I think thinking happens in all parts of science. You know, there's a rigorous logic to doing interesting experiments. And I have really wonderful experimental collaborators where the logic, the thinking through controls, testing multiple hypotheses, how to identify false negatives and false positives is just sort of amazing to me coupled with amazing technology. So I have a set of really fantastic experimental collaborators who have, to me, mind-bending technologies in their labs and I'm really fortunate to get to work with those people. My talents are more on the theoretical side of things. I was not good in the lab and I'm not good in the field. It's interesting, I spend most of my hobby time outdoors but I'm not a fan of doing work outside. So even though I love being outside, I love being in nature, I love trail running, I love mountain biking. What I discovered is when I'm outside, I want to be relaxing. And when I'm doing hard science, I like to be at a desk. And so it's a, it's just a very funny sort of personal preference that that was not a combination for me of, of how to put those things together. 

Abha: You know, you've worked on so many projects as SFI and it almost seems to be multiple ways of looking at life in general, I guess. How do you keep track of all these things? 

Chris: To me, all of these things are sort of the same thing. I'm interested in what life is. So cities and bacteria and human institutions for me are just different forms of life. And so in my own mind, it's actually much narrower than it seems from the outside, because I'm interested in how do different architectures different scales, different sizes of entities, different amounts of complexity, change what life is doing. And so for anything I'm working on, if I was really pressed on it, I'd say, well, I'm really trying to use that system to understand something deep about life. And there are lots of things I don't work on because they don't fit inside that boundary. 

Abha: How do you define complex adaptive systems? 

Chris: Well, they're complicated and then they adapt. Um, I'm joking. Ao for me, complexity science comes down to  a certain style of question. So really trying to find  regularities and laws and simple theories, but that's not the only aspect of complexity science. Obviously, lots of disciplines do that. The history of physics tried to do that. Lots of chemistry tries to do that. It's trying to find these regularities and these laws. For systems that are at this sort of new level of, emergent dynamic.  And so I'm a big fan of Phil Anderson's “More Is Different” essay. And for me, one of the key features of that essay is, and we've talked about this a lot in the podcast, are these effective theories where you get a new level of organization where you screen off  lots of the lower level dynamics and things combine in some sort of emergent way to give you this sort of new type of dynamic and sets of patterns and so forth. What's interesting then is discovering the new laws for that new system. And Phil was trying to say, in many cases, the amount of variety that you get at some new level might mean that for each system, you have to figure out what the laws and mechanics are and so forth. And so for me, that's the richness that really defines complex systems is, you get this new emergent level, and we haven't discovered the laws of that yet, and we want to, then there's this other aspect that many people talk about for complex systems, which is the adaptive part. And so part of what that's saying is that the objects and the rules and the mechanics and the laws of the system may not be fixed in time, because the system may be responding to itself, may have sort of strange feedback, may be learning. And so that might give you the need  to have theories that are where the laws and the mechanics and the objects are evolving in time and those are hard theories to work out as well. And so that's another dimension in which these systems add richness.

Abha: So when we were interviewing all the people across the episodes in the season, were there any perspectives that you disagreed with? 

Chris: It's a little bit unfair because all the people we picked are people I respect and work with and collaborate with. And so there's a lot of agreement amongst all of these different perspectives. But I think for any conversation with a close collaborator, the disagreements are always in the subtlety. Even for me personally, I think one way about a topic on one day and a different way another day. I think for open problems, we're constantly going back and forth between two different ways of looking at something to try and get traction on really difficult challenges. So I'm sort of a pluralist when it comes to these hard open problems. And some of it is semantic. So, you know, there was some discussion of the new laws of physics that Schroedinger said we might find looking at life. And that really comes down to me about to what you mean by a new law. Is that a new emergent law like David Krakauer and I talked a lot about, or is that some new fundamental force of the universe that's yet to be discovered? And people get into all sorts of disagreements about that. But I think even in conversations with my collaborators, we find ourselves on either sides of the same debate multiple times. I'll be having a debate with someone and think, two months ago you were on the other side of this and I was on the other side of this, and now we've each reversed our positions and we're having to debate the other direction. And I think that tells you what true frontier science looks like, where you're shifting perspectives to try and gain traction and find new ways to look at something and to eventually get to something that we all agree on. 

Abha: Can you describe some of your research and scaling in human organizations? Who did you work with? How does it fit in with Hyejin’s work on cities? 

Chris: So a large group of us at SFI, Hyejin Yun, Geoffrey West, Sid Redner, Vicky Yang, who's now at MIT, and a whole bunch of really wonderful postdocs spread across those institutions, trying to understand what we call the laws of regulation. And so this is one way to think about scaling in human organizations, but also scaling in different types of organisms. What we're really after is why you see across the tree of life, from bacteria to large organizations, some investment in regulatory function. Why do organisms spend resources, whether that's energy or money or time, regulating other functions? We often bemoan this as bureaucracy, and many people would say useless bureaucracy, but why do we spend so much effort and resources on having some amount of overhead regulatory function? So we're trying to write down very general theories for that. We're looking at lots of interesting data that span bacteria to cities to human organizations and just understanding how the amount of regulatory function changes with the size and complexity of a system and whether that's optimal or not. Our argument in part is you see lots of regulation in bacteria. Bacteria have an enormous capacity to refine their function. They have huge population sizes and because of that they can see really small changes in fitness. And so many people have argued that if something is irrelevant in bacteria, it gets selected out by evolution quite quickly. And so if a bacterium has a lot of regulatory genes, those really are doing something useful. That is not a relevant bureaucracy. That is something fundamental to those cells. So we're trying to take what we understand from bacteria and then scale it up to lots of different systems to just ask questions about what optimum regulation looks like. 

Abha: So evolution in living systems and non-living systems, would you say it is the same? Are there characteristics that transfer over clearly or are there some barriers? 

Chris: So it's really interesting to think about evolution in different systems. So, you know, the evolutionary analogy gets applied to markets and companies all the time. But if you look at companies to say, well, it's not exactly the evolutionary dynamic we have in cellular systems. Because it's not like one company grows and gets bigger and bigger and then divides into two little independent companies and those go back into the market and they both grow and divide and then there's selective forces deciding which company is better as they all compete against each other and so some companies die and others keep growing and so forth. Instead what we see is that companies are born, they grow, they die at some point, but they don't necessarily have direct inheritance to other companies. They have some inheritance because people from past companies get hired into new companies and lots of people read case studies about past companies and try and understand what happened with companies in the past. So that itself is an evolutionary dynamic, but it has a very funny sort of inheritance that isn't exactly the rigid inheritance we see with a genome. And yet when we look at companies, we see a lot of the same things that we see in organisms. We see nonlinear scaling laws and we can take those nonlinear scaling laws and turn those into really interesting growth relationships. This is a work that a bunch of us have done. We have really nice predictions for how companies grow in time where we're using a very similar theory to what we would for organisms, asking how mammals or bacteria grow in time over their life cycle. And so there's some sort of evolutionary dynamic there, but it's a little more complicated than what we have with genomes. 

Abha: So, let's bring the conversation back to Heather Graham. And I remember like we used to have these coffee mornings and you mentioned working with Heather back then and the Bennu mission. And I remember you were very, very curious and very excited about it. What do you hope to learn from the raw ingredients from an asteroid itself? 

Chris: In terms of why I was excited about Bennu, I'm excited about any sample return. You know, I'm just excited for any time we get whole other systems encapsulated beyond Earth that we can bring back and ask detailed chemical compositional structural questions about. You know, one problem that we really face for life on Earth is that everything that we're interested in becomes affected by life. So if you're asking questions about, well, what does an abiotic mineral system look like? On earth, you have to work really hard to get an abiotic mineral system because most of our mineral systems are affected by a coevolution of life and the geosphere of this combined biogeosphere. And so I'm just excited to see radically different environments to get a sense of how different things might look from what we have on earth. That's sort of an essential ingredient for starting to understand how contingent our own evolutionary history might be. 

Abha: Talking of, you know, beyond Earth, Heather mentioned a phrase during an interview, I don't know if you still remember it, Heather says, Earth has been many planets. And I’m wondering if you could elaborate — what do you think they mean by that phrase?

Chris: So I think when Heather says Earth has been many planets, it's really to say that if we go back in time on Earth, if we take a time machine back to different eras of Earth, many of those times would be unrecognizable to us, and some of them would be unlivable for us. So one of my favorite examples is the Carboniferous. So the Carboniferous is about 400 million years ago. It's when you get the evolution of land plants and trees come on the scene and all sorts of things that are interesting or happening. Now the world at that time is much warmer. It's a swamp and there's 40% oxygen in the atmosphere, which is roughly twice the oxygen we have in the atmosphere today. So what that huge amount of oxygen in the atmosphere allows you to do is have giant insects. I was actually on one very famous fossil bed from the Carboniferous where you can see millipede tracks preserved in the siltstone and those tracks are like 10 inches apart. Right? So you're thinking about millipedes that have legs that are 10 inches apart. And it starts to give you a concept of just how big the insects in this period of life was. Insects are strongly limited. Their size is strongly limited by the fraction of oxygen in the atmosphere. So that's a radically different world than what we have today. You know, it's a swamp, but you get these big forest fires because everything catches fire because, you know, imagine half the room is oxygen, roughly, like it's really easy to start fires. And so it's a really different period in Earth history. If you go farther back, you get even stranger worlds. You know, oxygen, for example, wasn't in the atmosphere in today's abundance for a long time. I mean, you have tiny, tiny concentrations of oxygen in the atmosphere for a long period in earth history. And it's oxygenic photosynthesis, this radical evolutionary innovation where cells figure out how to turn photons into energy, which is just hard to do. It's hard to capture photons and use them in a useful way inside the cell that comes with the byproduct of producing huge amounts of oxygen that oxygenates the entire atmosphere of the planet and is why we have oxygen today. And so it's that deep thinking where that world, you know, the pre oxygen earth, all the chemistry is different because of how reactive oxygen is. The organisms that live there are different. We couldn't live there at all. So that's, if you just saw that world, if we had another earth orbiting the sun at roughly our same radius, and it was just that earlier Earth we would look at and say, wow, this planet couldn't be more different than Earth. And so that's really to say that the Earth as a whole planetary system has evolved in time. And so looking back at past Earths, they're really not the same Earth we have today. 

Abha: That's so fascinating, right, to think that the Earth that we know is not always the way it is. At the end of the first episode, Geoffrey reflects on the knowledge he's gained through his work on the scaling laws and says that it makes him feel connected to everything around him. How has your work in astrobiology shaped the way you move through the world or the universe? 

Chris: This is another place where I go two directions. Where sometimes I feel very connected to the universe and at one and other times, unimaginably small. You know, this is something that everyone from Calvin and Hobbes to the old philosophers have talked about. Sometimes I'm thinking, well, there's this general theory and it explains how, you know, life might arise anywhere on all these different planets. And I can take that two directions. I can say, that's wonderful. You know, I can sort of understand myself in the context of these universal patterns that happen everywhere in the universe. Or that can make me feel quite unspecial, right? I'm just another iteration of some, you know, form of life that grows up everywhere. But understanding me, my preferences, what art I like, what music I like to listen to, what books I read, the individual relationships I have in my life. I don't think certain theories will ever touch that. I think that's a place where we will always need art and literature and personal experience to sort of describe the individual. And so in some ways, I think it's where our universal theories fail that these more rich and detailed descriptions come into focus. And so that allows me to feel both sort of unimaginably small from some perspective of a universal theory of what's going on in the universe, but also still feel important in some sort of way that the only way to describe me is to sort of be me. And that probably isn't a place that theories can help us. So, that's part of how I mediate that tension for myself. 

Abha: So, you know, we started out the season with very ambitious ideas. And when we had our first discussion, there were so many things that you wanted to touch upon. Is there any topic that you wish you could have touched upon that we haven't yet? 

Chris: I mean, there's just so much amazing stuff happening right now in the physics of life. There's this whole field of active matter which is thinking about, you know, when the matter isn't passive, when it uses free energy, when it has some sort of internal activity, what sort of dynamics do you get from that? And then I would say economics. You know, I think a lot of the ways that these physical theories of life start to interface with economic systems, and we have a lot of active work going on in that, and we didn't bring on any of our, you know, economist collaborators as guests. So those are all areas that just have amazing stuff happening today.

Abha: You know, the first episode was actually recorded with you and Geoffrey at the Complexity Global School in South Africa. And you're going to be going off to the Complexity Global School that's going to be held in Colombia this summer. Could you mention what sort of a school it is and, you know, what you would be talking about there? 

Chris: So these Complexity Global Schools are focused on emerging political economies. And so this is lots of new ways to think about economic and political systems. What are the theories of those? What case studies do we have? How do they interface with some of the biggest problems in sustainability and climate change? And these schools are fantastic. I think I really enjoyed the one in South Africa. Geoffrey and I both had a fantastic time there and gave lectures on different things. What I'll be lecturing on in Bógota is a lot of these scaling perspectives on cities, waste production around the world and the growth of companies. So basically how we're turning a lot of the scaling laws into understanding urban systems, global challenges around waste, and then also dynamics of entities within markets like companies. 

Abha: That sounds like some really fascinating work, and I should say that if any listener in Latin America, North America, or Western Europe is interested in exploring new ideas about economics, policy, and governance, we encourage you to apply. The Complexity Global School will be held this July in Bogota, Colombia, and we’re accepting applications until April 22nd. You can find more information about the Complexity Global School on our website, and we’ll have the link in our show notes, too. Well Chris, I hope you have a great time in Colombia this summer and it's been wonderful co-hosting this podcast with you. I think we've learned a lot along the way and I hope you've enjoyed it too.

Chris: Thanks so much, Abha. It's been a joy co-hosting this with you. And on a personal note, I'm looking forward to the next season just as a listener.

Abha: Yes! Stay tuned for more information about our next season when I will be back with a different SFI researcher as co-host — if you want updates on future episodes, make sure you’re following or subscribing to the show in your podcast app.

Chris: That’s all for this season of Complexity. Thanks so much to the long-time listeners who have stuck with us, and to the new listeners who have joined us this year. 

Abha: Complexity is the official podcast of the Santa Fe Institute. This episode was produced by Katherine Moncure, and our theme song is by Mitch Mignano. Additional music from Blue Dot Sessions, and the rest of the sound credits are in the show notes for this episode.

Chris: I’m Chris, 

Abha: I’m Abha,

Chris + Abha: Thanks for listening.


Through repeated reactions in, um, no not repeated… oh gosh. The glasses are doing nothing.