COMPLEXITY: Physics of Life

Olivia Judson on Major Energy Transitions in Evolutionary History

Episode Notes

It’s easy to take modern Earth for granted — our breathable atmosphere, the delicately balanced ecosystems we depend on — but this world is nothing like the planet on which life first found its foothold. In fact it may be more appropriate to think of life in terms of verbs than nouns, of processes instead of finished products. This is the evolutionary turn that science started taking in the 19th Century…but only in the last few decades has biology begun to see this planet’s soil, air, and oceans as the work-in-progress of our biosphere. The story of our planet can’t be adequately told without some understanding of how life itself depends on opportunities that life creates, based on the energy and mineral resources made as byproducts of our metabolisms. A new, revelatory narrative of the last 3.8 billion years refigures living systems in terms of thermodynamic flows and the ever-growing range of possibilities created by our ever-more-complex ecologies. And in the telling, this new history sheds light on some of the biggest puzzles of the fossil record: why complex animals took so long to appear, why humans are the way we are, and maybe even why the sky is blue.

This week’s guest is evolutionary biologist and science journalist Olivia Judson, an honorary research fellow at The Imperial College of London who received her PhD from the University of Oxford and whose writing has appeared in The Economist, The New York Times, The Guardian, and National Geographic. She is also the author of the internationally best-selling popular science book, Dr. Tatiana’s Sex Advice to All Creation. In this episode, we discuss her work on major energy transitions in evolution (the subject of her next book), and what we can learn by studying the intimate dance of biology and geology over the last 4 billion years.

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Olivia’s Website.

The energy expansions of evolution” in Nature.

The Atlantic on Olivia’s essay.

Music by Mitch Mignano.

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Episode Transcription

Michael: So, Olivia Judson, it is a pleasure to explore complexity with you today.

Olivia: Thank you.

Michael: You gave a superb talk last night on the dance of rock in life, a public presentation of this piece that you published in Nature in 2017, “The Energy Expansions of Evolution.” So, this is the paper I want to reference for this talk, because this is a really, a fascinating synthesis.

Maybe the correct place to start is just to have you lay out the most basic outline of it, and then we can dive into more detail.

Olivia: So, I came to this project sort of indirectly. It wasn't my plan to look at the coevolution of life and Earth, the way that life has shaped the planet and the planet has shaped life over its 4.5 billion year history, but I came to it sort of by accident. I've found it absolutely fascinating ever since.

As I started to understand the extent to which living organisms have shaped the non-living world, I started to ask myself whether I was just making an enormous list of impacts from everything from the color of the sky to the number of minerals here today. I realized that actually I did see a pattern in the history of life and Earth.

That pattern, you could say it like this. The history of life on Earth can be divided into five epochs, each which corresponds to organisms evolving to use a new form of energy. The thing that is very interesting to me about this is that although the first two forms of energy were present when the planet formed, the remaining three are all consequences of this dance of rock and life.

There are events in the evolution of life that feed back into the evolution of the planet, which then goes on to shape the future evolution of life.

The energy epochs are geochemical energy, which you could sort of think of as rock energy, sunlight, oxygen, flesh, and fire.

Michael: Excellent. So, yeah, this is a fresh way of looking at this. I mean, it seems in retrospect, The Atlantic wrote a piece on this when you first published this where they interviewed a bunch of other researches who were like oh I wish that I would have said it first. It's like one of those papers that seems so obvious in retrospect.

One of the things that your paper does really well and that you did really well in your talk last night was to explain how the availability of energy resources determines the pace and the timing of major evolutionary transitions. There is, for example, a prehistory to flesh eating and a prehistory to the aerobic metabolism. I'd love to hear you talk about that and how this changes the way that we think of the step-wise order in which new evolutionary innovations lead to new niches, and so on.

Olivia: So, one of the things that I learned... When I started this program, I didn't really know anything much about Earth history. I came to understand as I read more and more about it. I realize more and more how ignorant I had been, and it made me see that the picture of evolution that I had learned as a student, which was very much based just on thinking about genes and DNA and information, was not sufficient to explain some very long periods of delay in our history. Delay with respect to explaining why, for example, did it take four billion years for the first animals to appear?

Why did it take more than 300 million years for oxygen to accumulate in the atmosphere after the bacteria that produce it here appeared? I started to understand that actually the broader trends in evolution when you're looking over Earth history that they can only really be understood in context with the planet itself. Just thinking about information alone isn't really enough to explain some of these very long periods of delay.

But in fact that there is a resource problem. I focused on energy, but of course there are multiple lenses through which one could look at this subject. You could also focus on limiting nutrients. Like is iron going to be available? Is zinc going to be available? There are people who have studied the sort of trajectory of evolution in the context of the chemical availability that changes over planetary history in response to the activities of organisms.

So, to give a particular example, all eukaryotes, which is every organism you've ever seen with your naked eye. All eukaryotes use zinc in their proteins, but zinc does not actually become available to organisms to use, not widely available anyway, until after you have oxygen in the atmosphere.

So, eukaryotes evolve, and there's already oxygen when they do, but then there's a long period of delay before eukaryotes become abundant. That, I think, remains mysterious, actually. I don't think we understand why that is the case. There are a couple of ideas. One geological, one ecological. Maybe it's both things together.

So, you see around 800 million years ago, which is a billion years after eukaryotes first form, you see that eukaryotes are starting to diversify in the fossil record. But you can sort of say, well, is there something we didn't understand about the fossil record? Is it just that perhaps there was more diversification and it didn't fossilize? But there's an independent question that you can ask, which is because eukaryotes use zinc, you can also say does anything change in the zinc cycle?

This is very recent work that has come out that is not mine, but very recent work that has come out looking at how the draw down of zinc occurs over time. Actually you discover that the zinc cycle changes at exactly the time you would expect based on the fossil record of eukaryote diversification. So, you have two parallel independent confirmations that actually, yes, there was a one billion year delay, which I find fascinating.

Michael: Something like this, you mentioned in the paper, around the Great Oxidation Event — that photosynthesis floods the atmosphere with oxygen, but it takes forever. You mentioned that a lot of this has to do with natural geochemical cycling, the re-uptake and absorption of oxygen by the rocks themselves. We had to reach a sort of critical mass of photosynthetic cyanobacteria that in order to actually create this shift in the composition of the atmosphere that enable the proliferation of the aerobic metabolism that already existed. Right?

So, there's something kind of easily generalizable, universal about this — about the nature of innovation and the notion of “an idea whose time has come,” if we can kind of try and connect innovation and human activity to evolutionary innovation. I mean, I'm curious what you see as the abstract or universal there.

Olivia: Well, I think that there are two things. I mean, I think that you can certainly say that there are limitations. There are constraints. Those constraints cannot be overcome until, for example, you either have a new energy source or a new way of using that energy source. So, one of the great innovations in the history of life is the evolution of the eukaryotic cell, which does seem to have been a unique event in four billion years of evolution.

That, I think, raises some interesting and important questions. It's hard to know exactly how to phrase this, but how did it come to be that this was able to happen, when it seems like... I mean, from my point of view as eukaryotes, it sort of seems like an inevitable event. But when we look at Earth history, I think we can say that actually it was an extremely unusual thing to happen.

And I don't think there's necessarily any inevitability around it, but I don't know. I'm not sure that I'm managing to answer this question at all, actually. [Laughs]

Michael: You mentioned in the origin of eukaryotic cells, “In extant eukaryotes, organelles and mitochondrial origin take several different but related forms. Notably only one, the standard mitochondrion found for example in humans, requires oxygen. Three others are involved in forms of anaerobic metabolism.

These observations fit with the hypothesis advanced by Martin and colleagues that the ancestral eukaryote resulted from a prior symbiotic association between a hydrogen dependent archaeon and a metabolically flexible alpha proteobacterium that in the absence of oxygen lived anaerobically producing hydrogen and in the presence of oxygen, lived aerobically. If this hypothesis is correct, the ancestral eukaryote could have been a facultative anaerobe, able to live in both oxic and anoxic environments.”

So, this question of the innovation before it stabilizes is an interesting question. How, much as we saw with the Cambrian Explosion, innovation, it seems to go through a sort of radiative exploratory phase where the selection pressure is on flexibility. Then it settles into something a little bit more formal and concrete.

Olivia: Well, I mean I think I think about evolution a bit differently. I think one of the people who... So, Stuart Kauffman who obviously has been a long term associate with the Santa Fe Institute, coined the term “the adjacent possible.” And I think that one of the things that we have come to understand is that natural selection and evolution, they're not magic wands. Right?

Evolution by natural selection only works if each mutational step itself is advantageous. So, you have a mutation. And there's no such thing as advantageous in a general sense. It's advantageous in the circumstances you're living in. So, it's very environment-dependent what is advantageous and what isn't.

But just because something would be useful doesn't mean it will necessarily evolve, or it doesn't mean it will necessarily evolve soon. So, one of the clearest demonstrations of this, I think, has come about from the Lenski very-long term evolution experiment on E. coli bacteria, which has been going on I think since 1988 or 1990. And every day somebody changes the E. coli from one vat to another. They grow, and it's gone through 70 or 80,000 generations now, I think. So, it's a very long term evolutionary experiment. The bacteria are growing in a very circumscribed particular lab environment, but it's been constant for the whole time.

But the interesting thing is that in the growth medium there is something called citrate, which E. coli cannot normally grow on, but it's very abundant whereas glucose is limited. So, you would expect that if it was advantageous to be able to eat this stuff, the citrate, that it would evolve. But in fact in the 12 populations, at least the last time I checked, in the 12 populations it had only evolved once and that only happened after about 35,000 generations.

So, it's a nice demonstration of how in order to find an evolutionary solution, sometimes there's a lot of meandering, and there's no particular direction to the solution. The E. coli probably don't even know there's a problem, so to speak, that they're trying to solve.

The reason that they're able to solve it is because they reproduce very quickly, and also in very large numbers. So, if you're a bacterium reproducing very quickly in large numbers, you get to explore the mutation space pretty reliably.

But it turns out that there's a path dependence to get to being able to use the citrate. So, in order to get the mutation to use the citrate, you have to have at least one or two other mutations first that have to join up. So, that's why it was only in one of these 12 populations.

The thing that's nice about the Lenski experiment is that every 500 generations they freeze some of the organisms. So, in principle, they can restart from any point in the past and do it again. They did this, and that's how they found that there was actually a facilitating mutation on the road to citrate use. I think the point of this is that sometimes just because you want to get there from here, doesn't mean it's easy or straightforward or direct. I think that that's one of the possible explanations for why the eukaryotic cell has only evolved once.

First of all, I think it's actually very difficult, because although we think of internal parasites or symbiotes as being very common in biology, they're actually only very common in eukaryotes. It's a feature of eukaryotes that they can have other organisms living inside their cells like bacteria, for example.

You see this in insects. A lot of time you see it in the other human gut microbiome and so on. You see that there's a lot of intimate associations with other organisms inside the body. In bacteria and archaea, which are both prokaryotes, you don't actually see this. Now, it's possible that we haven't sampled it enough, because so many of these organisms are obscure to us, and we've never managed to even see them with a microscope let alone to grow them in the laboratory.

But I think that from what we can see, internal symbiotic associations are very, very rare. So, I think of it as a double problem, the evolution of the eukaryotic cell. It's getting in and then getting along. I think both are hard problems, but I think that it's also not necessarily clear, that at least in a microbial world, that there's any particular advantage to being a eukaryote. So, it's not clear that there was any drive towards that either.

Michael: I know that you went to Oxford with David Krakauer, right? As we were just talking about before this recording, my entrance to complexity was with the work that he coauthored with Martin Nowak and Princeton on the evolution of syntax. The immediate application that I saw was to taking that math and applying it to the origin of complex cells or to multicellular life. There do seem to be...

And again this is maybe a tangent, because this is more, again, about sort of informational crisis and message transmission. But, this notion that there reaches a point where each individual word and the memory required to hold all words that are relevant for communication in the population demands more memory than is effective for coherent communication.

So, syntax emerges as a way of keeping the collective computation intact at the community level. So, something like this seems to be at play here. Then the question is, can you look at the origin of eukaryotic cells as being driven by energy limitations or the fact that teamwork emerges as a strategy within a resource limitation context?

Olivia: Well, I think the question is very complex. It's clear that bacteria and archaea often live together in very intimate associations. It's just that they stay outside each other. So, you'll have a cell with many other cells attached to it. Often those other cells are doing a very important job.

So, if you're a small cell giving off, say, hydrogen gas, you can drown in your own waste products even if the hydrogen gas is only a sort of small envelope around you that's less than a millimeter thick. But if there are other organisms there that are pulling the hydrogen gas away, then you can continue to produce.

So, you have very intimate associations going on in microbial communities already that are dealing, in fact, very effectively with some of these resource limitation questions. I think that the eukaryotic cell does something else. It is an observable fact that in four billion years of evolution, bacteria and archaea have both remained extremely small.

In terms of volume, archaea span six orders of magnitude and bacteria span nine, but they're still very, very tiny. Only the very biggest bacteria, which are the by the way outliers, only the very biggest bacteria are visible to the naked eye, the naked human eye.

I think what the eukaryotic cell seems to have done is relieved some kind of architectural constraint. Exactly the nature of that constraint is not very clear and disputed. But if you look at the structure of both bacterial and archaeal cells, the internal structure is generally much simpler than in eukaryotes. In particular, they use their external membrane for generating energy. The DNA is not separated from the rest of the cell. So, there's no separation between information and energy in bacterial and archaeal cells in the sense that everything is sloshing around in the same compartment.

In particular, they have this external membrane that is generating energy and that cannot be disrupted without critical consequences for the cells. So, even a virus, and obviously bacteria have viruses and so do archaea, but even a virus…

So, a virus doesn't go inside a cell. It injects its DNA, or its RNA, but let's say DNA. It injects its DNA into the cell, but it does it very elaborately and with a kind of hypodermic needle that doesn't really disrupt the energetic activities of the membrane.

So, it has come to seem to me that what the eukaryotic cell does is it relieves some kind of architectural constraint. Because the mitochondria, which were bacteria once, mitochondria are what's doing the energy generation. So, the energy generation moves from the outside of the cell to the inside of the cell.

Once you've done that, it frees up the external membrane to do other things. So, it's only when you have this symbiosis firmly established and these two organisms have fused…I have to say that it's a very complete fusion. I mean, they really have become one. To just sort of say, oh well the mitochondria used to be bacteria is very insufficient to explain what happened or describe what happened. I mean, when you look at how chimeric and mosaic eukaryotic cells are with all kinds of bits from bacteria here, like the membranes are all bacterial. A lot of the DNA processing is archaeal, but in fact even within that there is some bacterial contribution and a lot of bacterial metabolic genes.

So, it really, it's a very composite organism that then goes on to evolve its own stuff, obviously. But it's a very composite organism. It seems that this switch from having energy on the outside of the cell to inside of the cell is what actually relaxes some sort of constraint. The nature of that constraint, I think, is still being explored.

Michael: So, this issue that you've brought up a couple times here of larger organisms and more abundant energy leading to a diversity of metabolic strategies means ratcheting niche construction, right? So, you say from the point of view of the biosphere, the emergence and diversification of eukaryotes provided a new set of niches for prokaryotes to occupy, which in turn allowed eukaryotes to occupy far wider variety of niches.

So, this notion that the microbiome and, at the bacterial level, the proliferation of new food sources is an example of this driver. I'm really curious to hear you go into more detail about niche construction and ratcheting biodiversity and how that's driven by these energy expansions.

Olivia: So, the way that I've come to think about it is as organisms evolve to use a new energy source and then go on to produce new energy sources, you get two things happen at the same time. You get an expansion of the complexity of ecological interactions, and you get an expansion of the geological impacts on the planet.

That comes around in two different ways, the geological impacts. Because on the one hand you have organisms living in a wider variety of places. So, one way to think about it, I think, is that as ecosystems become more complex and diverse you also have an expansion of the habitable area of the Earth.

So, this brings me to a sort of pet peeve of mine, which is the idea of habitability. Because I don't think it's very useful to talk about habitability, because the question is, habitable by what? I think when you look at the history of the Earth, you can see that actually the question of “habitable by what” has itself been changing and evolving as these ecological and geological things have been going on together.

So, I think when you look at the evolution of animals, for example, you can see that this expands the habitable portion of the Earth in several different ways. First, each animal surface becomes an opportunity for much smaller organisms.

Michael: Okay, so the adjacent possible is a great thing to bring up here. Because when I think about this, again, in terms of the idea whose time has come, it gets to, in design terms, the affordances of the built environment. One of the things I love about your articulation here, your synthesis, is that it sort of democratizes the so-called Anthropocene. It makes it a process that has been continuous with this greater process of niche construction that's been going on for four billion years.

The elephant in the room is [James] Lovelock and Gaia, right? And this notion that life creates the conditions for life. There's something really beautiful about showing that there are ways that human beings are distinct. You talked about this last night, our capacity to reflect on these things is an important qualitative difference.

But at the same time, looking at the Great Oxidation Event, for example, as an atmospheric or climate catastrophe that required an innovative response, the pioneering of new metabolisms on this planet, casts our current climate crisis as a consequence of the industrial revolution in a light that seems to give us some very helpful and concrete analogies for how to create our way out of this accelerating sequence of catastrophes that started way before we started interfering with natural systems in any kind of intentional way.

Olivia: I think so. Although the big difference between something like the Great Oxidation Event and today is first of all that it was a very long time in the making. It was 300 million years in the making. And second, so we are operating very, very much faster. I think that that is something very important to bear in mind, because yes we can reflect on it and possibly use it as a way to think about how to move forward, but we shouldn't spend 300 million years thinking about it. [Laughs.]

We should really be thinking about it right now and in some detail and vigor. Because I think that one of the biggest differences between what's happening today and what's happening in the past is the speed at which it's happening and the number of dimensions on which it's happening.

I think that that makes the current situation much more dangerous. Also, another big difference is at the time of the Great Oxidation Event, Earth was only home to bacteria and archaea, which exist as very small life forms in very large numbers, and that gives them a resilience that we do not have.

You can imagine just the glaciations of the recent periods, you can see that that is more difficult for larger organisms to deal with than it is for smaller organisms I think. And I think that if we cause a major climate catastrophe, well, it may not be a problem for the bacteria, but it may well be a big problem for us.

Michael: Yeah. Important considerations. It seems like it's important for us to backtrack just a little bit here and put this all in context, because your fifth and most recent energy innovation is fire. I've always thought of fire as something that has always been around. It's one of the four elements. That's such a common way of thinking.

But something really beautiful in what you've done is give us a step wise layered walkthrough of how everything that we take for granted now was pioneered at some point in history, was new. All classical music was once contemporary.

So, I'd love to hear more about what you've articulated as the three conditions for fire and why it's important for us to understand how rare and special fire on the surface of a planet actually is.

Olivia: So, fire has only been here for about the last tenth of the planet's history. That's because to have a fire, you have to have all three conditions met. First you have to have a way to start one, and that's actually fairly easy. You need lightning or stones falling. Actually a lot of the other planets in the solar system have lightning, but they don't have the other two conditions.

Those are you have to have enough oxygen to support one. You also have to have something to burn. Enough oxygen to support one is about 16% of the present atmospheric level, and that's actually not reached until almost around the same time that you start having plants on land.

Those two things happen more or less together as far as we can tell, because the oxygen may have risen a bit earlier. It's very uncertain the history of atmospheric oxygen. So, you get the Great Oxidation Event, and oxygen appears in the atmosphere for the first time.

But the history of atmospheric oxygen after that, probably it remained fairly low until a certain time in the fairly recent past, which means several hundred million years ago when it begins to, again, rise. At the same time, around 400 million years ago, perhaps a little bit earlier, you start getting plants on land. So, then the three things come together, and you start having the possibility of fire.

In fact, the fossil record shows that that possibility was immediately met. As soon as you could have fires, you did have fires, and we know this because fire leaves its own fossil trace. It leaves charcoal, and charcoal can tell you a lot about the heat of the fire. It can tell you also about the nature of the ecosystem in which the fire burned.

In fact, some of our earliest fossils of flowering plants, which are strangely late to the scene, actually, in terms of evolutionary history…but some of the earliest fossils of flowering plants are in charcoal, preserved in charcoal. So, fire has been around for just the last tenth of the planet's history, but it only becomes available as an energy source for organisms once an organism evolves to use it, and that happens some time around a million years ago, 400,000 years ago when humans began to cook.

This is work done by Richard Wrangham, others, that has shown that when you cook food, you are able to... It's a sort of pre-digestion, and you can get more calories from the same food than you would if you ate it raw. So, this has had a huge influence on, for example, if you cook starches, it breaks down the crystals of starch and makes them bioavailable, basically.

So, if you're eating lots of root vegetables, often cooking them makes them a lot more palatable and makes a lot more of the materials available to you. A number of people have argued that this is one of the reasons that humans have been able to afford larger brains. It's also one of the consequences of eating cooked food.

What Richard Wrangham argues that actually one of consequences is that we have entirely adapted to cooked food. He calls us cocinavores. As evidence for this says that people who are eating an entirely raw food diet find it very difficult to maintain their body weight and also spend enormous amounts of time in food preparation, continually sort of pounding and grinding and blending.

But also evolving to eat cooked food, it had evolutionary consequences on human physiology, but it also means that we don't have to spend all day eating, which is what a lot of great apes do. Some people have calculated that if great apes were to have a brain as extensive as the human brain in terms of its energy demands, they would not be able to do anything except eat all day long if they did not have access to cooked food.

And so, it's with the ability to use fire for cooking that you start to get another shift in the history of the Earth, I think. Because this very rapidly starts to lead to human social changes, which also then go along with tool use that is based on fire. I would argue that almost all modern human technology has its origins in the technology of fire. In particular, the ability, for example, to smelt iron, which requires a great deal of heat.

If you don't have access to that in a controlled way, you simply, you just can't get beyond the Stone Age, basically.

Michael: So, in terms of getting beyond the Stone Age, one of the elegant threads tying all of these different disciplines together is in your discussion of how most of the mineral species on this planet now basically only exist because they've been produced in some way by some living process.

I remember hearing recently that if you take a broader view of diversity beyond biodiversity and look at the diversity of mineral species that due to material science and industrial manufacture and so on, that we're going through what could be argued as, even as we're thinking of this as the sixth mass extinction, we're proliferating new chemicals and new compounds and new materials and new technologies.

So, how do you understand that sort of complex relationship between the growth in biomass, volatility of biodiversity, the ways in which these processes seem to lead to this exponentiation of available parts?

Olivia: Well, I think that one of the things that I think could be said as a general thing that with each of these energy expansions, you get an increase in the variety of materials and in particular the variety of elements that organisms are using. So, when eukaryotes appear, they start to use zinc, which is used a bit by Bacteria and Archaea, which first of all, becomes much more available once you have oxygen, but second of all, you actually evolve new ways to use it. I think that the same when you have the evolution of animals you start to also have the evolution of shells, not only on animals but also on small organisms that want to protect themselves from animals.

That results, ultimately, in a big draw down of the available silica in the ocean, because it's tied up in animal materials or protist materials. So, you do get this sort of expansion of the elements that organisms are drawing on.

I think that one of the things that's happened with the human industrial metabolism, so to speak, is that you have an increasing reach for different kinds of elements. Suddenly, we all want rare earth elements for various industrial uses. So, it's certainly in keeping with this general pattern.

I think, though, that there are deep reasons to mourn the loss of biodiversity. I personally find it somewhat strange that we do not appreciate the wonder and beauty of some of the organisms around us more, and that we do not value that intrinsically more. Because we are surrounded by remarkable organisms that have lived and evolved for millions of years. I find this at least as beautiful and impressive as any human structure, often rather more so, actually.

So, I think that for me personally I would like us to find a way to be less impactful. Not just biodiversity for biodiversity's sake, but something a bit deeper than that, something a bit more…almost spiritual, I suppose. On some level I have a sort of fantasy of an Institute for Planetary Care that would try to improve the lives of humans but also of non-humans…that would be more attentive to, for example, the extent to which our noises impact other organisms and make life unpleasant for them.

Maybe this sounds a bit sort of hokey, but I think there's something deeper there. I wouldn’t like to say so crudely as to suggest that it's a matter of self-preservation to preserve these other organisms as well. But I do think that it will speak very badly of us if we allow them to go, that we just didn't care, and we were too caught up in our own stuff, and too unreflective.

Because I think it's one of those things that when it's gone, it will be extremely difficult to get it back. This is really getting off the track a bit, but I personally think that the idea that oh yes, well, we're going to bring back the wooly mammoth by impregnating elephants. I mean, really?

Michael: I don't think that sounds hokey at all. I think Nora Bateson talks about warm data, keeping things in context where they can be lived and understood firsthand. I think E.O. Wilson has argued for biophilia as not merely just diversity for diversity's sake, but understanding why we value the beautiful within our own evolutionary context. So, I think there is something really important in terms of situating this entire conversation around the cultivation and/or regeneration of biodiversity as part of this greater synthesis that you've articulated here that as the network collapses, all of the niches collapse and you get cascading extinctions, you get secondary extinctions, extinctions of organisms we don't even realize we depend upon.

But there's a sort of disturbing note in all of this which in order to get to I have to bring up this other thing, which is that when I hear this story told it reminds me of research like that being done by John Pepper at the National Cancer Institute on the metabolic theory of cancer and how much like Andreas Wagner has done research on these cryptic mutations that suddenly find a context and suddenly create a bridge between local optima on this fitness landscape. It appears as though the tissues of our bodies are riddled with precancerous mutations that are not actually driving the growth of a tumor and that it's predigesting, if you will, the tissue for this oversupply of energy from whatever it might be, a metabolic dysregulation of some kind, to provide the substrate, the opportunity, for the tumor.

So, for the last few weeks since I saw John Pepper speak here, I've been horrified thinking about our great achievement as human beings, the discovery of fire, as an instrument of technology, and realizing that the industrial revolution doesn't seem like it's just some sort of mistake.

Even though it is contingent on all of these other path dependent settings, it also seems, like you said, like as soon as it could happen, it did. And it's hard for me not to get out of the head space in which human civilization is essentially functioning within the biosphere as a kind of tumorous growth.

Towards the end of your paper, you talk about how the entire Phanerozoic has been characterized by the repeated replacement of low-energy life forms by those able to harness larger amounts of energy. Ectotherms are replaced by endotherms. Not entirely. Gymnosperms are replaced by angiosperms. Again, not entirely. But when I think about this in terms of the work the Geoffrey West has done on scaling laws and cities, and these accelerating returns that we observe in the economy, it seems as though whatever we're in the midst of is a process that is greater than our ability to intervene and that human beings are maybe the gymnosperms or the ectotherms here.

That we are participating in the production of massive server farms and other kinds of industrial infrastructure that are making human environments more and more inhospitable for human beings. So, I'm curious where you see the sort of the map of the problem here.

Olivia: Well, I think it's very profound. The work that I've been doing thinking about Earth history and thinking about how organisms use energy has certainly changed how I see the world. What I'm about to say is probably going to sound very strange, but I have begun to think of organisms as being servants of energy. That we build things because we have the energy to do it. I think this is true of all organisms. One of the things that I've been very interested by is what happens to cyanobacteria when they are nutrient-limited.

So, cyanobacteria are the original organisms that evolved to split water with sunlight to release oxygen. They're extremely abundant. They're probably the world's most important organism, one of the most prolific, one of the most successful in terms of representation in the biosphere. Because you can think about all plants as being a manifestation of cyanobacteria, because the chloroplast which allows plants to use sunlight is derived from cyanobacteria.

So, when a cyanobacterium is unable to make proteins because it doesn't have enough access to nitrogen or to phosphorous, it must nevertheless continue to use the energy it has or else it will break down. So, what it then starts doing is it starts making sugar, but it doesn't use the sugar for itself. It just puts it into the environment. It makes the sugar and gets rid of it, makes the sugar and gets rid of it, makes the sugar and gets rid of it.

So, you can see this situation where the energy is flowing through the organism, and the organism is building stuff that is of no use to itself. This has consequences for the environment, because lots of other organisms then live on this sugar. So, the cyanobacteria end up creating a community around them of organisms that feed on the sugar.

But it has made me think a lot. I started reading some strange and difficult literature in bacteriology which suggests that actually a lot of organisms have a sort of steam valve that they basically let off excess energy by doing one activity or another. I have come to think of organisms as being energetic constructions.

We're always breathing. We always have to carry out energetic processes. These are going on all the time, and the energy is first. I mean, people usually say, “Oh yes well organisms need energy in order to grow, reproduce, move, et cetera.” But I think it's the other way around. I think we do those things because the energy is flowing.

And what humans have been doing is creating much bigger flows of energy. What do we do with those flows of energy? We build stuff. In fact, energy use has been increasing tremendously. As you say, some of it, especially something like Bitcoin mining, seems to me to be really just kind of putting the sugar into the system and keeping the energy is there. It makes me very pessimistic, because it makes me think that we're on a kind of path where even if we were to switch completely to solar, we would still be needing to use all this energy that we have. That use would still be destructive to the rest of the environment. I think that my only sort of hope in this is that it is possible for us to understand it.

If we were to apply ourselves to it properly and to really pull together. I mean, a rowing boat goes much faster when all eight people are rowing at the same speed, you know, and then it really zooms along.

Michael: Less waste heat.

Olivia: Yeah. So, if we were all to pull together, it's possible that we might be able to really find something new and find a way to escape from being servants of energy. I think it's quite urgent. I'm not sure we'll make it. I think that we may be about to discover the answer to the Fermi Paradox, which is where all the other civilizations. I think we may be about to discover the answer to that, which is that you can't just get out of this energy trap. But I would like to hope that we would live up to the name that Carl Linnaeus gave us when he described us as a biological species, Homo sapiens, rather than Homo stupid-ans. [Laughs.]

And that we would be able to really come together. But I think it will take quite an extraordinary cooperative effort, but cooperation is something that humans have evolved to do. Did that sound very strange?

Michael: No. Not at all. The figure ground reversal in this, the noun or verb, object or process. This is a very important distinction when we're talking about whether it's appropriate to use continuous or discreet math. When we're talking about the difference in perception between the cultural east and the cultural west and how they parse and landscape, how they understand the relationship of organism to environment.

The whole conversation around dissipative structures and free energy minimization has been ongoing within the sciences, at least, for decades. But framing this as order emerges as a way of energy seeking rest…it circumvents this tiresome conversation that won't die around whether life is somehow a fifth law. Or that life requires some sort of vitalist principle or anti-entropic principle. It also brings us back to your mention of the importance of acknowledging grief in this, because as a process it's almost a Heraclitean thing, right? That what exists — to put in philosophical terms right? — that ontologically prior is the flow. Then the forms emerge out of the flow.

So, the question of how seeing things in this way situates us with respect to these environmental and social issues: What do we do with extinction? How do we understand our role in the seemingly imminent biotechnological explosion that's about to happen of new kinds of organisms?

But I want to go a little deeper with you, while we still have the time for it, about what comes next. Because in a way it's important over geological timescale to compress every energy innovation that humans have made into fire. Right? That would include, presumably, nuclear technologies and so on.

It seems that though there's a decent reason... I'm afraid to even bring this up. But let's suggest just as a thought experiment that radically new and liberating forms of energy technology have in fact been suppressed. Is it possible that it's actually to our benefit? That if suddenly we were able to realize the ecological dream of abundant free energy, we would turn the whole planet into paper clips, or something similarly stupid.

Olivia: Well, I think that there are several different dimensions to the question. I think that burning fossil fuel has very clear, very detrimental effects. I don't think most people would dispute that. Certainly I don't think scientists would.

So, there's an argument for saying, well, we must stop using fossil fuel as soon as we can, because it is so directly disruptive and so quickly disruptive, and we are seeing those effects. But it's certainly not the only effect, right? I mean, there was a paper that was published either last year or this year by a couple of people looking at just the general heating up as a result of entropy causing activities.

So, just the use of energy and the fact that the conversion is never complete. It means that heat is always released in anything, and you can see it with microbes, too, that they're generating heat. That's why compost piles are warm. You can put your hand in and it's nice and warm, and snakes like to sleep there because of all the microbial heat production.

There are people who have predicted that by 2260 the Earth will have heated up due to energetic uses independently from the carbon dioxide, that it will have heated up and become a bit uncomfortable simply because of the heat that is being generated and that hangs around. I'm not able to really assess this. I'm particularly not able to assess the 2260 figure.

Michael: That's very specific.

Olivia: But I think that there are very important questions around whether or not we would be able to decide as a civilization to say we want to go to a completely different path. It's pretty obvious that all this stuff doesn't make people happy. So, I think there's a question of could we just do something completely different?

I don't know what that would be, and I don't think there's been enough imagining around it. There's a lot of dystopia around climate change. I don't think there's been enough imagining what alternatives are there? Could we step away from this process that we're part of because we can reflect on it and think about it, and choose to do something that is radically different?

I really don't know the answer to that, but I would like to think that it's at least possible that we could start to try. I mean, there are other difficult problems as well in the Earth's system at the moment which have been written about lucidly by Tim Lenton and his colleagues about the need to close the material cycles. We are taking materials out of the earth and using them, but we're very poor at keeping them in the system once they've been used. So, we have all this big recycling problem, especially of some of the metals, and so on and so forth. Even something like phosphorous or nitrogen fertilizer. I mean, nitrogen fertilizer, which at least half of us today have thought to be existentially dependent on. In other words, if we were to take it away, half of us would die immediately, because we would not be able to produce crops. Yet our efficiency of using the stuff is very, very poor.

So, if we were able to develop ways to use things much more efficiently so that a much higher percentage of the fertilizer applied went to the plant instead of just running off and creating havoc in other ecosystems, we would start to be making a much more efficient usage. At least some of the knock on effects of what we're doing would be somewhat reduced.

I think that those are also very important questions to consider. Personally, I would not welcome an enormous unlimited energy source, because I think actually, it would spell D-O-O-M.

Michael: To your point about the cyanobacterial production of sugar, there's a clear economic throughline there in terms of the creation of positive externalities. I'm also thinking about when there was a golden period of cathedral building in Europe, 13th century or so, that was due to the local production of wealth. There might be ways for us to make use of abundance without us allocating it toward mindless expansion.

Olivia: I think they are very deep questions. I think that also evolution has shaped our brains in certain ways. I think that that gives us blind spots. Just as moths flock to a candle, I think that we, too, have blind spots, and it's very difficult for us to identify them, because it's us. There's nobody watching us. If a dog could speak, maybe they'd be able to say, “Hey you guys really don't notice the obvious stuff here.”

So, I think that we have blind spots. I also think that we have tendencies. Certainly the history of humans is very complex and mixed in terms of mixer of corporation on the one hand, very violent aggression on the other. Also towards other organisms. The kind of slaughter of the passenger pigeon just for kind of sport's sake I think suggests a lack of empathy and attention to other organisms.

So, the question is can we overcome some of our built in biases and tendencies to try to step away from this drive for I want more, more, more, more, more, more, more?

Michael: It's almost like as soon as it became possible, it happened. Right? So, did you think that maybe the answer to the question is an economic answer, in terms of the way that our incentive landscapes are shaped by economic opportunity?

Olivia: Well, I think that it would be great for economists to take part in this conversation. I think that it's clear that, left to itself, a free market does not deal properly with pricing of things like pollution. If we were properly paying for things like airplanes, most of us would be on the ground. Because the costs of the pollution are not being factored into the ticket prices. And I think that that's true with many other aspects of our activity. So, the question is could we rearrange the economic pricing so that our incentives are differently aligned.

Michael: A couple years ago, there was a TED talk with Vint Cerf and Peter Gabriel and a few others on the interspecies Internet. Which is both, one, really exciting for the possibility of being able to, like you were talking about earlier, understand the perspectives of other creatures. But it also suggests an attempt on the part of the economy to reach into and appropriate that which has been unmeasured and bring it into the fold and turn dolphins and elephants into customers, not just voters.

And yet, the whole issue of the need of collective computation — again, looking back through a glass darkly at the origins of endosymbiosis, wondering to what extent we can analogize that to really dense, highly connected, intentional interspecies relationships now. Or whether human beings are like the mitochondria within the Internet, this kind of stuff.

We're back in this sort of catch-22 where it seems like the way out of the problem that we've found is to reach into other perspectives, to reach for new opportunities, to the best of the ability that we have been afforded by our energy resources, by our material resources. I don't know. I'm just left with this very darkbright kind of paradoxical thing — which is that, again, economists please join this conversation — to truly account for the full cost of human activity, means to take our quantification, to take our accounting of these cycles and processes and extend it as far as we can to ask questions like, “What is the economic value of one tree in the Amazon?”, to understand that in terms of both its material and energetic flows. And yet in so doing, it just sort of further enclosed ourselves in this runaway chain reaction.

Olivia: So, there's a vogue in ecology to talk about ecosystem services. Just sort of say, well you know, bees pollinate crops, and mangrove swamps protect against hurricanes, and so on and so forth. I understand entirely where the motivation comes from to do this, but it also leads to people saying, “Okay, well let's just make little robots that are going to pollinate the crops instead,” which pisses me off, I have to say.

I also think that as I said while I understand why people are trying to give an economic value to nature and sort of say, “Well, we're getting all this stuff for free. We should think about the contribution we're actually getting and clean water and so on.” I also think that there is an intrinsic value which is different from trying to put a price on everything.

Just in terms of the soothing of the human spirit, so to speak, looking out at a beautiful landscape that there's certainly some data that suggests that if you're surrounded by nature or visions of nature when you're in a hospital bed, you're able to recover better and faster, and that gardening, you inhale bacteria that make you feel good, and that if you go out and work in horticultural-related or an outdoorsy processes, volunteers who do that sort of work are much less likely to be depressed than volunteers who do other kind of volunteering work.

So, I think it's important to think about the psychic effect of some of these losses. And that is different from the economic effect, I think. Personally, I would not like a value put on every ant or every bee or every lizard. I would prefer that we arrive at a system of coexistence, even within this difficulty that we have that we are apparently driven to dissipate energy.

Michael: So, that is the question, right, which is how do we accept our role as servants of energy, yet give an intrinsic value to the myriad ephemeral forms that it produces?

Olivia: Well, I'm not sure we should accept our role as servants of energy. I think we should try to escape.

Michael: What would it look like to throw our shoe into this machine? To reject our role in this process?

Olivia: It would mean arriving at a very different kind of economics, I think. I'm not sure that that would be a mistake, because I really don't think the...I mean, it's very clear that material comfort makes a difference from abject poverty to basic material comfort. That makes a very big difference in terms of welfare and health and opportunity and happiness.

But it's not clear…I know plenty of very wealthy people who are not happy. So, they're very comfortably unhappy, but they're still not happy. So it seems like the economic situation that we've generated doesn't actually seem necessarily in keeping with a lot of aspects of what humans actually like.

What do you think? Have I been saying very strange and weird things?

Michael: Not to me, but I'm kind of strange weird person. I frankly don't know how they decided to trust me to host this show. I want to bring this back to one of the more important points in this piece. I think it's easy to get lost in arguing about some of these more philosophical dimensions of value and diversity and so on.

But you ended your talk, and you end this piece with a sobering reminder that your synthesis is a story of how something can't happen until the conditions are ready for it to happen. So, on a planet we might otherwise consider Earth-like, if the rocks absorb oxygen more than Earth's did, that it may never actually make it onto the next plateau. It may never actually develop the kind of rich land-based ecosystems that we have here that seem a sort of necessary precursor to the next thing.

One, we clearly need to reframe how we're thinking about our search for Earth-like worlds. That is really about adding the time dimension and the dynamical systems dimension to this. Understanding that for most of Earth's history it wasn't habitable to human beings.

You had a great line in your talk last night about how you would be constantly jetlagged if you took a time machine back four billion years, because the planet was spinning at a different speed. So I'd like to hear you elaborate on that in terms of recognizing the precious uniqueness of the system that we have.

All other things, all other abstract questions about where we are in the process and our responsibility to it aside, what do you see as the simplest takeaway from viewing life history in this way?

Olivia: I think I've learned two things. The first is that the Earth is not static. So, what the world that we experience is really a life-earth co-production. It has been evolved over very long periods. Everything from the variety of minerals to the oxygen that we breathe in the air and so on. So, I think that it wasn't just sitting here until humans appeared. We emerged out of a very long, ongoing process, and we find the planet beautiful and very comfortable because we emerged at a particular time, and we fit with the environment because of that process.

So, that's one thing, but the other is I would be amazed and delighted if we discovered that, for example, Mars has some sort of microbial life living deep within it. It would be so exciting, because we could ask fundamental questions about the nature of life and the origin of life and perhaps understand more things about how life emerged here, and so on and so forth.

If we discovered microbes in the oceans of Saturn's moon Enceladus, it would be tremendously exciting. But we don't have to go there to know that even if there is life there, what happened here is fundamentally different. This landscape or this process of evolution and energy and evolution and energy that has resulted in the world we experience, that hasn't happened in those places even if there is something alive.

So, it is my belief that if you want to talk about Earth-like planets in terms of a wet rocky world not too far from a star, it looks like there are probably uncountable millions. But if you want to talk about an Earth-like planet in terms of “comfortable for humans,” it's possible that there is only one. We're already here.

Michael: Hopefully we're here for awhile. Hopefully we're here long enough to read your book. When is that coming out?

Olivia: When I finish it.

Michael: Sometime next year, maybe, hopefully?

Olivia: I don't know. At my current rate, another 300 million years, but we'll see.

Michael: Okay.

Olivia: Very patient publisher.

Michael: It happened as soon as it could.

Olivia: That's right.