Quirks and Quarks - Whales, sex, and rocks — it's our holiday book show!

Episode Date: December 19, 2025

We talk to authors of some of this year’s most fascinating science books in our annual Holiday Book Show.INCLUDING: Questioning the purpose of whale song — for love or echolocation?Journeying through deep geological time to better tackle problems of the futureBiological sex is complicated but that's what helps animals like humans thriveMini reviews of: The Martians by David Baron, Dinner With King Tut by Sam Kean and The Mind Electric by Pria Anand. 

I am an actor, fresh out of theater school with big dreams and an even bigger drug habit. But things are pretty good. That is until my best friend is set up on a date with David Lee Roth. Yeah, from Van Halen. If you know, you know. From CBC's personally, this is Discount Dave and the Fix. The true-ish story about how a fake rock star led me to a real trial that held up a mirror to me. And okay, let's just say that not everyone in this story is who you think they are.

Personally, discount Dave and the Fix. Available now on CBC Listen or wherever you get your podcasts. This is a CBC podcast. Hi, I'm Bob McDonald. Welcome to our Quarks and Quarks Holiday Book Show. This is generally a chaotic time of years, so we're hoping you can find some time to kick back and relax with a good book. And if not, well, at least we might be able to give you some inspiration for a last-minute gift,

or even for conversation fodder around the dinner table. Like, what if everything we thought we knew about whale song was wrong? So I think I was expecting something very melodic and bird song-like, but then when I actually heard, it was something like, and an anthropologist explores the complicated world of biological sex in the animal kingdom. In the blue-headed rass, you have one body, one set of DNA, and one, two, or even multiple voids. versions of which sex it is across its lifetime. That's pretty fascinating.

Plus, journeying through deep geological time to better tackle problems of the future. It's special to be able to see right inside the earth and be completely absent of any sort of plants or sun. It just gives you a real new perspective on the planet. All this today and more on the Quarks and Quarks Holiday Book Show. When Eduardo Mercado first heard a whale sing, he wasn't all that impressed. In fact, he first thought they sounded like cows that had eaten some bad grass. But it sparked a curiosity and led him to wonder what exactly are these whales saying to each other. The common theory was that the whales were singing to attract a mate.

But that didn't sit right with Dr. Mercado. So over the next several decades, he's become one of the world's top experts in whale songs, working tirelessly to figure out just what all their singing actually means. Now he's put his life's work into a new book called Why Whale Sing. Dr. Mercado is a professor of psychology at the University of Buffalo. Hello and welcome to our program. Thank you for having me. So first of all, tell me what happened when you first heard that whale singing.

So the first time I heard whale singing was on a recording made by others. So I didn't have the joy of being out in a boat and seeing the whale itself. And I had no preconceptions about what I was going to hear. So I think I was expecting something very melodic and maybe bird. song like, but then what I actually heard seemed like maybe the well was in pain. So I was kind of surprised by what I was hearing. Can you imitate what it sounded like? I'm not sure I can do justice to the full humpback well voice, but it's something like

you're right. It sounds like indigestion. Okay, break it down for me. What exactly constitutes a whale song? Sure. So well songs are not quite like a human song or bird song and they don't have to start and stop in the same way that songs that we listen to would be that are basically if you record the very large wells, the baleen wells, which include the humpback well. If you record them when they're singing, they'll keep on making sounds continuously for multiple hours in many cases. And if you monitor what they're doing, you'll realize that they're cycling through a fixed

sequence of patterns. And it's this sequence of patterns that's been described as being a humpback well song. But there's not a clear beginning or end. It's more like an acoustic carousel where they're always going around. the same order, but there's not really a beginning. But you arguing in your book that whales don't actually sing the way we humans think of the term. What do you mean by that? Right.

So historically, since the 1970s, when the humpback whales are first described as singing, researchers have believed that what whales are doing is essentially the same thing as what birds do when they sing, which is produce a performance that other animals can listen to and judge the quality of the singer. What I'm proposing in this book, which is what I've been proposing for a while, is that what scientists have been calling songs are actually a sophisticated form of echolocation, similar to what bats do, but over a much broader spatial scale, so that the whales aren't performing for other wells but are actually exploring to generate

their own essentially internal view of what's happening around them for many miles or kilometers. Well, before we explore that, why do other scientists think the songs are actually courtship rituals? Yeah, there's multiple reasons why people are. are convinced that that's what's happening. I would say the number one reason is that most humpback whales that have been sexed while singing were males. So there's this sexual difference.

They're often singing in context where breeding is happening. So it's definitely has something to do with sexual reproduction. And then just the complexity of it makes them think that it has to be some kind of display like a peacock's tail. So I think those are the three sort of major reasons why most biologists would say that humpback well song is like a bird song. So why didn't that idea resonate with you? Yeah, I mean, I didn't come into this trying to think of some new idea for what whales were doing.

I was just trying to understand what the beliefs were about it. And the analysis I was doing, I was analyzing the sounds within songs. And I noticed after analyzing songs from about a decade, it had been recorded before I'd ever started, that the sounds they were using were changing over time from year to year in a way that, such that if you've made an alphabet of the sounds they used in, say, 1992, that alphabet would no longer apply in 2000. And that seemed weird to me because no their mammals were doing that.

And birds definitely were not doing it. And so I didn't understand how wells could judge the quality. It's like a peacock tail that changes every year. And I didn't understand how this would be, you know, judgeable by other wells if it wasn't always something constant about it that would allow you to say this is the best kind of song you could produce. Okay. So what led you to believe that it could be sonar?

Right. that was the big sort of like aha moment, I think, because I just was confused about what would be possible. And I was studying dolphin echolocation at the time, and I read some studies of belugas, who when they echolocate, they typically do the normal dolphin eclocation by producing clicks and getting echoes back.

But if you have them echolocate things that are really far away from them, they switch to a different mode of eclocation, this little bursts of clicks. And when I saw that, I was like, oh, so if you're going to echolocate things that are very far away, you need to do something different from the norm. And then I thought, well, could the whales possibly be doing that? And then I started looking for additional evidence of animals who are exclating far away like

bats and discovered that they were doing things very similar to what the whales were doing in very similar contexts. So it was sort of like, I guess a hint and then looking to see like what the implications of that would be. And I did some experiments looking at the physics of it, whether it would be possible for a well to detect, say, another well that's two kilometers away, using their song, and it worked out physically. So it was sort of like I just got let into it.

Well, how did you study the whale's sonor abilities throughout your career? So there's multiple ways I've been attacking it. The first was just analyzing the sounds themselves to see, like I said, look at the physics of it, to see, well, if this is what the sound amplitude is, and this is the environment they're making the sound within, how far can the sound actually generate echoes? It would be useful. And then I kind of switched over to the more important part, I think, which is how can they interpret the echoes after they've gone so far, given that the sounds are changing.

And so a lot of my research over the last 20 years has been just seeing like how rapidly a brain can modify the way it responds to sounds, how easily can pick up on very small differences through repeated experiences. And so it's a combination of neuroscience, physics, and then just looking at the behavior that's been observed in the wild when they're making these sounds. Well, you did say that the whales are capable of producing sounds that are way above the range of what humans can do, or a bigger range, how far can the whale sounds travel underwater? Right.

So if you're talking about humpback wells, their sounds can easily travel 10 kilometers in most contexts where they sing. They can also be detected as far as 100 kilometers away. And if you're talking about other wells that sing, like a blue well or a fin well, their sounds have been detected as far as 1,000 kilometers away, which is pretty impressive for an animal.

Well, it is. But if they're echolocating that far away, what kind of information are they getting? Oh, but they're not echolocating that far away. So the current belief about why they're making the sound so loud is that they are trying to communicate other animals that are very far away. But what happens with echolocation is that when it hits an object, only part of the sound is reflected back. So if you produce an extremely loud sound, you're only getting a little bit of that energy back. So the loudness of the sound is not, I would say, to make it go really far, but it's to make the echoes detectable that aren't as far.

So it's a necessary ingredient for the echoes to be useful, and it's a side effect that you can detect it so far away. Okay. Well, tell me about your work to understand the cognitive skills of humpback whales. Yeah, so one thing that's different between the way I approach it versus most biologists is that they're interested in how the males and females decide who to choose sexual partners. And from my perspective, I'm more interested in sort of the spatial perceptual scenario. So what's happening inside the singer's head, which you can't directly observe, but you can study in other animals and get some sense about what's happening. And so I'm interested in how they can attend to things that they can't directly perceive because you have to imagine that a whale that's in the ocean, they sing day and night. And they cannot see more than probably 50 meters away from them. But most of the relevant things that are happening are way farther than 50 meters.

So they have to kind of like recreate the world in their head based on what they're hearing. they don't really can't really see that far. So it's a question of like, how do you deal with all the different sounds that are happening? How do you use that to reconstruct like a spatial map of the world around you? How do you deal with the fact that other animals may be doing the same thing at the same time so that you don't get confused about what's happening? And it ends up being, you know, sort of a problem solving task with the brain to figure out what's happening. And then for the whale to decide what do I do?

Because if it detects other wells moving around, you know, three kilometers away from them, they can't just swim straight towards them because they do. by the time they get there, that well's gone. So they have to kind of imagine, like, what's this well going to do next? If I want to join with that well, what I need to do, how fast we need to swim, what angle, etc. I mean, I should say that when the whales are singing there by themselves, almost always, they're not moving. So they're just kind of hanging there in the water.

But then when they actually swim off, they stop singing and usually swim off at a very directed manner. So it's clear that when they start swimming, they've decided the singing time's over, and I've got to go be in some position based on whatever they've learned from what they've experienced when they were listening. When you talk about the whale trying to recreate the environment around it, when it can't seem very far, it sounds like what I would do in the dark when I'm trying to figure out what's around me. How common do you think the cognitive abilities of the whale are to what we do?

I mean, in terms of their brain, they have all the same structures, more or less that we have, but they're not identical. So probably they have most of the same abilities like memory, thinking, attention, perception. We don't know that for sure, but the anatomy suggests that's true. But yeah, I think you're exactly right. It's like if you're in the dark feeling around, but if your arm was like two kilometers long, that would be the more equivalent scenario. Now, there is ongoing research by other people who are trying to decode the whale sounds and figure out what they're saying to each other. What do you think about that? Yeah, there's a lot of, especially now because of the emergence of a

large language models, so chat GPT and other AI systems. There's this push to try to use those to collect information about different whale species, a lot of work on sperm wells, some on dolphins, and a little bit on humpback wells, trying to figure out like what is the information being transmitted, which I think you can definitely learn things about what the varieties of sounds whales produce are like. I'm not necessarily convinced that that's the way to go, because Because the implication of, like, my hypothesis about what's happening with song is that it's not the sounds themselves that are important to the wells making them. It's the silences between the sounds where the echoes are coming back.

So they would actually be analyzing the wrong part of the signal from my perspective. Although those scientists think that they're on the right path. Yeah, well, every scientist thinks that what they're doing makes sense. And it takes a lot to convince them they're wrong. And from my perspective, I've seen a lot of the AI-based attempts to translate well sounds and dolphin-sense. sounds. I think they're definitely learning things from it, but I just feel like they need to consider all possibilities before locking into one. I mean, I think they should do both. I think they should analyze the sounds and the silences to see what's happening. I mean, maybe they'll

find that some of the sounds are being used specifically for transmitting information to other whales, and some of them are. So if you are convinced that the whales are using their songs, their sounds as echolocation to understand the environment around them. What in your mind are the whales actually seeing with their sound? Yeah, so my assumption is that based on my analyses of what the sounds are like, is that they're primarily focused on large targets that would be moving. So they could sense things like a human could about how deep the water is, things like that, but I think what they really care about is what other wells are doing.

And unlike dolphins, they don't spend their lives with specific individuals. They're kind of all nomads. And so they don't hang out with friends. They don't hang out with family. They're all kind of on their own. So the only way they can interact with the wells is to kind of keep track of what's happening. And they're not always in the same spot. They're migrating from like Antarctica or Alaska to some tropical island and back every single year. And they may not seem the same well twice in their lifetime. So I think like for them, it's a matter of keeping track of like here's what's happening around me, almost like a fisherman. Like if I see things that are happening that are relevant to me, then I'll engage in that. And if I'll engage in that. And if

they don't see anything, then I'll move on to somewhere else. So I think it's a kind of exploratory social scenario where the only way they can really monitor what other animals are doing that are located, you know, 10 kilometers away is to scan really broad sections of ocean and keep monitoring when new whales show up and when they leave. So what are you working on now? So right now I'm working to look at the situation that really only a few people have looked at so far with any balean well, which is when there are multiple wells seeing at the same time, they can all hear each other.

do they attend to the other well's songs and modify their own songs based on what they're hearing in real time, or do they just ignore each other? And so we're analyzing multiple wells singing simultaneously to see if you can detect interactions between them, and we actually have detected interactions. So we now know that when there's at least two wells that sing together, they're modifying their songs in ways that suggest that they're doing it based on what the other well is doing. So almost like a coordinated sound production, which people hadn't really observed before. So it is important communication then.

Well, it depends how you look at it. So, I mean, it's true. All the songs are communicative because they're revealing what the well is doing, where the whale's at. In that sense, yeah, there's definitely communication. But if it's two wells that are both singing together, they could be using it to kind of exchange messages to each other. But they could also be doing it kind of like two fishermen adjusting where they put their boats at or where they cast their lines based on the fact that there's another fisherman there. So they could be essentially focusing on a specific part of a space. like, I'm going to focus over here, you focus over there, and we're not going to try to

detect the same thing at the same time. Or maybe they would try to take the same space at the same time. So they may not be actively trying to exchange information with each other, but they may be sort of accommodating each other or at least adjusting what they do based on the fact there's another well there with kind of close to them. By the way, close to them means like, you know, three or four kilometers away. I don't want to sound like you. Yeah, exactly. Because if we're both doing the same thing at the same time, then our echoes are going to sound very similar, and it's going to be harder for us to tell who's echoes or who's. Dr. McCartle, thank you so much for your time.

Well, thank you for having me. Dr. Eduardo Mercado is a professor of psychology at the University of Buffalo. Now, we've got a couple more interviews with the authors of some fascinating books in our show this week, but we've also asked science journalist Dan Falk to tell us about some of his favorites from this past year. Dan keeps a close eye on popular science books in his podcast, Book Lab. Here's Dan's first review. In his latest book, veteran science writer Sam Keen turns his attention to archaeology, but with a twist. His new book is called Dinner with King Tut, how rogue archaeologists are recreating the sights, sounds,

smells, and tastes of lost civilizations. The way Kean sees it, traditional archaeology is too dry, too academic. To make the field more exciting, he embarks on a globe-spanning quest to not merely uncover facts about ancient cultures, but to live as those people lived. The book starts off in Africa 75,000 years ago, and finishes off in 16th century Mexico. Along the way, Kean learns how to flake stone tools, to bake bread the way the Egyptians did, and to craft a canoe like an ancient Polynesian. While the book is non-fiction, it does include a series of brief fictional

vignettes, kind of mini-chapters in which Kean imagines the lives of people who lived in those far-off times and places. I found dinner with King Tut to be a refreshing and fun take on human history. A little over four and a half

billion years ago, our planet coalesced from a section of the massive disk of dust and debris circling our proto-stens Sun that eventually gave rise to our solar system. That's where the story of Earth really begins. And geologists are decoding that story, line by line, like a poem, as it unfolds through the layers of rock that make up our planet. And the tale it tells is full of scenes of destruction and renewal, where change is the only constant. This is what science writer Laura Poppec wanted to dig into in her new

book called Strata, Stories from Deep Time. In the book, she takes the reader through four global geological transformations that made our lives on this rocky planet we call home possible, and how that kind of deep geological understanding could better help us prepare for problems in the future. Hello, Ms. Poppick. Welcome to our holiday book show. Thank you so much for having me, Bob. First of all, let's start right at the beginning. How far back in time can we look for rocky clues of what the early Earth might have looked like? So, yeah, that's a great question. And it's one that's constantly changing as people look deeper back into the rock record.

But I decided to start my book about halfway through its existence, around two and a half billion years, because that's the first time you get a real kind of reliable record of Earth. What was the first major transition in the rocks in Earth's history? There were so many different, obviously, changes and events happening throughout our history. But the event that I chose to focus on is the rise of oxygen in the atmosphere, which is an event that left a really distinctive set of characteristics and clues in the rock record that scientists have been looking at and debating for decades now. So before oxygen accumulated in the atmosphere, which we know thanks to the rock record, there was only single-celled life. So single-celled bacteria called cyanobacteria are thought to be the very first organisms that produced oxygen gas through photosynthesis. And so the story of oxygen's accumulation in the atmosphere is very much tied up in the evolution of this particular kind of bacteria.

You talk in your book about rock in South Africa that played a significant role in figuring out what gave rise to our oxygenated atmosphere. Tell me about that. Yeah, so the rocks in parts of South Africa are some of the oldest rocks in the world. So they're part of what's called a craton, which is a piece of the crust that just hasn't gotten sucked into the mantle as other pieces have. And so it preserves this really important window into this time when oxygen was first arriving in the atmosphere. And the researchers who I spoke to who study these rocks, they study long cores of rock that they've pulled out of the earth using something kind of like a large apple core that they can get hundreds of feet of continuous rock, which allows them to then go up kind of chronologically from the bottom. which is the oldest rock to the top, which is the newest rock, and kind of look for the transition from a world without oxygen to a world with oxygen.

And some of those clues are visible to the naked eye. You can see as you get into younger rock evidence of rusting. So you see more red-colored rock, which is, you know, rust is the result of oxygen interacting with metals. So you can say, oh, okay, well, maybe that's evidence of oxygen. However, old rocks can also become rusted, you know, long after they formed. So that's not always the most reliable clue of whether or not there was oxygen. How far back did these rocks go? So it's tricky with Earth history because you need a certain type of mineral to be able to precisely date the rock.

So they didn't find that particular mineral in this particular core. But they know based on measurements taken around the same rock type that this was roughly two and a half billion years old, give or take a few hundred million years. What other telltale signs did you see? So the question of how and when oxygen arrived in the atmosphere requires you to be able to see evidence of oxygen in the rock record, but you also need to see evidence of the absence of oxygen in the atmosphere. And you have to find that transition when the evidence that there wasn't oxygen goes away

and evidence that there is oxygen appears. And so both are important to the story. And the evidence that I found really beautiful for a time before there was oxygen is a sample that I found in a researcher's lab at Caltech, who's part of this group studying the South African rocks. And he showed me this sample of rock that has pyrite in it. So that's fool's gold. So it's kind of, you know, it has that kind of goldish hue. It's beautiful.

But rather than being a solid kind of sample that we think about in. museum gift shops and things like that. It was a disc that had been cut from a core that where I could see little grains of pyrite that had been rounded, almost like grains of sand. Like you could imagine that they had been pummeled in waves along some sort of maybe bed of a river or shore of some other body of water, which is not anything I've seen before in the world today. And I said that out loud to the researcher and said, huh, this is weird. Like I've never seen pirate like that before. And he's like, yeah, that tells you that the world was different back then. And I didn't know this, but he explained to me that the reason we don't see pirate as sand all over the

earth is because pirate dissolves in the presence of oxygen gas. So it would have entirely disintegrated if it had been somehow thrown into a river today. We would just not get that preserved in the rock record. But in a world without oxygen gas, it wouldn't have dissolved in the same way and it would have been able to be preserved. So how do we get from these first few cyanobacteria to an atmosphere with the amount of oxygen that we have today? It's a great question, and it's a source of heated debate. So the debate is whether all it took was for these bacteria to evolve and then to somehow proliferate and then, you know, over time, we get enough oxygen in the atmosphere. But the question is more complicated than that

because some people think that cyanobacteria evolved long before oxygen left its fingerprints in the rock record, but that oxygen, because it's such a reactive gas, in fact, it's one of the most reactive gases, materials on the planet, it would have gotten sucked into all different sorts of facets of the planet into other gases and minerals. It would have gotten completely taken in by these materials so that it could not accumulate in the atmosphere until something allowed it to. And that is the debate that I'd write about in my book, whether it's changes in tectonics of the planet, whether it's changes in nutrients available, whether it's some other thing. This is an area that people don't agree on, but that I find fascinating.

And when I asked one of the researchers, this person at Caltech, you know, why it matters, and his explanation was simply, like, if we figure this out about oxygen, how it arrived here, how it accumulated, then we understand how the earth works because it's this really fundamental gas that entirely changed the environment of the planet. And if we know how the planet responds to something so, reactive, then we understand something really fundamental about the planet and its capacity to change. Well, one of the things I enjoyed about your book is that you took me to different places, and one of the locations you took me to was down a mine where you were able to see the transition to before and after oxygen. What did you see there? What was that like? So this was an iron mine,

and it was a mine that was made possible from a time before oxygen. And we saved, that because kind of like pyrite grains of iron in the ocean entirely disintegrate in the presence of oxygen. And so there had for there to be the iron mines that exist today where the bulk of like the world steel is made from. So this is the material that is then put into the steel that kind of fuels our economy across the planet. For that iron to exist in such high quantities, there needed to have been a world where iron wouldn't have been dissolved on the seafloor, where it could just accumulate on the seafloor. So what I found when I went down into this mine was the result of there being an ocean without oxygen in it that allowed this iron to just build up

to the point that created this, you know, important source of this material that fuels our economy today. Well, you talk about how a miner drilled into some of this rock and it came out blood red. I mentioned earlier, you know, you can't always trust the rusty hue of a rock to tell you that it came from a time before or after auction because the rust can happen at any time. So I went down there, the walls were kind of rusty. But what happened was that a driller had kind of drilled in and the fresh rock is blue, but he's drilling in with some water squirting around the drill bit to clear it out. And that bluish rock is coming out like blood because it's been oxygen.

by the water. So what was happening? Yeah, so the fresh rock that was just beneath the surface was just being rusted and oxygenated by the water that was being kind of spewed into the hole. And so it's just evidence that these things are just constantly shifting before our eyes and we have to really know and understand how the minerals work to be able to read the rock record. Wow. What was that like to be down there and have that experience?

It was incredible. I wondered if I would be a little claustrophobic or kind of concerned that I was so deep in the earth, but it ended up feeling very comforting, actually. I wrote and I felt that it was like being in like a womb, like it was kind of moist, but not too moist, and it was musty, but not too musty. And it was quite comfortable, actually, and just gorgeous. So I, I mentioned that, you know, we have these iron formations that are swirling and beautiful and layered, but they're also just these pirate crystals that are kind of smattering the ceiling, almost like stars. So it was, it was gorgeous.

But you were also looking back in time to when the Earth was a very, very different place without oxygen in the atmosphere. Yeah, exactly. So it's special to be able to do that and to be able to see the inside of this place that we call home. We're so used to standing on the surface. Things are busy. Things are light. Things are growing. And then to see right inside the Earth and be completely absent of any sort of plants or sun, it just gives you a real new perspective on the planet.

Now, the rise of oxygen is just one of four major global transformations you cover in the book. How does the rise of oxygen set the stage for the geological transformations that came later? Yeah, so for life as we know it today to exist, we need there to be oxygen and we need there to be the type of photosynthesis that creates oxygen. I say that because there are actually other types of photosynthesis that organisms use to create energy from sunlight. they don't create oxygen. So this version eventually allowed the evolution of plants on land and for animals to follow these plants onto land and for the habitats that we know and love today to exist. And one kind of event that I write about is what the planet kind of underwent when plants first started growing up on land. And the evolution of these plants in some ways was tied up with the cyanobacteria.

So that is in some ways how that episode kind of set the stage for this later episode that happened much, much later, closer to, let's say, 400 million years ago,ish when plants were arriving on land. And now obviously oxygen is starting to increase as we have more plants growing, but we have other changes happening too, including the accumulation of mud on land, which is a really fun one for me. still, I love thinking about this time in Earth history where before plants kind of grew up on continents, continents were really mostly barren rock. And the idea is that there wasn't a lot of mud sticking around on the continents because there was nothing for that mud to stick to. So if there was a rainstorm that the clays and the silts that make up mud would just get flushed into rivers and dumped into the bottom of the ocean. And so it wasn't until plants started growing on continents that they provided a little bit of texture to land,

and then the mud particles could begin to stick and accumulate. And this had huge implications for the kind of evolution of landscapes on the planet. Rivers started flowing in different ways. You started having floodplains with muddy kind of substrates for plants to start growing further inland, and now all of a sudden you have the possibility for animals to follow those plants inland. And fast forward to the evolution of humans. I mean, a human civilization gathers on the banks of muddy rivers where plants have helped that mud stick. So it's all connected.

And that's what was so fun in writing this book was to see how all of these different episodes are connected over billions of years of time. So why is it important, especially as we look for solutions to our climate crisis, to understand these nuances in Earth's geological history? It provides us a look back at what the Earth has been through so that when we think about what might happen in the future, we don't have to go blindly wondering how the Earth responds to different changes. We can actually look to Earth's history to see how it has reacted to past changes in greenhouse gas levels, changes in temperature, how life has responded to those episodes. We don't have to go blind. And so we can learn the feedback loops and the ways that Earth has kind of evolved to balance itself out through these periods of change to get a better sense of what we might be able to do to kind of balance ourselves back out as we move forward. It's also in a really important set of context that provides us the insight we need to recognize how unusual the rate of change is now. And that's key is that you can look at Earth history and say,

Earth has always changed. So what does the change today matter if the earth has always changed and why it matters, obviously, for so many reasons. But what we point to is the rate that the change is happening at and that rate is far faster than rates of change in the past. And we know that thanks to the rock record. Ms. Poppick, thank you so much for your time. Thank you, Bob. This is a pleasure. Laura Poppick is a science writer based out of Portland, Maine, and the author of Strata, Stories from Deep Time. Now, here's science journalist and host of the book lab podcast, Dan Falk, with another review.

The human brain is like no other structure in the universe. It's 80 billion plus neurons, and their hundred trillion plus connections, make us who we are. But the brain is also a fragile organ, and when something goes wrong, reality can get turned upside down. For Priya Anand, a neurologist with a gift for storytelling, the brain's workings and its occasional failures reveal important truths about the human condition. Her book is titled The Mind Electric, a neurologist on the strangeness and wonder of our brains. With Anand as our guide, we witness all manner of unusual medical cases. We meet an epilepsy patient plagued by the same four cords from a vein.

Van Halen song, which keep repeating in her head. Another patient sees her son's t-shirt change color from red to green, then back to red. Another patient insists they've already died. A book like this could feel exploitative, but the mind electric doesn't. Instead, there's deep compassion on every page. And the result is a book that's hard to put down. The Mind Electric is a terrific read. I am an actor, fresh out of theater school with big dreams and an even bigger drug habit. But things are pretty good. That is until my best friend is set up on a date with David Lee Roth. Yeah, from Van Halen.

If you know, you know. From CBC's personally, this is Discount Dave in the Fix. The true-ish story about how a fake rock star led me to a real trial that held up a mirror to me. And okay, let's just say that not everyone in this story is who you. think they are personally discount dave and the fix available now on cbc listen or wherever you get your podcasts bickering why can't a woman be more like a man i beg your pardon yes why can't a woman be more like a man men are so honest so thoroughly square eternally noble historically fair but when you win we'll always give you a back a pat why can't a woman

Be like that. That song from the film My Fair Lady is a classic for many reasons, one of them being how it plays off some of the more old-fashioned views of men and women at the time. While it may be convenient and easy to categorize life forms on Earth as being either male or female, with clear definitions of each, in reality, biological sex is complex, with a lot more overlap and variability than we ever imagined. Which is why in a new book, primatologist and anthropologist Augustine Fuentes

wanted to explore the biological continuum of sex across the animal kingdom, and what that reveals about the messy world of human sexuality. Dr. Fuentes is a professor of anthropology at Princeton University and the author of Sex is a Spectrum, the biological limits of the binary. Hello and welcome to our holiday book show. Thanks, Bob.

I'm glad to be here. Well, let's start out with the basic definition. How do you define sex? That is a great question. So most people, when they think of sex, they think male and female, right? So usually they think reproduction of some sort. Sometimes, as in many biologists, they think, well, it's whether you make a big gamete, the ova or what we call an egg, or the small gamete, the sperm.

But we can also think about sex in the sense of how our bodies work and how we sense our bodies, how masculine or feminine we are. All those kinds of things come into the sort of spectrum of sex. And so how we define this is going to be dependent on what kinds of questions we're asking. But the easy thing is to say, hey, look, sexually reproducing species tend to have two sexes. And those two sexes are what we're interested in. But you make a distinction between sex and gender. Absolutely. And so I think this is really important.

So I make a distinction when I talk about sex biology. So I'm really interested in all the biological things, all the things of our bodies and other organisms' bodies that are related to reproduction or that aren't related to reproduction but have connections to the systems, the biological and physiological systems related to reproduction. So that's what I call sex biology. Gender is a human thing. Gender is the social roles, their expectations, the identities, the social and cultural realities of living in different kinds of bodies.

And in reality, humans have sex and gender that's mixed together all the time. Well, let's go back to the very beginning. I mean, life began on earth with a single-celled organism that reproduces by just splitting itself in two. So I want to ask you a question you pose at the beginning of your book. If sexual reproduction is more difficult and riskier than asexual reproduction, why did it even evolve? I love that question. I mean, the simple answer is that, well, sex is fun, right? But sex is also really difficult.

Most people think that evolved for reproduction to create new life. In fact, sex evolved as a way to mix things up. Because for the first billion years or so of life on this planet, reproduction was asexual, right? Just divided internally and then made a copy of herself. But what sex does is it creates variation. And variation is the sort of heart of evolutionary possibilities. It is without variation, it's hard to evolve, almost impossible.

With some kind of biological variation, we have flexibility in a given population or a given species. So when we're challenged, if there's some genetic or other variables, variation within that species, their chances of overcoming those challenges are greater. So sex evolved to create variation. Mix up the gene pool, in other words. Yeah, mix up the gene pool, mix up bodies, mix up possibilities. So sex you can think of biologically offers a kind of hope, right, a kind of possibilities for meeting challenges you haven't even encountered yet. Now, you have all kinds of wonderful examples in your book of how insects reproduce. They have a lot of variety in their techniques. Let's look at a couple of them. Honeybees. Tell me about those.

So honeybees are amazing. And I think the way you said this, varieties of how insects reproduce. I love that because when we talk about sex, anyone who researches sex, one of the most common things you see is enormous variation in how animals do this. We're not even going to talk about plants. Plants are crazy. They do sex all sorts of ways. Let's stick with animals. But even animals, honeybees are amazing because they have two genetic systems and three kinds of bodies. There's two different kinds of female and one kind of male, but they're radically different in what they look like, in how they act, and what they do. So there's the queen, right? And then there's the sort of workers.

And then there's those few males that sit around for when the queen needs to copulate with them and propagate the species. What's really amazing about this is that honeybees have three totally different ways of being in the world that come from only two different genetics. and that are really interesting and flexible and don't fall neatly into sort of a binary male-female division. Wow. You also mention a type of fish that despite starting their lives as female can also become male. Yeah. How does that work? So I think this is amazing. This is actually not uncommon in the teleost fishes, what we call the bony fishes. What they're called this sort of sequential hermaphrodites is the official term. But what happens is, for example, in the blue-headed rass, a really nice little reef fish. All blue-headed rasses are born. And then when they mature, all of them mature into what we call the large gamete producing. They produce eggs or ova. So they become female. All the

blue-headed rass become female. Except as their bodies grow, the biggest one, in any given, there's a little group of these blue-headed rass living on a coral leaf somewhere. The biggest one, their body undergoes some kind of change. Their physiology actually restructured itself to become a male. unless another blue-headed rass from outside their group shows up who happens to be bigger, a bigger body, and so that that one who just became a male will switch back to becoming a female because the other one coming in is a male. The bottom line here is that in the blue-headed rass, you have one body, one set of DNA, and one, two, or even multiple versions of which sex it is across its lifetime.

That's pretty fascinating. Like I said, these are just different systems for dealing with the complexities and the challenges. of different ecologies and environments with sex biology. And the reason I go through all of these different insects and fish and earthworms and all these different fascinating organisms is to point out that sex biology matters, right? Whether you produce big gametes, eggs, or small gametes sperm, really matters to your body and to your life,

but that those things aren't some giant binary fixed in the world in only one way. There's lots of ways to be male or female or both. Okay, so that's fish. let's switch to mammals. What kind of sexual variation do we see in them? So generally mammals are considered some of the most stringent, right? The most strict for reproductive biology because, right, we gestate, right? Mammals gestate and then lactate. And that's a pretty complicated system. So in mammals, on average, there's a division

between those who have sort of a uterus and ovaries and those who have testes and no uterus, and they produce different kinds of gametes and have slightly different lives and bodies, depending on which species. But it's not always that clear. That's our general pattern. For example, the European mole female has ovaries, but also a lot of testicular tissue in her ovaries. So after she gets pregnant and gives birth, her ovaries start to shut down and the sort of testicular, the testes tissues in those ovaries, starts to turn on and change her hormone profile. where she becomes super aggressive mom and a crazy digger to make new space for the boroughs. Well, what about sexual preference? I mean, aside from reproduction, how much variation is there in other animals? So one of the things I remember, so I've spent a lot of my career looking at humans, but also looking at primates. And so I used to take students into the field to study macaque monkeys.

And every time I would take a bunch of students in, after this third or fourth or fifth day of observations, the students would come back to me, they're like, oh, I don't know how to score. this one observation. I'm like, what are you talking about? And what they were seeing was that there was a lot of homosexual activity, that is, sexual activity between females or sexual activity between males. And what they were pointing out and what the scientists took a while to catch up with is that same-sex behavior, social-sexual interactions is a central part of many, many mammals' lives. And so that's another interesting thing about sex and variation. That is, the acts of sex. Sexual activity is not just about reproduction. In fact, for many species, more sex happens outside of reproduction than inside

reproduction. Well, you talk in your book about how this binary view, male-female, is a limited way to see the world, and you say that humans are biocultural. What do you mean by that? Well, let me be very clear what I mean by a binary view, right? Think of this. A binary is like a one and a zero, right? There is nothing that overlaps between a one to zero. That's why we can use the binary system to write code, right? Because it's either a one or a zero. Animals, humans especially, are not like that, right? We don't have two types of human. We don't have two types of animal. We've got variations on biological form that have typical patterns and clusters, right? So males and females are these typical clustering with a lot of overlap and some individuals that don't

fall into either of those clusters. When it comes to human, we're not just talking about our biology. We're always talking about our biology that's been shaped, that interacts with, our cultural experiences, our families, our lives, our histories, all of those things. So humans are biocultural. Let me give you a very simple example. If most people listening to this took off their shoes right now, and they look down at their right foot, they would see the pinky toe, that fifth toe on the outside there sort of scrunched in under their fourth toe, right? Squenched under that. People always wonder, what is the point of that pinky toe? Why is it there? And what I would say to them is that you are looking, your foot is a biocultural object. That foot, that pinky toe scrunched under those other toes, that comes from you living,

you wearing shoes your entire life. You've reformatted the bones, the ligaments, and the muscles of your foot into a particular shape that is a cultural shape. And if you had grown up, not wearing shoes at all, your feet would look very different. Wow. So you're talking about nature nurture here. Yeah. Yeah, but I would say, and I've said this many times before, it's not nature nurture.

It's nature nurtural. It's a horrible word. And I made it up years ago and it didn't stick. But the point is that it's always a mix between the two. Like how you taste food, right, is built on your taste buds, but also the taste buds exposure over time to different foods and also the cultural things around you, what foods you've been given, what your parents like, what your friends like, all of those kinds of things. So your actual sense of taste, your sense of smell, all of those things are.

co-constructed from your bodies, your biologies, and your social lives and your experiences. So that's why we're biocultural. And if you think about sex and gender, I mean, you really can't get much more biocultural than that. How do societal expectations and the roles we take on play into the sexual and gender spectrum between males and females? Oh, that is about a 15-week podcast. Okay, well, let's do the short form. Let's do the short one. Yeah. I mean, think about it.

Culture is extremely powerful. And there are some patterns in gender across many cultures, but there's a lot of variations. So I like to think of masculinity and femininity, right? What do we expect from certain bodies? So when you think about that, we have very strong expectations of what a little boy and a little girl should be like. So strong, in fact, we dress them differently.

We sort of give them different opportunities for sports. We even feed them differently. And that's really interesting because we're bioculture, remember. So when you sort of treat someone differently, when you give them different opportunities, when they use their bodies differently, they mature in slightly different ways. And so it's hard to tell. Clearly, there are differences between males and females. That's really important.

But because our gendered expectations are so powerful in shaping how we interact, even with babies, it's not always clear how much of these adult differences or pubertal differences are biological and how much are cultural. Let me give you one example. So it turns out through a bunch of observational studies done, I think in Canada, in the United States and in the UK, they looked at people playing with infants in that sort of bouncing up and down way and found that people were more vigorous with little boys and softer with little girls. And in fact, they dropped little boys at a much higher frequency than they dropped little girls. Who knows what kind of impact that has.

But it is interesting that even at the level of interacting with infants, we speak to them differently, we talk to them differently. And so bodies are shaped by our cultures and our lives. I also notice this time of year when you go into the toy sections of large stores, you go over to what's for girls and all the colors are reds and pinks. And you go over into the boys' stores and it's army green or gray. I mean, even the colors are different. It is fascinating too. And that varies by culture.

But I think you're exactly right. As people are buying presents for their children, we also have to think those presents aren't just some cultural imposition. Oh, here's a girl present. here's a boy present, but they actually train the children to use their hands differently, to use their eyes differently, to use their bodies differently. And that's actually really fascinating. I'm not saying that's bad.

I'm just saying we have to recognize it because when we see some pretty massive differences in gendered identities and behaviors in adults or, you know, late teens, we can't assume those just come from hormonal changes that happen at puberty. Well, you do mention in your book about how hormones bathing our brains can change. depending on the role we take in the family. Absolutely. I think this is fascinating. First of all, let me be very, very clear.

Hormones are extremely important, right? For all life, but for mammals and particularly humans, right, are patterns of hormones. And all humans have the same hormones. We just have different levels and patterns of hormones, depending on whether or not we have testes or ovaries or different other aspects of our body. But I think what's really amazing is people don't realize

that all humans are incredibly wired to take care, especially take care of men, but to take care of one another as well. And it turns out if you do a lot of caretaking, so this is the work of Lee Gettler and other scholars, if you do as a man a lot of caretaking, especially of your own offspring, your hormone patterns are going to change, right?

Your body's actually going to change just because you're interacting and caretaking. So then think in a society which considers it feminine to caretake and not masculine, what does that do to bodies? That actually changes the ways in which bodies can work. What message would you like readers to take from your book, Sex is a Spectrum, especially during these politically challenging times? Look, it's difficult, right?

There are difficult times. A lot of people are afraid. A lot of people are confused. One of the most important things we can do is to continue to talk about this. But to talk about this, we have to have a baseline. We have to know how do bodies vary, right? How do cultures vary? How do humans vary?

That variation has to be our starting point. And at the same time, we really have to recognize that there's a lot of ways in which humans are successfully human, right? We're not all the same. And I think having knowledge, having empathy, and a little bit of compassion for people is going to go a very long way. Dr. Puentes, thank you so much for your time. It's been my pleasure. Dr. Augustine Fuentes is a professor of anthropology at Princeton University and the author of Sex is a Spectrum, the Biological Limits of the Binary. And to wind up today's special episode, here's science journalist Dan Falk again with one more book review. There's something about the planet Mars that tugs at the imagination.

Science writer David Barron is fascinated by the particular interest that Earthlings took in the red planet around the year 1900. His new book is called The Martians, the true story of an alien craze that captured turn-of-the-century America. At the center is the American astronomer Percival Lowell, who would end up founding the Lowell Observatory in Flagstaff, Arizona. When Lowell gazed at Mars through his state-of-the-art telescope, he saw, or at least thought he saw, an elaborate network of canals. As Barron tells it, Lowell had no intention to deceive. He really believed he was witnessing some sort of vast engineering project on Mars. But other astronomers never seemed to see what Lowell said he saw, and even as telescopes got bigger and better, those canals never seemed to get any clearer. Eventually, the idea of Martian canals simply faded away.

But the Mars mania that Lowell sparked would linger for decades, even influencing the young Carl Sagan a half century later. David Barron's The Martians brings to life a peculiar and fascinating episode in the history of astronomy. For Quirks and Quarks, I'm Dan Falk. Thanks, Dan Falk, is a science journalist and co-host of The Book Lab podcast. And that's it for our holiday science book special. You can find links to all the titles on our website at cbc.ca.ca slash quirks. You can also read my latest blog or listen to our audio archives. You can follow our podcast, get us on SiriusXM, or download the CBC Listen

app. It's free from the App Store or Google Play. If you'd like to get in touch with us, our email is Quarks at CBC.ca. Quarks and Quarks is produced by Rosie Fernandez and Amanda Buckowitz. Our senior producer is Jim Lebbins, and our acting senior producer is Sonia Biting. I'm Bob McDonald, and happy new year. For more CBC podcasts, go to cBC.ca slash podcasts.