From the Vault: The Wallace Line, Part 1

0:06Speaker 1:Hey, welcome to Stuff to Blow Your Mind. My name is Robert Lamb. Today is Saturday, so I have a vault episode for you. This one originally published 8-19-2025. It is going to be The Wallace Line, Part 1. Let's do it.

0:22Speaker 2:Welcome to Stuff to Blow Your Mind, a production of iHeartRadio.

0:32Speaker 1:Hey, welcome to Stuff to Blow Your Mind. My name is Robert Lamb.

0:35Speaker 2:And I am Joe McCormick.

0:37Speaker 1:And as I mentioned in at least a couple of previous episodes of the show, over the summer this year, 2025, my family traveled to Indonesia for some snorkeling. And in learning all about the local environment of Raja Ampat, the guides kept mentioning an individual by the name of Alfred Russell Wallace, as well as the faunal boundary named in his honor, the Wallace Line. In fact, I would say that Wallace was invoked one way or another, nearly as much as Darwin was invoked on my visit to the Galapagos Islands a couple of years prior. So, yeah, Wallace, the Wallace line, I mentioned a lot in terms of just describing what was happening in the natural world around us and in Indonesia at large.

1:20Speaker 2:That's a funny comparison because, of course, if you know one thing about Alfred Russell Wallace... It is probably that he was the other guy to come up with a version of the theory of evolution by natural selection around the same time that Darwin did. Though Darwin tends to get most of the credit. And I think in many ways, people understand Darwin to have articulated a more rigorous form of it. Wallace essentially had the same idea around the same time.

1:48Speaker 1:And to be clear, they knew each other. And in fact, Alfred Russell Wallace, you know, greatly looked up to Charles Darwin, and they were on friendly terms their entire life, even though they disagreed on some key issues here and there.

2:03Speaker 2:Yeah, well, actually, the version of the book that I was reading, so it's Wallace's book, The Malay Archipelago, where he's writing about his travels and observations in that region of the world. The edition of that book that I was reading is actually dedicated to Charles Darwin. He says, To Charles Darwin and author of The Origin of Species, I dedicate this book not only as a token of personal esteem and friendship, but also to express my deep admiration for his genius and his works. So it's elaborate.

2:32Speaker 2:It seems like no hard feelings there.

2:35Speaker 1:Right, right. It's also been pointed out that they knew what each other were up to around the same time. And Wallace's work and Wallace's ideas kind of poked Darwin and got him to sort of realize, oh, I really need to push Darwin forward with on the origin of species and maybe not focus on other projects at this very moment.

2:55Speaker 2:Stop collecting beetles, write the book.

2:58Speaker 1:Yes. So we'll be talking more about Alfred Russell Wallace here shortly. Uh, but as for the Wallace line, uh, I'm going to go ahead and throw out the short answer of what this is and we'll get into it more, uh, later in this episode and in the next episode. But basically, uh, it represents the place, um, between the Indonesian islands of Bali and Lombok, where the Australian and Asian faunas separate. So it separates the Indonesian archipelago between the parts influenced by Asian fauna and the parts influenced by Australian fauna. So, you know, rhinos, elephants, tigers on one side, kangaroos, monitor lizards, and koalas on the other.

3:37Speaker 2:Yes, exactly. With some caveats that we will discuss as we move on throughout the series.

3:43Speaker 1:So let's talk a bit about Alfred Russell Wallace here. You can look up images of the man, illustrations and photographs. He was, of course, a 19th century naturalist, explorer, traveler, academic writer, and totally looked the part, you know, English beardy guy who's out there in the wild exploring things or, you know, back at home in his study writing about them.

4:07Speaker 2:I was almost going to say if Darwin is almond joy. Wallace looks like mounds. He just looks like a kind of like, I don't know, a less crunchy version of Darwin. Kind of a softer, smoother texture.

4:19Speaker 1:Yeah, you could definitely say that. And it holds up in many ways. But in other ways, as we'll discuss, Alfred Russell Wallace was kind of the almond joy to Darwin's mounds.

4:29Speaker 2:Okay.

4:30Speaker 1:So, yeah, Alfred Russell Wallace lived 1823 through 1913. So long lived. And a fascinating individual. Multiple books have come out in recent years about him. But the one that I was mainly looking at is Radical by Nature, The Revolutionary Life of Alfred Russell Wallace. And this is by James T. Costa. Came out in 2023. And as the author points out, yeah, he was like a lot of people. He was a complicated individual. And there were certainly some seeming contradictions in the way he made sense of the world, the natural world. humanity's place in the cosmos and so forth.

5:09Speaker 1:So I'm going to break into a little bit of his biography here. I'm not going to go into super detail, but I'm going to try and hit some of, I think maybe the key points to getting like an overall understanding of who this guy was and, and, uh, some of the more interesting aspects of his life and certainly those contradictions. So he was born to a middle-class Scotch English family, a family on his father's side claimed to have an ancestral connection to 13th century, uh, noted individual William Wallace, the Braveheart guy, for those of you relying on cinema for your history.

5:43Speaker 2:For fans of accurate history, yeah.

5:46Speaker 1:But yes, claimed to be descended from William Wallace, whether that's true or not, who knows. But he initially worked as a surveyor, but remained vitally interested in many aspects of the world. So he was interested in botany and He had all these other natural history pursuits that he was leaning into. And at the same time, he was also attending talks about socialism, about spiritualism. He was also interested by mesmerism.

6:13Speaker 2:The practices of Franz Mesmer, also known as the theory of animal magnetism, not given any credit today. Yeah, yeah, definitely.

6:22Speaker 1:But also gets into sort of the whole hypnosis sphere of things for sure. On top of this, he taught, he lectured, and of course he read. He was familiar with the writings of the time of Alexander von Humboldt, of Charles Darwin, and many others. And in part due to their inspiration, he decided that he too would go out and see the world as a naturalist explorer.

6:48Speaker 2:That's right, because, of course, Darwin became famous for his writings about the voyage of the Beagle long before he actually published on the origin of species. Before he had a theory of evolution, he just had his travelogue of observations going around the world on a ship called the Beagle.

7:04Speaker 1:Yeah, so that seems to very much be the blueprint that Wallace has selected for his own life as well. And so he departs on a journey to South America, particularly focused on the Amazon. And he and his team there, they're studying the peoples of these areas, the natural history of this region. And then on the return trip, their boat catches fire and they're stuck in a life raft for, I believe, 10 days and then eventually rescued. So he apparently lost all of his notes in this adventure, this part of the adventure anyway, but he was still able to write multiple papers about it when he got back to England and Also, I believe that a number of specimens that he'd collected had been shipped back ahead of time.

7:46Speaker 1:So not everything was lost, but a lot was lost on that ship. But he wasn't quite done with traveling and exploring, which may come as a shock because I don't know. I think a lot of us might think that once your ship has burned and you've wound up in the lifeboat for 10 days, you might have had enough, but not so for Wallace.

8:04Speaker 2:I'm going to read later in this episode from a chapter in the Malay Archipelago where he's talking about his experiences in Bali and Lombok. But he is not above complaining about the hardships he faces on his journeys and the difficulties he has in doing his work. But it is still admirable that he can just face that kind of thing and move right on.

8:25Speaker 1:Yeah, and in a way admirable that you can still... be irritated by the little stuff later on, you know, after having wound up in the lifeboat for 10 days to still be able to say, ah, this desk is the worst.

8:37Speaker 2:We're going to get some epic complaints about it's hard to do science when everything is covered in ants.

8:43Speaker 1:Oh, good goodness.

8:44Speaker 2:I bet it.

8:44Speaker 1:I bet that is true. So anyway, he was not done traveling. And after he'd gotten back and he'd published a bit about his travels, he soon became fascinated with the Malay archipelago or the Indo-Australian archipelago, consisting of what is now Indonesia and neighboring nations, also known as the East Indies at the time. His subsequent travels in this region lasted from 1854 to 1862, so eight years. And during this time, he and his hired team collected thousands upon thousands of specimens. to return home and go to various museums and institutions. I read a BBC article pointed out that the number here was something like 125,660 natural history specimens, including more than 83,000 beetles.

9:44Speaker 2:So the majority of it was beetles. Yeah, it's just a lot of beetles. Well over half.

9:50Speaker 1:I mean, also, it seems like the beetles would be relatively easy to send back there. Yeah, It's a lot easier to send back a beetle as opposed to, say, a Komodo dragon.

9:58Speaker 2:That's true. And once again, we're going to revisit why it was so hard sometimes to send things back.

10:04Speaker 1:And of course, he wrote about his travels as well. And this is when he wrote the 1869 book, The Malay Archipelago. This is the book you were talking about earlier, a book that would go on to become an international bestseller. describing all the islands he visited, the sorts of natural and human elements on each, a little bit of griping about the ants and the deaths. But this is a book that resonated with people within his profession and within academia, but also outside of those boundaries. It was just a book that a lot of people read, and it kind of made him a celebrity. It cemented his status and also ensured that he was able to keep going and keep writing later on, certainly after a few economic setbacks that he encountered.

10:52Speaker 2:I found it captivating. While we were preparing to record this episode, I started reading a couple of chapters from this book, mainly because I was looking for Wallace to describe a scientific theory that we're going to get into. And I ended up not finding really any succinct place where he does describe this theory, but I was just sucked into the writing because it's so interesting and so good. And he in many ways reminds me of his contemporary Darwin in that regard, who also, I think, and this, of course, doesn't diminish from the validity of his theory, but also just like Darwin's books are a great read.

11:30Speaker 2:They're like they're very well written. And I would say Wallace's are, too.

11:33Speaker 1:Yeah, yeah, yeah. The Malay Archipelago, volumes one and two, the subtitle here being The Land of the Orangutan and the Bird of Paradise, a narrative of travel with sketches of man and nature.

11:47Speaker 2:Oh, well, Rob, since he mentions the orangutan in the title, you should scroll down in the outline because I included a screen capture of the page opposite the title page in the 1890 edition I was reading, which has an illustration of a brutal orangutan attack where the orangutan is jumping on a guy and biting a chunk out of his arm. I'm skeptical this happens that much in nature.

12:16Speaker 1:Yeah, that's generally not the reputation they have today. It's so weird, though. This was the second time today I've had to think about the possibility of a killer orangutan because, as many of you are aware, the actor Terrence Stamp died, I believe, over the weekend recently passed. And so there was some chatter here and there about his past movies. And I was looking around and I realized he was in a 1986 film called Link that is about a super intelligent... malicious chimpanzee, but the chimpanzee is played by an orangutan.

12:49Speaker 2:Oh, okay. I thought you were going in a totally different direction. I saw the headline that Terrence Stamp had died, which, you know, kneel before Zod. And I don't mean any disrespect here, but I truly thought you were going to say he died in an orangutan attack.

13:02Speaker 1:No, goodness. No, no, but yeah, this illustration from the book definitely made me think of that. But it also has a rather sweet image of an orangutan here.

13:12Speaker 2:Yeah, it's both, yeah. But from what I understand, orangutans, it's not that they can't attack humans. I think they're known generally to only do this when like really threatened in some way. They're not generally aggressive.

13:25Speaker 1:One thing we know from the interaction between humans and animals is that if the animals can be provoked into attacking humans, we will have done it at some point or another.

13:36Speaker 2:Yeah. But though, of course, some animals are much easier to provoke than others. And orangutans are not usually thought to be on the super high end of provocability. However, this illustration is sick.

13:46Speaker 1:Yeah, bites him right on the arm. But yeah, in this book, though, this is where he does get in a bit into the idea of the Wallace line. Now, he didn't call it the Wallace line. I believe Darwin's bulldog, Thomas Henry Huxley, called it that in his honor. But he does get into the concept a little bit.

14:06Speaker 2:Huxley also proposed some modifications to Wallace's original placement of the lines.

14:13Speaker 1:Now we get into the details in a bit, but basically the way that Costa describes it in his book is it was the realization that there was a growing realization, quote, a growing awareness among naturalists that anomalous patterns of distribution might provide unique insights into the history of the planet, geologically and climatologically. So again, this was This was happening with Wallace, but this was happening in other parts of the world with naturalists looking at distribution data and saying, hmm, well, this is interesting. We have X going on here, Y going on here. What does this tell us about how the world works, about how species have moved around or been moved around, about some of the barriers and potential barriers to their movement.

15:01Speaker 2:And so forth? Yeah, and about the abiotic history of the planet, like the fact that the distribution of animals as you find them today can tell you things about the history of climate change on the planet, about ice ages and sea levels, and even about underlying geologic activity, such as plate tectonics, which would not be, you know, fully accepted as a theory, I think, until 1960s or so, much, much later.

15:28Speaker 1:So we mentioned the fact that he independently came up with the concept of evolution by natural selection around the same time as Darwin, and then Darwin kind of pushes ahead and gets... on the origin of species out. In some ways, Wallace was also an early environmentalist in his voice concern over humanity's impact on the planet. And he also engaged in a number of social activism causes during his life, including women's suffrage, land nationalization, and various sort of pacifist and anti-militarism causes. But in an area that might seem rather contradictory to all of these scientific pursuits, he was also a spiritualist. And not just one in his non-academic life, not just like, okay, I'm, you know, scientific, academic, a naturalist by day and a spiritualist by night. No, he actively wrote on it and attempted to defend it in academic writings.

16:24Speaker 2:Now, to clarify, in the context of these 19th century movements, when we say a spiritualist, that doesn't mean the same thing as like somebody who would say, oh, I'm spiritual today. That would This means something more specific about like beliefs that you could contact the dead or that you could, that living persons could have communication with spirits or other beings other than living humans.

16:47Speaker 1:Yeah, we're talking about, specifically here, we're talking about the sort of spiritualists that you would go to and there'd be a seance or there would, you know, offer generally for money to help you connect with the spirits of the dead. The kind of people that Houdini did not like Uh, the kind of, uh, people, if you're, if you watch the gilded age on television, the most recent season has, uh, has included this element in its plot.

17:11Speaker 2:Yeah. It's come up on the show before that actually a surprising number of people from history and, um, In 19th century Europe and America, people who are in many ways kind of admirable for their time really got into spiritualism, really thought you could talk to the dead.

17:27Speaker 1:Sir Arthur Conan Doyle is a prime example of this, really got into it late in life. So, you know, it's one of those things where there are multiple pieces to it, as I think we've probably discussed in the past. On one level, you do have people actively selling you this stuff. And on the other, you have people a genuine desire on the part of the bereaved to connect with the people they miss. And, you know, there's in a perfect world, there's probably a balance there between the two where no one's exploited and everyone's life is made a little easier, but we don't live in such a world.

18:05Speaker 1:And so things will often lean in the wrong direction there. But again, not just a naturalist by day and a spiritualist by night. Like I say, he wrote papers where he defended spiritualism and so forth. Yeah. Now, on the other hand, he opposed flat earth pseudoscience of the day and wrote against that. And then going back to the other side of things, he did involve himself in anti-vaccination efforts of the day. This would have been, I believe, measles, the vaccine that he was opposed to. But in his opposition seems to have been a mix of like sort of personal choice, like I don't want to take it.

18:41Speaker 1:that we see similar attitudes today, but also it seemed to factor into his view that nature was perfectly balanced already, and therefore there was no reason to tip the scales as far as diseases go. I don't know. I would say that the counterargument to that is that as far as diseases and humanity go, that everything is already out of balance, and therefore you need the vaccines in place. Well, yeah.

19:04Speaker 2:I mean, a lot of the times people prefer one course of action over another because it's more natural. It just kind of reflects a vague and not very well thought out understanding of what the concept natural really means. I mean, there are a lot of things that just kind of seem natural to you, but then you investigate them and realize they're actually very much the product of human intervention in some way. Yeah.

19:27Speaker 1:Plus extinction is natural. It doesn't mean I want it for myself. Yeah.

19:30Speaker 2:It is natural to just like all get disease and die.

19:33Speaker 1:Sure.

19:34Speaker 2:I mean, is that good? Yeah.

19:37Speaker 1:So yeah, he was an interesting guy in this. His spiritualism especially did put him at odds with many of his fellow scientists. And even when it came to evolution by natural selection, he argued for a kind of evolution driven by the divine, essentially that animals evolve via natural selection and humans did to a point, and then some other force takes over. Something divine, he didn't actually call it a creator because interestingly enough, he himself was a religious skeptic. So he at different times self-identified as agnostic or just a non-religious person. And so he referred to this as an overruling intelligence.

20:20Speaker 2:It's interesting how if you go back just a hundred years or so, you get a lot of fine distinctions in religious beliefs where the distinctions don't make a lot of sense to people today, but they made sense to people at the time.

20:34Speaker 1:Yeah, yeah. He was a firm believer that He thought without this overruling intelligence becoming involved, there's no way that the human brain or human speech organs or even our hands or our bipedal posture could have possibly evolved. There had to be some other force, like a monolith, getting involved in our advancement. Yeah. And, you know, that's kind of a sticky idea. That's why we see it all over our science fiction, right? Yeah, yeah.

21:02Speaker 2:And, you know, it's still a common idea. I mean, this is formally argued by creationists today, but I mean, it's still, it's naturally appealing to look at something very complex and think, well, that couldn't have just happened. Of course, I think that the leap that you're not able to make there is that it happened gradually and by degrees.

21:22Speaker 1:Yeah, yeah. And, you know, I often think about this. I think that, okay, you know, a much, softened version of this is maybe quite reasonable in a quite reasonable way to balance science and religious faith. You know, say, well, okay, evolution by natural selection is the method by which the divine creates life. And why not? Because it seems like the very sort of elaborate, long-term method that an eternal and all-powerful entity, unconstrained by time, might very well employ.

21:50Speaker 2:Sure. I mean, I think that's what millions of people believe today.

21:53Speaker 1:Yeah.

21:53Speaker 2:Nothing wrong with that.

21:55Speaker 1:Yeah. On the other hand, it is worth stressing that when you get into the particulars of this sort of stance saying, well, OK, everything evolves, but then humans evolve differently. Human brains are different because of some divine force. You can get into some. really nasty and even racist views on human evolution by deciding just where and how you want to deploy this theory. Ah, yeah.

22:17Speaker 2:Okay. So appealing to supernatural forces to inject a certain specialness into, you know, certain, you know, animals on earth. And certainly there's nothing that prevents somebody from thinking that some humans are more special than others.

22:31Speaker 1:Right, right. So I'm not saying that was Wallace's whole deal, but those are kind of, those are the waters you can easily creep into by pursuing this line of thinking.

22:38Speaker 2:Yeah.

22:39Speaker 1:Now, with Wallace, it certainly put him at odds with many of his fellow scientists, including Charles Darwin himself, who worried that Wallace was hurting their cause by adding this caveat to his own take on natural selection. And according to Costa, he even wrote to him and said, quote, I hope you have not murdered too completely your own and my child, referring to the theory of natural selection. Again, these two points, were friends and, um, and, and, uh, Wallace, you know, continued to respect Darwin the rest of his life. Uh, but yeah, Darwin rather bluntly saying, uh, I really wish you hadn't put it like that, you know, trying to get this theory of natural selection out the door and accept it at this point. And you're perhaps muddying the waters by coming in with this, uh, you know, your unique spiritualist take on everything. Yeah.

23:31Speaker 2:Though, I guess one thing that's supposed to be good about being friends is that you can be Frank with each other.

23:35Speaker 1:Yeah. But yeah, Wallace seems to have been a guy who, as I think Costa puts it at one point, he had a lot of adventures and a lot of opinions in his life. He was real quick to weigh in on things. And well into his 80s, he was still doing this. I mean, I think until the end of his life, pretty much constantly writing letters, writing his own take on different topics. And in fact, in 1904, he put out the book, Man's Place in the Universe. And in that, he takes his own serious look at the idea of life on other planets, especially Mars, because this, of course, is the time when we have the whole canals of Mars idea out there in everyone's minds. You know, the idea that we've seen things on Mars and what if they're canals and we get this built up idea of their people of some sort on Mars and they're a dying race and they're having to build these canals and so forth. It really captivated everyone's imagination.

24:35Speaker 2:We've talked about that at some length on episodes in the past, and now I don't remember which ones. Did that possibly come up in our discussion of the ashen light of Venus?

24:47Speaker 1:It might have, yes.

24:48Speaker 2:That's my best guess.

24:50Speaker 1:So this was a 1904 book, and I have not read it, but Costa gives his own breakdown of it and points out that, okay, he's basically opposing the idea of life on Mars on two levels. On one level, He is making a very logic-based counter-argument. He himself was an astronomer, and he's pointing out things about what was known about Mars versus Earth at the time. He just did not think it was likely that this was true. And of course, as we would find out very shortly thereafter, it wasn't true. But as Costa points out, it also ran opposite to his belief that humans had a privileged place in the cosmos, that we were The end result of not only earthly processes, but also cosmic processes as well.

25:33Speaker 1:This getting into the whole idea of humans were special because some sort of force beyond us had pushed us into these like upper levels of evolution that were denied to other, you know, or other organic life forms on Earth.

25:48Speaker 2:So the overruling intelligence of Wallace's view of the universe would not have allowed life on Mars.

25:54Speaker 1:Right, right. The whole idea is that we're alone and we're special. If we've got life next door as well, then that just destroys the whole argument. So that seems like it might have also been there, you know, pushing his criticism of this idea. Though, to be clear, this book, he's also apparently very polite in his takedown of the Martian Canal incident. Because he, you know, he's ultimately, you know, friends or at least correspondents with everyone that's talking about it at the time.

26:25Speaker 2:Boy, I'm sorry if I misunderstood. Did he also have like observation based or empirical reasons for doubting canals on Mars? Yes.

26:34Speaker 1:It wasn't just based in his worldview, but no doubt that worldview was also pushing him to make all of these arguments, you know.

26:42Speaker 2:Okay. So he was right, but for some of the right and some of the wrong reasons.

26:47Speaker 1:Yeah, that seems to be the take on it. But again, I haven't actually read the book in question. So again, that's just a brief overview of the man here. I think it highlights some of the inherent contradictions that are present there that ultimately are going to be present in anybody. But maybe you're a little more expressed in the biography of Alfred Russell Wallace. Yeah.

27:17Speaker 2:Very interesting character. And so I guess now should we move on to talking a bit about the Wallace line, at least what the concept is? And then I think maybe in part two, we'll get into some more depth about it, nuances that have been added to it since the time of Wallace.

27:33Speaker 1:Yeah.

27:34Speaker 2:All right. So we alluded to this earlier, but to recenter us here, in addition to independently discovering a version of the theory of evolution by natural selection, again, around the same time Darwin did, Alfred Russell Wallace is also widely considered the founder of a field now known as biogeography, the study of how life is distributed over the surface of the earth. Another way to put it is what lives where and why. By the way, you mentioned him earlier, but another important contributor to the early study of biogeography was the pre-Darwinian German naturalist, Alexander von Humboldt. Very interesting figure who we've talked about a good bit on the show before. I think one of the main contexts was in a summer reading episode we did years ago where I was talking about a great biography of him by Andrea Wolff called The Invention of Nature. Von Humboldt was important in helping to move the burgeoning natural sciences of the 19th century away from this long-held Western view of nature as a fixed order of discrete entities with eternal roles defined by providence, and to replace that with a

28:44Speaker 2:view of nature as a complex and changeable web of relationships, these interdependencies that are constantly in flux. Though unlike Darwin and Wallace, von Humboldt himself never fully embraced the idea that species themselves could evolve. His idea of change was more based on the environment and relationships between species. So Darwin and Wallace ended up going beyond von Humboldt. But anyway, as I said, biogeography is the study of what lives where and why. And one of Wallace's most famous observations in biogeography is the Wallace line. The Wallace line is what's known as a biogeographical boundary line, specifically a faunal boundary in this case, meaning a boundary with reference to animals.

29:31Speaker 2:So it's an invisible border where you have one ecosystem of animal species on one side of the line and a very different collection of animals. on the other. Animal populations are not usually divided by hard boundaries. Normally, as you wander toward the edge of an animal's population range, you will notice a gradual thinning out of the population with the number of individuals becoming less and less dense, sometimes being replaced more and more gradually with examples of different species in the same trophic niche, meaning they compete for the same food resources. So you may be moving out of the range of one animal species and into the range of another gradually, gradually in both cases. For the most part, the geographic range of an animal species does not end in a hard boundary, but in a soft and gradual one. But there are exceptions. Sometimes you kind of hit a wall where there is one set of animals over here and a pretty different set over there.

30:36Speaker 2:And that is to a large extent what we find with Wallace's line, though, as we'll discuss, there are some exceptions to this rule and some major nuances added since Wallace first proposed this border in in the 1860s. In fact, basically all biogeographical boundaries are somewhat permeable. You will find exceptions to them, but they tend to denote starker divisions in biodiversity than you will find elsewhere in nature. And so what's the story of the Wallace Line in particular? Well, the Wallace Line passes invisibly through the islands of the Malay archipelago in the strait between Borneo and Sulawesi, And then further southwest through the Lesser Sunda Islands, cutting between the islands of Bali on the west and Lombok on the east.

31:26Speaker 1:While we were in Indonesia, we were east of the Wallace Line, though we had to fly over it to get to Raja Ambat from Jakarta. I will stress, though, the pilot did not announce the crossing of the Wallace Line. Not that they had to, but I just want to make it neat. Of course, you can't see it from the plane.

31:43Speaker 2:Yeah, exactly. And there's nothing there to see. In fact, it's kind of, it's remarkable how invisible it is in a way. So I was speaking of the division between these multiple land masses, Borneo and Sulawesi and Lombok and Bali. The latter division is probably the most striking because the Lombok Strait, which passes between Lombok and Bali, is in some places only a few dozen kilometers wide. Like if the air is clear, you can stand on the shore of one island and look across and see the other island.

32:17Speaker 2:You see the higher elevations on the other island. So they're very close. And in terms of environmental conditions, they're very similar. And yet, when Alfred Russell Wallace studied the land animals and the birds of these islands, he noticed a pretty stark difference. Wallace writes about some of these observations in the book, The Malay Archipelago, again, first published in 1869. So the version of this book I was looking at is a scan of the 1890 edition. That's the one with the sick illustration of the orangutan biting the guy. And Wallace writes that the islands of Bali and Lombok are most interesting actually because of two things.

32:59Speaker 2:One of them is that he claims that They're the only two islands of the whole archipelago in which the Hindu religion still maintains itself. And then he also says, quote, they form the extreme points of the two great zoological divisions of the eastern hemisphere. For although so similar in external appearance and in all physical features, they differ greatly in their natural productions. So what's the difference in these natural productions between the two islands? Again, while there are exceptions and some nuances we'll discuss later, the range of a ton of major animal groups essentially terminates at this tiny ocean gap. On the eastern side, in Lombok, you will find native cockatoos and marsupials, the animals associated with Australia and New Guinea. And on the western side of the gap, in Bali and Borneo, you will not find those animals, not natively, unless you find some imported Instead, you will find mostly the same animal groups that you find in the rest of Asia, including, at least as of a few hundred years ago, before many of these animals were driven extinct, you would find tigers, rhinos, elephants,

34:13Speaker 2:and bears. So you've got one on one side, one on the other, and then you've got, of course, some more transitional areas like We'll talk more in part two, I think, about the idea of a whole group of islands known as Wallacea that are thought of now as a kind of transitional island group. But on the island of Sulawesi, you will also find more of a mix with some native Australian or Australasian fauna and some Asian fauna. Now, the question of why is really interesting, and that's something we're going to have to come back to. But first, I just wanted to get some more color on Wallace himself and his travels in in these islands, specifically his chapter in the Malay Archipelago on his visits to Bali and Lombok. He makes an interesting biographical note that his first visit to these islands in 1856 was, quote, somewhat involuntary.

35:05Speaker 2:He was trying to get a ship to take him to Makassar on Sulawesi from Singapore, but he couldn't for some reason, and his journey got diverted to these islands at the east end of Java. And he writes that if he had been able to get the passage he wanted from Singapore, he probably never would have gone to them, quote, and should have missed some of the most important discoveries of my whole expedition to the East.

35:32Speaker 1:So just pure travel mishaps playing into, again, the most important discoveries of his career.

35:38Speaker 2:So, Robert, are you cool if I read some passages from Wallace here?

35:41Speaker 1:Yeah, let's have it.

35:42Speaker 2:Okay, this will give us a flavor of his writing and some of his experiences in Bali and Lombok, both those that inform... the formulation of the idea of the Wallace line, and also just some interesting stuff he comes across. So first of all, there's a passage where he's describing the terraced agriculture of Bali, where he says, he says, quote, a slightly undulating plain extends from the seacoast about 10 or 12 miles inland, where it is bounded by a fine range of wooded and cultivated hills, houses and villages marked out by dense clumps of coconut palms and tamarind and other fruit trees, are dotted about in every direction, while between them extend luxuriant rice grounds, watered by an elaborate system of irrigation that would be the pride of the best cultivated parts of Europe. The whole surface of the country is divided into irregular patches, following the undulations of the ground, from many acres to a few perches in extent, each of which is itself perfectly level, but stands a few inches or several feet above or below those adjacent to it. Every one of those patches can be flooded or drained at will by means of a

36:52Speaker 2:system of ditches and small channels into which are diverted the whole of streams that descend from the mountains. Every patch now bore crops in various stages of growth, some almost ready for cutting, and all in the most flourishing condition and of the most exquisite green tints. Oh, that's nice.

37:10Speaker 1:I would say succulent, even.

37:12Speaker 2:Yeah, I found his writing style very vivid. It really calls pictures to the mind in a way that a lot of older writing, especially, you don't quite get that immediate connection to the visual imagination. Something about Wallace's style does for me.

37:29Speaker 1:Yeah, there's a sense of awe here as well.

37:31Speaker 2:Yeah. But anyway, from here, Wallace goes on to describe his attempts to collect a few specimens in Bali. So he says... In so well-cultivated a country, it was not to be expected that I could do much in natural history. Kind of makes sense, right? Like it's harder to collect specimens from all of this well-kept farmland. Yeah, from the farmland, yeah. And my ignorance of how important a locality this was for the elucidation of geographical distribution of animals caused me to neglect obtaining some specimens, which I never met with again.

38:08Speaker 2:One of these was a weaver bird with a bright yellow head, which built its bottle-shaped nests by dozens on some trees near the beach. It was the Plosius hypoxanthus, a native of Java, and here at the extreme limits of its range westerly. I shot and preserved specimens of a wagtail thrush, an oriole, and some starlings, all species found in Java, and some of them peculiar to that island. I also obtained some beautiful butterflies, richly marked with black and orange on a white ground, and which were the most abundant insects in the country lanes. Among these was a new species, which I have named Pieris tamar. Okay, so that's his experience in Bali. He doesn't collect a lot of specimens because he doesn't know how significant this place is going to be. And he got here by accident anyway, didn't even expect to go here, notices a few things. But it's all the Western fauna. It's all the same kind of stuff you would see in Java, the same kind of stuff you would see grouped with other animal species generally in Asia. But then he moves on in his ship to Lombok. And he notes, by the way, that traversing the strait, sometimes the weather or

39:20Speaker 2:the chop in the strait can be pretty rough. And there's a story of him pulling all of his things ashore and being very grateful to get all of his specimens and bags and stuff on shore. And the locals tell him, oh, it's good that you did. The sea is hungry and it takes everything it can eat.

39:39Speaker 1:Oh, the South Sea Queen, perhaps.

39:42Speaker 2:Yes, though I was thinking of his loss of all of his previous stuff from the other boat. But yeah, so he moves on to Lombok and here he notes finding bird species that are not like the bird species on the other island. They are more similar to those found in Australia and New Guinea. He writes, quote, The country around was pretty and novel to me, consisting of abrupt volcanic hills enclosing flat valleys or open plains. The hills were covered with a dense scrubby bush of bamboos and prickly trees and shrubs. The plains were adorned with hundreds of noble palm trees, and in many places with a luxuriant shrubby vegetation. Birds were plentiful and very interesting, and I now saw for the first time many Australian forms that are quite absent from the islands westward. Small white cockatoos were abundant, and their loud screams, conspicuous white color, and pretty yellow crests rendered them a very important feature in the landscape. This is the most westerly point on the globe where any of the family are to be found.

40:47Speaker 2:Some small honeysuckers of the genus Telotus and the strange mound maker Megapodius guldii are also here, first met on the traveler's journey eastward. The Megapodius birds, by the way, these are these, you may have read about these before, these mound builder birds that are native to Australia and New Guinea. where they will build mounds. He describes, actually, in a passage, the locals telling him about how they build mounds out of anything they can get, garbage or whatever, and the locals know what to look for in one of these mounds to know when there will be eggs in it that are good for snatching. In fact, I'll just read a passage from Wallace. He says, The mounds are to be met with here and there in dense thickets and are great puzzles to strangers who cannot understand who can possibly have heaped together cartloads of rubbish in such out-of-the-way places. And when they inquire of the natives, they are but little wiser, for it almost always appears to them the wildest romance to be told that it is done all by birds. Excuse me, that it is all done by birds, but that does sound like the

41:57Speaker 2:wildest romance.

41:58Speaker 1:Yeah.

41:59Speaker 2:Now, here I want to come to the part where Wallace describes the difficulties of the physical part of his work, collecting and preserving specimens. I've alluded to this several times, but this passage really gripped me. So Wallace says, quote, Ants swarmed in nearly every part of it, and dogs, cats, and fowls entered it at pleasure. Besides this, it was the parlor and reception room of my host, and I was obliged to consult his convenience, and that of the numerous guests who visited us. My principal piece of furniture was a box, which served me as a dining table, a seat when skinning birds, and as the receptacle of the birds when skinned and dried. To keep them free from ants, we borrowed with some difficulty an old bench, the four legs of which, being placed in coconut shells filled with water, kept us tolerably free from these pests.

43:10Speaker 2:The box and the bench were, however, literally the only places where anything could be put away, and they were generally well-occupied by two insect boxes and about a hundred bird skins in the process of drying. It may therefore be easily conceived that when anything bulky or out of the common way was collected, the question, where is it to be put, was rather a difficult one to answer. All animal substances, moreover, require some time to dry thoroughly, emit a very disagreeable odor while doing so, and are particularly attractive to ants, flies, dogs, rats, cats, and other vermin, calling for especial cautions and constant supervision, which under the circumstances above described were impossible. Oh, man, I was getting so stressed just reading that, trying to think where to put the bird skin, where to put the dead whatever I just found. Where can it go that it's not just going to be swarmed with ants? And the whole time you've got ants everywhere, and it's all stinking because you're skinning it and then hiding it in a box that's the only other thing in the room with you.

44:15Speaker 1:And all manner of scavengers are... coming in to peek in and see what's going on with your dead animals. Yeah, it seems like quite an experience. And also, Wallace, quite a house guest to have staying as well, right?

44:33Speaker 2:I mean, one thing he notes, at least the parts I was reading, is he makes a special note of the hospitality he encounters everywhere he goes. It seems like He just keeps running into very nice, very helpful, accommodating people. And he's like, I was received very, you know, with all this graciousness and all that. So I just get the feeling from reading that he's a nice guest to have. He's very appreciative, you know, very polite, I think. Probably, at least.

45:00Speaker 1:Yeah, skins a lot of birds, collects a lot of beetles, but a nice guy.

45:05Speaker 2:Does stink up your house really bad. And there are already ants, but he probably attracts way, way more. Yes, this is actually something I almost always find interesting in reading books about science history is just the practical physical annoyances and problems with trying to do the core work, the core physical work of your discipline, whether that's collecting specimens and preparing them to be preserved. or doing experiments or whatever, you know, there are always little like problems like this where it's like, I can't do it because this thing doesn't fit right. Or I don't have the kind of table I need or, you know, or there's ants on everything. By the way, if you if you work in any area of research out there and you want to write into the show about your experiences of this kind, please do contact at stuff to blow your mind dot com. I always find these things interesting. Yeah.

45:57Speaker 1:Tell us about your fieldwork.

45:59Speaker 2:What is your Wallace's Room full of ants?

46:12Speaker 1:All right.

46:12Speaker 2:Can I flag one more thing from this chapter by Wallace about a boundary of sorts, but not a faunal one?

46:19Speaker 1:Yeah, I know what you're going to cover here. And this is an interesting one that I was reading about in my book as well.

46:25Speaker 2:Yeah, okay. So Wallace, by the way, he's about to refer to somebody named Manuel. Manuel is one of his local guides. So this is a guy he's been working with and has good relations with. But he says, a Bornean Malay who had been for many years resident here said to Manuel, one thing is strange in this country, the scarcity of ghosts. How so? Asked Manuel. Why, you know, said the Malay. That in our countries, to the westward, if a man dies or is killed, we dare not pass near the place at night, for all sorts of noises are heard, which show that ghosts are about. But here there are numbers of men killed, and their bodies lie unburied in the fields and by the roadside, and yet you can walk by them at night and never hear or see anything at all, which is not the case in our country, as you know very well. Certainly I do, said Manuel. And so it was settled that ghosts were very scarce, if not altogether unknown, in Lombok.

47:26Speaker 2:And then Wallace goes on to make a comment that I didn't know how to take at first, but I initially read this as maybe some kind of dry humor. But he follows this up by saying, I would observe, however, that as the evidence is purely negative, we should be wanting in scientific caution if we accepted this fact as sufficiently well-established. that sounded like a kind of humorous understatement to me, but now Rob, now that we've talked about his interest in spiritualism, that assessment actually seems like he is interested in me. He is maybe actually interested in doing a scientific catalog of where ghosts exist because he views them as quite likely a real phenomenon and something that can be scientifically documented. And he is being, you know, somewhat skeptical in his methodology here. He's like, well, we only have the negative evidence here, so we can't fully say that this is a rule. But here's somebody saying you don't get ghosts in Lombok, you do get them over here.

48:29Speaker 1:Yeah, this is a great point, because I think definitely at this point in his life, he was at the very least quite open to the idea that ghosts were real, that there was some sort of spiritual essence out there. Yeah.

48:42Speaker 2:And the really interesting aspect of that belief, at least to me, being the assumption that you could study this phenomenon in a scientific way. I mean, I think a lot of times you would have people who might be scientists or naturalists or natural philosophers in this era who have supernatural beliefs, but they don't approach the supernatural beliefs as open to investigation the same way their beliefs about the, you know, the forces governing the natural world are. And Wallace seems to be saying like, no, yeah, we could just we could study this.

49:17Speaker 1:Yeah. And I think we definitely have to look. at it within the context of the time to a time during which there are so many advancements are taking place. And Wallace, along with Darwin and others, are like right there on the front lines pushing this this theory of what is going to become known as as the theory of evolution, the theory of natural selection. And and therefore, like there's probably this this spirit of we can figure it all out. And we see this elsewhere as well, where people like, yes, we can we can actually measure these things. We can look and try and figure out what happens to consciousness when life ends. And in Wallace's case in particular, we we know that he comes to see some sort of continuation of the soul here. as being some special vibe, some sort of higher intelligence as being key to how evolution is working. And therefore, you know, he just sees it as part of the works. And therefore, it's something that you surely can prove out because we're proving out the other aspects of how the natural world is working. And if ghosts are part of it, if the spirit is part of it, then he should be

50:25Speaker 1:able to prove that as well. Yeah.

50:27Speaker 2:I mean, in a way, you could look at an interest in spiritualism as As a way of, you know, I think that none of the underlying phenomena were actually real, but as an attempt to empirically interact with the spirit world.

50:43Speaker 1:Yeah.

50:44Speaker 2:As opposed to just like having beliefs about it, but those beliefs being something that, you know, you don't interface with or interact with.

50:52Speaker 1:Right, right. Now, at the same time, of course, obviously, like entering in any kind of scientific enterprise with these concepts in mind, you can end up putting blinders up for yourself. And you can end up maybe engaging in some of these questions without complete neutrality. Right.

51:09Speaker 2:And I mean, of course, I think that is what we actually see in a lot of attempts to get really into the subject. But I would say that in principle, if there were spirits that made contact with the living on a regular basis, that's something that you could study. You know, it might be difficult to study because might be more like the study of psychology or something than like the study of uh of biology or nature yeah but uh but it could be something you could you could look into in a systematic.

51:36Speaker 1:Way right right and even the division of ghosts as well i mean especially in a place like indonesia you know it it ultimately speaks to other questions about the flow of ideas and the flow of religious faiths uh you know in a widespread and again as we've stressed very large spread out country that has various cultures wound up in it, various religious faiths. So that ultimately becomes the more interesting question, I think, outside of Wallace's viewpoint is, well, why would there be a tradition of ghosts here and not here? What does that say about the people?

52:08Speaker 2:Well, right, exactly. I mean, I think that's a fully legitimate and fascinating question to look into, not the question of are there literally ghosts here and not ghosts here, but like, why do you get these different beliefs and traditions in different cultures? You know, how does history feed into the developments One thing I would note is that Wallace says that, so he recounts this conversation where this guy who comes from Borneo says, hey, yeah, we've got ghosts back home. They don't have ghosts here. Wallace does note that the people of Lombok did describe a belief to him that some men had the power to transform into crocodiles in order to eat their enemies. So that's pretty cool. Seems different than a ghost, though.

52:49Speaker 1:Yeah, and I'm not sure how crocodile transformation would like how that ends up being interpreted by like European spiritualism of the time. But that's still fascinating.

52:59Speaker 2:Oh, I can just imagine the kind of distinction made like, oh, you know, our spirits are very real and legitimate. Nobody actually transforms into crocodiles. That's ridiculous.

53:10Speaker 1:All right. Well, we're going to go ahead and close out this episode of Stuff to Blow Your Mind right here, but we'll be back for a part two on the Wallace line. We'll discuss the concept in more detail and probably get into some specific examples too. Right.

53:23Speaker 2:In the next episode, we'll go into more detail about why it exists to the extent that it does, as well as sort of updates to the concept, like the idea of Wallacea.

53:33Speaker 1:Yeah. In the meantime, certainly write in and tell us all about your adventures in this part of the world, other parts of the world, and of course, your fieldwork. Researchers, write in about your fieldwork. We would love to hear from you, as well as recommendations for Future episodes of Stuff to Blow Your Mind, we always have an ear open for good ideas.

53:55Speaker 2:That's right. What is your equivalent of Wallace's dissecting room with every surface covered in ants? The box full of bird skins and so forth. Emitting odors.

54:07Speaker 1:Yeah, maybe it's not your work life either. Maybe it's your personal life.

54:10Speaker 2:Yeah, write in.

54:10Speaker 1:We'd love to hear from you. And just a reminder, Stuff to Blow Your Mind is primarily a science and culture podcast with core episodes on Tuesdays and Thursdays. But on Fridays, we set aside most serious concerns to just talk about a weird film on Weird House Cinema.

54:22Speaker 2:Huge thanks, as always, to our excellent audio producer, J.J. Posway. If you would like to get in touch with us with feedback on this episode or any other, to suggest a topic for the future, or just to say hello, you can email us at contact at stufftoblowyourmind.com. Stuff to Blow Your Mind is a production of iHeartRadio. For more podcasts from iHeartRadio, visit the iHeartRadio app. Apple Podcasts are wherever you listen to your favorite shows.