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- [Man] That's beautiful!

- Yeah!

- Welcome to After Dark Online. Thanks for joining us again as we continue to explore our world through science, art, and conversation. My name is Sam Sharkland, and I'm a program developer as part of the team that produces After Dark. And though this program is virtual, the Exploratorium is located on Pier 15 in San Francisco, on unceded territory traditionally belonging to the Ramaytush Ohlone. We recognize that we are guests on this land, and we honor the conservation and stewardship the Ohlone have offered the ecology we inhabit, past, present, and continuing into the future. This month at After Dark Online, we're looking at the theme of sustenance. What are those attributes or pieces of culture that nourish us and will carry us and sustain us through the future? Tonight, the topic is animal intelligence. We're really lucky to be visited by Peter Godfrey-Smith, author of the recent book "Metazoa," previously of "Other Minds." You may know him as the author who explored the intelligence of octopus. In this book, "Metazoa," Peter Godfrey-Smith expands the thinking about where animal intelligence came from to the beginnings of animal evolution that start in the bottom of the ocean. He's joined today by my colleague Mary Miller. We'll start off with a quick summary of the book by Peter and then jump into the conversation. We hope you enjoy it.

- Thanks very much, Sam, and it's a pleasure to be here. The book "Metazoa" is an exploration of some largely philosophical questions about the relationship between minds, bodies, action, and life itself. And it takes the form, in part, of a tour through the animal kingdom, or at least one large part of the animal kingdom. The book's organized in a couple of ways, but one of the ways that's natural to organize a journey like this is by means of the tree of life, the tree of genealogical relationships between different kinds of forms of life on Earth, and in our case, particularly animals. So here, on the first image, we have one representation of the tree, where you should think of time as running up the screen, and evolution taking the form of a series of branching events, where one species gives rise to two, those diverge in turn, and soon you have many different kinds of forms of life, in this case, animal life, all living in their different ways, but all connected by relations of ancestry and descent in this tree-like structure. And in "Metazoa," we move through the tree, following different kinds of animals in turn and trying to use the way that each animal lives to teach us something about what it is to be an animal, what it is to have a mind, what it is to act in the world, what it is to have a sense of self, most broadly, what it is to experience our lives. Okay, on the image on one side, all the way along, we have sponges. And sponges aren't usually thought of as animals, but they are animals distantly related to us. So if you go far back enough in time, you find a common ancestor of you and a sponge. Sponges are special because they have the active features of life, of animal life, but they don't have a nervous system. And they have the ability to organize some of what they do, but with none of the sort of movement and more dramatic forms of activity that you would find in other animals. So sponges, and in the book in particular, deep sea glass sponges, mark our setting-off point. Now this image is not of glass sponges. They are much too deep for me to have come across them. These are sponges in Indonesia with a sort of barrel-like form, or as I like to think of them, forming a kind of choir, where water is coming in at the bottom of the animal, and food's being taken from it and coming out at the top. The next animal we encounter does have a nervous system. This is the crucial animal invention. So what would we see here is a soft coral. It looks like a flower, but it is an animal, and it can move like an animal, although at a very slow pace. So that flower-like structure there is a polyp, and if you watch closely, you can often see a sort of gentle opening and closing of those flower-like, petal-like fronds. And I think of this as an indicator of some of the earliest forms of animal action. So if we're trying to understand what action is and what animals do, it's this flower-like radially-organized pattern of behavior that we find, perhaps in some form very early on in animal evolution. So going back to the image there, we've now looked at sponges and corals. The next animal we come across behaves very differently. An encounter with some of these animals was one of the sort of formative experiences in this book. So these are banded shrimp. They are crustaceans, they live on reefs, and they have complicated little lives. Here we find a male and female pair. These animals are monogamous, long-lived, very territorial, and they live their lives in a small area with a lot of sort of face-to-face fussing of the males and females. And here we get to the stage in the history where we have recognizable forms of animal action. Now, one of the important things about these guys is, everything they do will have consequences for what they sense. Some of what they sense results from stuff happening outside, and some happens as a consequence of their own actions. So in animals like this, as action becomes sophisticated, and sensing becomes sophisticated in this way, you have to start to keep track of what you yourself are doing in order to filter out the consequences of your own actions, as opposed to external events, in interpreting what's going on in your experience. So I think of this as one of the real landmark stages in the evolution of animal action. They're very complicated creatures, quite beautiful, with this amazing array of appendages. They have those two large claws, they have four smaller claws, those antennae, they have legs, they have all sorts of stuff. These are arthropods, and this is very much the arthropod way of being, to have a great array of bizarre appendages attached to your body with which you probe and manipulate the world, and that kind of action, I think, is part of what gives rise to distinctively animal forms of sensing and consequently, experience. Moving further along the top of the tree there, so we're looking here all at present-day animals linked by these relations of ancestry and descent, we then reached the mollusks. And for me, an outstanding mollusk is of course the octopus. So here we have some video of an octopus in Nelson Bay, Australia on a kind of rampage. This animal is moving through the environment, foraging, basically, hunting, encountering all sorts of other things which have to deal with it as they go. That animal sort of hovering just above it is a seahorse. One of the pleasant surprises to me, while following some of these octopuses at Nelson Bay, is that seahorses seem to be allowed just to sort of cruise around alongside them in some cases. The octopus does a kind of bear hug around a soft coral, feeling for possible food, while again, the seahorse hovers, watching, Now, an octopus has a very different kind of sensing and action from the arthropods, the crustaceans that we looked at a moment ago. In an octopus, everything that is touched is tasted, and the nervous system is distributed through the body in a way that creates all kinds of unusual forms of selfhood, it seems, in these animals. In the middle of the book, I try to work out what kind of consequences this distributed organization, the active arms that taste everything they touch, might have for the experience of the animal. Here is that same octopus in more of a portrait shot. Then we reach our group, vertebrates, animals with backbones. And the animals that I follow at one stage in particular detail, which I do regard as just the most astoundingly beautiful creatures, are these whale sharks. So a whale shark is the largest fish in the sea. They get to about 40 feet long. This one is not as long as that, might be about 30 feet long. And in the motion that they engage in in the water, you see the kind of power of the vertebrate body. And they have a way of moving which has this amazing grace and power, with these huge bands of muscle controlling the enormous body. The vertebrate body was a kind of invention of a new kind, and one of the things I think about late in the book is what difference it makes to have a brain organized in the way that a vertebrate's brain is organized. So as a whale shark descends, and you watch it from above, you're watching this astounding product of marine evolution heading down into its home. After spending this time in the sea, we eventually make our way, as animals did, onto land. In the last part of the book, I start to think about what difference it made to animal evolution and to animal life and animal experience, becoming land-based rather than marine. Most of animal evolution, in its earlier stages, all the basics were laid down in the sea, but the land and our transition to land do have their own distinctive role in the story. Okay, I'll stop there and we can chat.

- Thanks, Peter, for that quick tour of your book. It's just such a pleasure talking with you. From reading both of your books, I know that you are a philosopher and you study the mind, but you're also an avid diver. When did you realize that you could better understand the nature of mind by going underwater?

- Right, that was a lucky event, and it wasn't something that I planned. And it seems a bit odd in retrospect, that I'd spent lots of time thinking about evolution in my philosophical, philosophy-of-science life, and also quite a lot of time thinking about animals and the mind, but there was no animal that I'd sort of taken as a subject of very close study. And the whole thing was a bit abstract. And then probably about 12 or 14 years ago now, I just began spending more time in the water when I was coming back from, during the American summer breaks, coming back to Australia a bit more regularly. And in the water, I began to encounter giant cuttlefish. They were the ones that started the thing. These are animals that, they're mollusks, so they're octopus relatives, but they're these large, incredibly colorful animals that also have a kind of engagement with divers, and with people in the water in some cases. And when I began to think about that combination of features, an animal that was so far from us in evolutionary terms, but had that apparent interest, that kind of engagement, and apparently so much going on inside it, I thought, right, I just have to look more closely at this. And that was the beginning of the whole process, from giant cuttlefish to octopuses. And then the point of this book, "Metazoa," is to be a little bit less obsessed with cephalopods and think about the animal kingdom more broadly, all the different kinds of bodies that there are, how they evolved, when they evolved, and what life might be like for many more of these kinds of animals.

- I mean, it's awfully easy to get obsessed with cephalopods. I am, too, very obsessed with them. In your book "Other Minds" you describe a cuttlefish that you encounter, and some of the amazing sort of color changes and skin pattern changes. Can you describe that experience and what you thought might be going through the mind of the cuttlefish? Because as you describe it, there's no other cuttlefish around. It just seemed to be emoting.

- Right, there was that particular one that I came across. It was at dusk, it was quite late in the day, and the animal seemed to be settling down into maybe not sleep, because it was sort of hovering, and still moving its body, but although there was no one around except me and this animal, and I was trying to keep back a bit, so as not to get too much into its space, it went through this astounding series of color and pattern changes that I think of as... I began to think of it as akin to a kind of, a bit like a sort of lucid dream or of a sort of half-awake dream. It also had to experience on my side, almost a kind of symphonic aspect. I felt like I was watching a lot of chords being produced, different colors in different parts of the animal. One of the mysteries to cephalopods is why they go through quite the intensity of color changes that they do in some cases. Their color change abilities were thought to have originally evolved for camouflage purposes, and then being pressed into service as forms of signaling in some cases, but in some animals like this one, you just have a lot more color being produced than seems to make any sense, given what's going on around them. These animals are also, officially, at least, supposed to be color-blind. They can't see all the detail, all the colors that they're producing. Now, I am suspicious about that particular claim on the biological side, but certainly, there seems to be a kind of outrunning on the expressive side of anything that has any immediate utility to the animal. And I find that just incredibly intriguing and charming.

- As a philosopher diver, your primary focus hasn't been on biology. You've had to learn an awful lot of biology, and about these animals, in order to consider this evolution of the mind, which is kind of what you're currently writing about. How did you do that? Did you do a lot of reading? Did you work with scientists? I think you describe some partnerships you have with scientists in order to understand what might be happening in the brains of these amazing cephalopods.

- It has been a kind of frantic process, especially in this book, "Metazoa." In the case of "Other Minds," which was mostly about cephalopods in particular, I could get to know what people knew about them reasonably quickly. And as you say, I had and have some great collaborators. David Scheel, who was also the subject of the documentary "The Octopus in My House" or "Making Contact," the one with Heidi, the dreaming octopus, he's been a very important collaborator for me over quite a few years now, and has guided me through how to take a more scientific perspective on these animals. Now, in the case of "Metazoa," which covers corals, jellyfish, crabs, insects, fish, many kinds of fish, and then eventually makes its way onto land to consider land-based animal life, it's been a frantic process of trying to sort of keep up with learning enough biology to write these things, as I explore experiences and interactions with the animals themselves. So I think frantic is the best word for the process of trying to learn enough. And I'm very indebted to all the collaborators who've guided me through my attempts to understand new animal groups, people like Andy Barron on the insect side, Culum Brown on the fish side, all sorts of people who've helped me understand their particular kinds of animals.

- I mean, I think what's so wonderful about reading your books is that you weave these experiences of observing animals underwater with this research you've done and the consideration about what could be going on in the experiences and the brains of these animals. And I just really, really enjoyed reading them. With octopus in particular, I think there's so much to talk about because as you said, they have a central brain, but they also have, their arms are packed with sensory suckers, as well as nerves. And I'm kind of having a hard time thinking about what's going on. I'm wondering if there's an analogy maybe in music. So I play the piano, and when I play a piece, I'm using my 10 fingers, but it's controlled through my brain. Is it like that, or is it more like a jazz director with eight musicians all improvising together? When you think about that octopus and how it operates, is there a metaphor in music that makes any sense to you?

- I think that jazz analogy is quite a good one, actually. You can imagine a relatively cohesive, and perhaps, unusually centrally-directed jazz ensemble, where there is someone in charge, perhaps even a conductor, but there's no attempt to control the details of what the players produce, in the way that there is in standard classical music, of, you know, 18th, 19th centuries, where everything is notated. You could imagine a situation where there's some centralization, there's a place the music is supposed to go, it's guided by a score, but every musician is free to produce embellishments, quirky explorations, wonderings. As I say this, I'm reminded of some concerts of John Zorn's ensemble that I went to some years ago. I think that might be an interesting particular analogy to a cephalopodic form of a musical organization. So I think that's a good analogy. It should also be added that we still don't really know what the relationship is between central control and peripheral control in the octopus body, the cephalopod body more generally, but the octopus is the especially fascinating case. We don't know to what extent the central brain can exert a top-down focused course of action on the parts or whether the central brain is really giving more general directions and leaving it up to the arms to sort of find their way through the general course of action that's being described. It's difficult to even make headway on that question. There are experiments still coming out. There was a nice recent one from Michael Kuba's lab, which, like other recent work, does seem to tell on the side of, you know, yes, the central octopus can bring things together when it wants to. And at other times, perhaps the arms are left to improvise.

- Well, I just think that octopuses have just sort of exploded into the scene lately, with, you described David Scheel's movie, which I saw and loved, where he had an octopus in his house, and the octopus seemed to develop a relationship with him and his daughter. And then there's also a recent movie, very popular on Netflix called "My Octopus Teacher," where a South African filmmaker goes down every day to the same patch of kelp forest and develops a relationship, what he considers a relationship, with the octopus. And I'm just wondering as a scientist, as you are, are we in a little bit of danger of anthropomorphizing these animals? I know you do try to think about their experience, but they are not humans.

- Right, right. I loved "My Octopus Teacher," by the way, I thought that was a wonderful film. It has some astounding footage in it. There is the risk of the wrong kind of anthropomorphizing. I agree with that. I see the situation as follows, for much of the 20th century, discussions of animal experience, animal minds, were guided by a kind of contrast between what was seen as a hard-headed mechanistic approach, where you attribute as little as possible to the animal by way of mental complexity, that is being the scientific way of doing things, and a perennial temptation of falling into a kind of romanticized, overly anthropomorphic view of the animals. Now, to set things up that way is to suppose that all of the errors will tend to lie on the side of over-attribution to the animals. And I think there's no reason to believe that. I think a more sensible attitude, and this is one that we're starting to see more commonly now, is one where it's possible to over-attribute mental complexity and experiential complexity to the animal. It's also probably possible to under-attribute it. It's possible to see the animals as more simple and mechanistic than they really are. Especially if you study animals only in a lab in very regimented circumstances, you could miss a lot of the richness that becomes present when you're out in the wild with them. So I think if the situation is one where it's reasonable and appropriate to try to imaginatively get inside the animals' heads, I don't think that's a illegitimate thing to do, to try to work out how the world seems to them, what experience is like for them, and to do that in a way that's sensitive to both the possible kinds of error, the error of thinking they're just like us, because as you say, they are definitely not just like us. That's one kind of error, sort of imputing human kinds of reflectiveness, human sorts of sensory organization, other human traits to the animals without good evidence. But it's also possible to miss a lot and to think that they are just simple little robots with a lot less going on inside them than there really is. So I think one just has to try to take a middle course and be sensitive to both both kinds of possible errors.

- But I think there's just something interesting. You talk about working with these animals in the lab or in sort of a captive setting, and I have friends that work at the Monterey Bay Aquarium, and they actually have to move them away from the cephalopod gallery because people get too attached to the animals, and there's a sense that when they walk in, the animals, the octopus look at them and recognize individual people-

- Right, right.

- And that they all have different personalities. Some are cranky, some are friendly. For a solitary animal, it just seems extraordinary that they seem to have that not kinship, but sort of recognition of us as individuals.

- It is, yes, and when talking about captivity versus the wild, octopuses are a wonderful, special case because I think moreso than most other animals, I think captivity is something that... Or the captive environment, the laboratory, or the aquarium environment, is something they come to regard as a special place that conditions their behaviors, and they come to recognize individual people, as you say. So there's been anecdotes on this front for many years, but a while ago, an experiment that was done by Roland Anderson and Jennifer Mather and their colleagues showed that it does look like, it does seem that octopuses can come to recognize individual people and react differently to them according to how the person has behaved towards them. I think that's real. As you say, at the end of your comments just now, it's one of the weirdest things about this situation, that all this complexity in cephalopods exist in an animal with such a short life. Octopuses are usually dead by the end of the two years of life or so. Some of them can live a bit longer. The giant Pacific octopuses that you often see in aquaria now can live a bit longer. But these are animals that really do rush through their lives. They pack a lot in there, but there's not much time for it all to happen. And when I came across that fact quite early in my exploration of cephalopod encounters, I was startled and upset, I must say. It seemed just terribly poignant to have an animal that had so much going on, but that didn't usually live beyond two years or so.

- So a lot of what we consider intelligent animals take a long time to grow up, like chimps. They have a mom, they learn from the mom, even sea otters, they learn from their mom. But octopus are solitary and they don't live very long. How is it possible that they pack so much learning experimentation and problem-solving into such a short life? It seems like that's why it makes a good model for understanding the mind.

- Well, it makes them a weird model for understanding the mind, a puzzling one. I mean, those two features that you just mentioned, the fact that octopuses are mostly rather solitary animals, and the fact that they're so short-lived, both of those are completely mysterious, when you think about it in a context of an animal with a large nervous system, lots of behavioral complexity. If you talk to a biologist about what it would normally be that makes it make sense for an animal to evolve a large nervous system, and all that cognitive complexity, it's often thought that social life is an important factor here. Usually for animals, the most complicated things they have to deal with are other animals, especially animals of their own species. And secondly, it would normally be thought that a long life is important, because if you're going to learn a lot of stuff about how the world works, you'd want some time to put that knowledge to use. If you are dead soon after learning what you've learned, you're not getting the payoff from the learning. Now, in the context of that general theoretical picture, octopuses are utterly mysterious. There may be some hidden social complexity in some species, but the general picture is still one of a rather solitary animal. So you have a very big nervous system and lots of complex behavior in a short-lived and mostly solitary animal. And there's no way around it. That's just quite a puzzling combination.

- So with a lot of reluctance, I'm going to leave the octopus aside for now, and move on a bit to your book, "Metazoa." You wrote that when you dive into the sea, you are diving into the origin of us all. And you talk about minds being evolutionary products. Can you elaborate a little bit more on the sort of building blocks? You talk about sensing and acting as the key to animals evolving brains, and that's kind of nerves and brains, are those the building blocks that you are considering as you talk about the evolution of the mind?

- Yes, basically, so in the book "Metazoa," one of the guiding ideas is that the formation of different kinds of action, different ways of acting, is a central and distinctive feature of animal evolution. So animals are specialists at acting, when compared to other kinds of life. It's not that you don't get behavior outside of animals. Even in single-celled organisms, there are various behaviors, but in an animal, you get action at a different spatial scale, the scale of these enormous objects, with countless billions and trillions of cells, all working together to get coherent action to arise. And the book "Metazoa" is partly a story about the history of animal action, especially as it relates to philosophical questions about minds and bodies, the mind-body relationship, and whether a materialist view of the situation makes sense. So that's the big picture. Now, one of the first things that one encounters, once you start to think about the history of action and the history of the senses that feed actions and make actions possible, and the nervous systems that control all this, one of the first things you encounter, which I think has been appreciated less than it might be, is that all the central input, all the central early stages took place in the sea. So the crucial period where many of the building blocks, as you'd call them, were laid down, is around the time of the Cambrian explosion, 540 million years or so ago, to some extent, a bit earlier, to some extent, a bit later, but around that general time. And this was a time when all animal life was still marine, it was all taking place in the sea. So the sea was the environment and the context for the evolution of eyes, of learning, of memory, of action. The arthropods such as the banded shrimp that I showed in my introduction, they occupy a special place in the history because there were probably arthropods, animals of that general kind, were probably the first animals to acquire the ability to move in complex ways and manipulate objects. And that, I think, is how the story is naturally told, about how the mind can have a place in the physical world, a place on Earth. It's a story that begins in the sea and essentially involves the evolution of different kinds of animal action and the sensing that feeds that action.

- So sensing, there's all kinds of ways that animals sense, but in an aquatic environment, you were just talking about the banded shrimp. The eye seems to be very critical for developing that complexity of motivated action. I'm wondering if you see a parallel between the evolution of the eye and the evolution of the brain. Because often in intelligent design, they say, "There's no way that an eye, a human eye, could come about by small steps. It has to be an intelligent creator, because it's too complex." But you know, obviously shrimp have a complex eye. Is there precursors to it, or do you think about how they develop together, the eye and the brain?

- Eyes do have a special role here. Vision has a special role here to some extent. There have been arguments in understanding that crucial episode, the Cambrian explosion, the period when animal bodies got more complex and behavior became more complex. A guy called Parker some years ago offered the hypothesis that it really was the evolution of the eye and vision, the ability to detect objects at a distance and react to them that set the whole process in train. Now that might be overstating the particular role of the eye itself; some people think so. But certainly, there was something like, and now I'm gonna use a terminology introduced by Roy Plotnik, there was a kind of Cambrian Informational Revolution around this time. Sensing became a lot more complicated, with vision as a special case. And animals began to encounter each other in new ways, especially as predator and prey, as competitors of various kinds, in real-time interaction rather than just the general way, the competition for resources is more or less inevitable in evolution. And I do think of that as a pivotal process. The eye, I mean, as you say, the intelligent design people sometimes have chosen the eye as an example of something so miraculously complex that it causes a conundrum for evolutionary theory itself. In a way, the opposite is true. The evolution of the eye is something that we have a good understanding of, with a lot of gradual steps, you know, a light-sensitive surface or a small light-sensitive patch, the folding in of the light-sensitive surface so there's some directional information when light comes in from different sides, the formation of the lens, the retina. There's roughly four main stages in the evolutionary process that got us to eyes like ours or that of the shrimp, but countless in-between cases. Between the four main stages, there's lots of sort of half and partial and intermediates. So eyes, they are uniquely important, perhaps, as forms of sensing, as mechanisms for sensing, but also, they have a well-understood gradualist evolutionary story.

- So I'm gonna kind of talk a little bit, have you talk a little bit about sentience, because I think that when we consider minds, and maybe some of us who have dogs or cats, sometimes there seems to be a point at which they're not doing anything, they're not chasing a squirrel or eating, they just seem to be kind of sitting there. And you might wonder what is possibly going through their minds. And especially, I think dreaming is one of those activities that it seems very obvious that there is something happening in there. The dog, you know, my dog, his paws will go and he'll be whining and almost barking, and I'm fairly certain that he's, in his head, chasing a squirrel. What role does this internal thought process have in trying to understand the brain or the evolution of the mind?

- Okay, how do we understand the relationship between the eye of the shrimp and the dream of a dog? There's such an enormous apparent gulf there. Right, I mean, let me first say, I agree that it just seems inescapable to think, when you watch a dog doing those things you were describing, it's very hard to believe that they're not dreaming in a sense that includes the experiential side of dreams. Now one might ask that, and then I think it's reasonable to be somewhat critical and say, "Well, is that just, is that an example of the kind of anthropomorphizing that we were talking about a little earlier?" How can we get a handle on the question of whether those episodes actually do have an experiential side? I try to have a go at this in the last chapter of the book "Metazoa," because I think there are some fragments of evidence that do support the idea that there's an experiential side to this. So one of the most interesting and fruitful recent areas in neuroscience has been the study of the memory systems in rats, especially how they deal with space, how they learn to navigate an environment, learn pathways to food in particular kinds of mazes and environments and so on. And the establishment of map-like structures in the brains of these animals. Now, a few years ago, it was discovered that not only do rats have map-like structures in their brains, but when they're asleep, sometimes the brain engages in sort of rehearsed and remembered pathways, through... You can look at the brain, what's going on, and see that the sequence of activation events in different parts of the brain corresponds to a pathway that the animal has taken, or in some cases, might take, in the physical environment itself. Now, one of the important things about this work is it gave a kind of functional rationale for certain kinds of dreams. Why would you have these internal events of this sort, rather than just resting while you're asleep? Well, it might be consolidating memories and also in some cases, plotting different possible courses of action, exploring possibilities for the future. Now that might sound like a lot to be going on in a rat, but there's fairly good evidence that something like that exploration of possible and not merely remembered paths is going on inside the brain of a rat when it's asleep. Now, why should we think that there's an experience side to that? Well, there's just fragments of evidence involving things like the way in which some of these events are undergone in the rat's brain very, very quickly, and others are gone through at a kind of natural pace that would correspond to the way that things occur in time during waking. There are fragments of evidence like that that do suggest that some of these episodes might be experienced. And that opens a picture in which you have... This is a sort of, in some ways, a coarse-grain distinction, but a distinction that can be expressed in terms of, there's online processing from the sensors to action with various stuff in between, and there's also offline processing. Where online processing is the kind of thing you're doing when you're awake, you're seeing things, you're responding to what you see, your actions reflect your sensory experience, and so on. There's a line from sensing to action, which is present and uninterrupted, and you're acting in real time as a consequence of experience. And that in some animals, at least, there's offline processing, where some of the processing is just disconnected from what's immediately sensed and also from any immediately-produced actions. And in humans, it seems, there's a family of these offline processes, including daydreaming, dreaming itself, mind wandering, all of which may have, among other functions, a kind of exploratory role, a turning over of possibilities. Now it might be natural to think at a certain point that, okay, there's online processing and that's what animals do. They sense, they act, they do stuff, they have to deal with other things around them. And then offline processing, the exploratory, freewheeling, daydreaming stuff is peculiar to humans. And there's work that suggests that that's not how it is. The work on rehearsing and remembering of possibilities during rats in sleep is probably the best example. There's also some less tight, less firm work on cephalopods, actually, cuttlefish, describing the possibility of dreamlike states in those animals, as well. So the general picture we're getting to, and this is going to tie the eye of the shrimp to the dream of the dog, at least in principle, is that one of the things you get as nervous systems become more sophisticated in an evolutionary process, not from shrimp to us, but from the ancestors of both of us down various lines, including to shrimp now, and to us now, one of the things you get on these historical evolutionary lines is the invention of offline processing, and in some cases, offline experience, the experience of the daydreaming, mind wandering, and dreaming itself, as in your dog.

- In "Metazoa," you explore what it means to be sentient, that many animals we take for granted can have complex experience and deserve more consideration than we often attribute to them. In a lot of indigenous cultures, they do attribute agency and soul to animals, and they have respect and gratitude for what the animal provide, whether it's food or knowledge. I'm wondering if there's something that Western science can learn by having this perspective. It seems to me that you do kinda come to this with honest sort of respect for the animals themselves.

- The word that I think is, the one I would pick up on as particularly important there is the word gratitude. I think that's really a good word to sum up the difference between the typical treatment of animals in industrialized Western societies, and the treatment of animals in a great many other cultures, indigenous cultures, earlier versions of our culture, all sorts of others. What's been lost, I think, in particular, is something like gratitude. I was discussing this exact matter just the other day with Olivia Judson, the science writer. We were trying to sort of think about the right way to describe the relationships that should and should not exist between us and animals. And the absence of gratitude, which was actually, I think, suggested by her, as in the case of your comment, I think it really captures what's particularly important here. So if there was something I would like to recover or at least, or reinvent, or get back to or reach in the future in societies like ours, it would be that sense of gratitude and what comes with it, a respect for the lives of animals, a sense that if we're gonna control them as much as we do, then we should control them in a way that has a strong sense of responsibility, that their lives should be worth living, that they shouldn't just be treated as objects to be grown as fat as possible with no regard for their welfare. So, right, that concept that you put on the table there, I think, is really the ideal one.

- And I also just really appreciate, and I find it really fascinating, to kind of flip it, flip the script a little bit, and just consider what the animals experience. There's a wonderful passage in a Barry Lopez book, "Of Wolves and Men," where he just spends the first part of a chapter describing a male wolf trotting through the forest, what it's sensing, what it's experiencing, what the other animals around it are doing. And it's just like, it just was a beautiful piece of science writing that I think just makes you much more empathetic or much more aware that human beings don't have everything to tell us about what the world is, you know, that by looking at animals carefully, as you do, that we can be humble and learn quite a lot. I get the feeling that you're not quite done exploring the evolution of the mind. Are you working on another book? Is there a continuation of this exploration?

- Yes, there'll be a third book, which will broaden things out even more. So if "Other Minds" was focused on cephalopods and "Metazoa" was broadening to much of the animal kingdom, not all of it, but lots of it, the third book will especially look at our part of the animal kingdom, primates and ourselves, what kinds of beings we humans are, considered evolutionarily. And the other part of the third book will be a direct investigation of the things we were just talking about there, which involve what's the proper relation... How might we properly think, or better think, about our relationships to various other kinds of animals, both wild and domestic, and also to sort of life on Earth as a whole, how we should think of our relationship to the whole, the whole ongoing project of life on Earth. So that will be the third. It will try to nail down, with a bit more tightness, the ideas about the nature of conscious experience that I feel I was getting a fair way along with in "Metazoa," but with all sorts of interesting loose ends left hanging. It'll try to cover that. It'll have a lot about us and our evolution, and it will think about those questions about how we should think about our relationship with life and the Earth in general.

- Well, that's something to look forward to. Maybe we'll visit with you again when that book is done.

- Sure, yeah, that would be great.

- I wanna thank you for the fascinating conversation today, and also giving me a whole new perspective. Next time I go diving, I'm gonna think about what a hermit crab or a shrimp is experiencing, when I'm underwater, so thank you so much, Peter.

- It's been a pleasure. Thank you.

- Well, thank you, Mary, and thank you, Peter, for coming and sharing your new work with us. If you're interested in purchasing a copy of "Metazoa," which was just released, you can do so at our store at exploratoriumstore.com. Thanks for watching After Dark Online. We'll be back next week looking at creativity. Thanks again, as usual, for learning with us. Have a great night.