Science Friday - Squirrel Monkeys, Salmon Migration, The Realness. Oct 12, 2018, Part 2

Episode Date: October 12, 2018

Squirrel monkeys have big brains for their size, they’re chatterboxes, and they’ve even been to space. There may even be parallels between squirrel monkey communication and the evolution of human language, says primatologist Anita Stone. She joins Ira to translate the culture of our primate cousins, and talks about what they can teach us about ourselves. To be a salmon is to live an adventurous life: They hatch in freshwater streams, travel miles downstream to the ocean, and live years dodging predators in the open sea. But in order to reproduce, they must return back to that mountain stream, however far away. Research in 2014 confirmed that Pacific salmon can sense and respond to the Earth’s magnetic field—and that’s at least one component of how they find their home river. Now, a group of Atlantic salmon, descended from a group that’s spent 60 years in a landlocked lake, has also demonstrated this ability. Lead author Michelle Scanlon, a faculty research assistant in the Department of Fisheries and Wildlife at Oregon State University, explains the implications of this behavior for both wild Atlantic salmon and in populations kept, as many are, in fish farms nationwide. Plus: anthropologist Heather McKillop uncovered clues of a vast Mayan salt production system off the coast of Belize that may have been used to preserve fish and a place for trade. McKillop tells us how the Maya may have produced salt, and what this reveals about the economy of the civilization. And “The Realness,” a new podcast from WNYC Studios, tells the story of America’s relationship to sickle cell through Prodigy’s life, and death, from the disease.   Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

This is Science Friday. I'm Ira Flato. Broadcasting today from the studios of KCLU on the campus of California, Lutheran University, and Thousand Oaks, California. Later in the hour, a primatologist takes us into the world of South America's squirrel monkeys and what they teach us about our own evolution. But first, the Maya invented a sophisticated mathematics system that included the number zero. Yeah, zero. How to do that? to be invented. They used this in their calendars and astronomical studies. They also had farming systems and a complex political structure to govern the sprawling city networks. It was a complicated place. And the full story is getting even more complex. Last month, scientists surveyed a Mayan megacity in Guatemala that had over 60,000 structures. And this week, researchers say that the Maya may have also had a salt industry on the coast of present-day Belize. These results were published in the proceedings of the National Academies of Science. Here to tell us about the Mayan Salt Economy is Heather McKillop.

She's an author on that study and Professor of Anthropology at Louisiana State University in Baton Rouge. Welcome to Science Friday. Thank you. It's a great pleasure to be here. It's our great pleasure to have you. Thank you. You can make salt in a variety of ways. So what technique do the Mayans?

What were they using to make salt? Well, like people around the world, of course, everybody needs dietary salt in ancient civilizations and other farming cultures as well. But the Maya collected salt from salt flats off the north coast of the Yucatan, but in other areas like the coast of Belize where it rains a lot and they don't have the solar evaporation possibilities. they were boiling brine in pots over fires. And we found in southern Belize, below the seafloor, we found wooden buildings, which indicate they were doing this salt production indoors on a massive scale. Was this surprising and unexpected?

Yes, it was. I was really doing a regional survey looking for sites after having worked elsewhere on the coast. And I was looking in shallow areas in the water because I knew we'd identified sea level rise, and we found sites that were about a meter below the sea floor. And we excavated them, and they had pottery that I identified as salt-making pottery. They haven't published a book on the fine, salt, white gold of the ancient Maya. But in 2004, we made a major discovery, and that was that below the seafloor, it's made. Angrove Peat, and the peat, which is resulting from seal-level rise,

preserved wooden posts. And now we've mapped over 4,000. We've actually mapped 4,042 wooden posts and other architectural elements at 110 sites where there are wooden buildings that are associated with this salt-making material. And the significance, I guess, is that wood normally decays in the tropical landscape of Central America. And I'd already written a lot, done a lot of research about these salt making sites, and we

actually didn't see the wood at all until 2004. So how would the wood have been used in the salt production? Well, instead of being an activity that might have taken place outdoors, boiling some salt, this was

the wood was in formed rectangular outlines of buildings, and so these buildings I identify as salt kitchens by comparison with modern and historic salt making in the Maya area today and elsewhere around the world. So this was an infrastructure where they would get maybe a couple of dozen bowls over a fire at once and continuously work on evaporating the brine by fire. They would store their firewood. They would store their salt cakes. They would store wet salt and brine and really dedicate.

the space inside buildings to salt making. So you found a whole salt production technique, a whole salt production line, and they were very serious about this. They were really serious about it, because all those big Maya sites that you talked about and then the new discoveries from the LIDAR, people still need dietary salt. Biologically, they need it, and they didn't have it. They didn't have it. And you also discovered that they were using salt to preserve their fish, which...

Yes. We've heard about, you know, in Western cultures. Exactly. And so the peat, mangro peat below the seafloor, perfectly preserved wood, but it did not preserve bone. And because of all the posts that we found in these wooden buildings, I figured that the stone tools, the church stone tools, were used for chopping down trees and sharpening the posts and other woodworking things that they were making like paddles and canoes. So when I contacted my colleague, Kizua Ayoama, who is an expert on studying the microscopic damage to the edges of stone tools and asked him if he would collaborate on this project, he did. And he found that a minority of the stone tools were actually used for woodworking, and most were used for cutting fish or meat or for scraping hides or, you know, scaling fish. And that was, so that really changed things for us.

So you found that they were using salt for a lot more things than had been suspected before. Yeah, I thought, so previously I had built up a story based on, I think, some good solid evidence that they were producing a tremendous amount of salt. And they were probably trading it, storing it and trading it in the form of salt cakes in standardized units based on the standardized dimensions of the pottery vessels. and they were taking salt as a commodity to markets up rivers to inland cities to trade at marketplaces. And so the discovery of the fish adds to the story by saying, well, yes, I think they were also taking salted fish. And both of these are storable commodities that really are good risk management strategy for a household economy and also for whoever buys the things at the inland market. If you don't have to use it right away, you can hold on to it for a while.

That's amazing. I mentioned that the LIDAR survey had found 60,000 structures in Guatemala. What is this revealing about the complexity of this civilization? Well, like you said, the Maya had the concept of zero. They probably used that, did complex calculations in their marketplace. as well as the calendar, and they had a very dense and large population of cities, towns, and villages.

Where we are on the southern coast of Belize, everything has been submerged by feelable rise and covered in mangrove. But in the interior and the rainforest, there's a surprising number of sites. I think the lighter has really transformed our ability to look at sites in a whole, different way. First of all, see them before you start excavating and make a plan, but the density of

population is really impressive. Yeah, is there enough, you know, resources, people power, anything, equipment that you can, enough to go in and see these 60,000 different structures and the vast expanse of the civilization? I mean, are you able to do that? Well, I think that fortunately, for my sites, they're all underwater and you can't see them, and they're below the seafloor, and it's really hard to see anything at all. You really have to know what you're looking for, and I know where they are. We also have GPS to help us find them. And in the rainforest, these sites are still protected in the rainforest.

So even though they're visible on LIDAR, unless you have access to the LIDAR data, you can't really. see these sites, and it's still very difficult to get them, get to them. But I think in terms of the archaeological projects that work in the interior of Guatemala now, they'll be able to plan their research because they'll be able to see these things on LIDAR and make plans before they go in the field, which is, you know, like working in the desert. Yeah, yeah, I know it's interesting. What is, I have a couple of questions for you. One is the discovery of this, all the salt, making, does it change your ideas about the economy of the Maya? I mean, we're using this as money, using it for trade, all the salt that they were mass producing? Yes, I think what it really does

is underscore the fact that the classic Maya had a marketplace economy, and it was largely a lot of trade in a regional economy. So they had various different kinds of exchange and acquired things from short distance and long distance. But I think it was based on the household economy, sort of a family business, in this case, making salt and making them in standardized shapes and sizes. So, for example, I looked at the three different sites of our Canes Creek saltworks, three different areas, and they were making their pots were different in their dimension. slightly different, and these were statistically significant differences

suggesting to me that they made their own pots, and they made the salt, and they were doing it as part of a household economy, and then now we know that they were taking the salt cakes, standardized units of exchange and storage, and also the salted fish, taking them to inland sites, and they were trading them. The Maya, of course, didn't have a currency per se, but they did have currency equivalencies, and I think salt cakes can be discussed as a currency equivalency.

How much of this can be actually reconstructed? You say a lot of it was underwater, you know, sea level rise. I understand you found a canoe paddle, a wooden canoe paddle? Yes, in 2004 we found at Site 15, we found the first wooden post, and then we started finding posts everywhere, and we went back to some. site 14 and found a full-size wooden canoe paddle, 4 foot 7 inches long, which we've now done a 3D image of, and it's reconstructed, and we've printed a full-size replica of it. We found a canoe as well, and so that's sort of the infrastructure of distribution.

Well, I want to thank you very much, Dr. McKillow, for taking time to be with us today. Well, come down and swim with us sometime and see for yourself. Thank you very much. Putting it on my list. Heather McKillop, author of a study that was published in the proceedings of the National Academies, Professor of Anthropology at Louisiana State University in Baton Rouge. We're going to take a break and come back and talk about the secret lives of squirrel monkeys. Didn't know they had a secret life.

We're uncovering it here. You want to know the details? Stay with us. We'll be right back after this break. This is Science Friday. I'm Ira Flato. In May of 1959, a small squirrel monkey from the jungles of Peru sat atop an American Jupiter rocket awaiting her blast off into space. Miss Baker was her name, and after nine minutes of weightlessness, she fell back to Earth where she became an instant celebrity inundated with letters, letters from school children, and even mobbed at press conferences. One of the first two American animals successfully launched into and returned from space. Ms. Baker's flight was a study in how we humans might fare in orbit in space.

But there's a lot to learn by studying these small cousins of ours right here on Earth, analyzing their communications, the structures of their societies, and the brainy waves that they navigate their world, as my next guest does. Anita Stone, Assistant Professor of Biology at California Lutheran, University here in Thousand Oaks. Welcome to Science Friday. Thank you. It's great to be here. You know, I remember squirrel monkey, that squirrel monkey for my childhood as one of the first animals that went into space. Wow. Well, what got you fascinated with studying? So I'm from Brazil, and I went to grad school here in the States, and I knew that I wanted to work in the Brazilian Amazon for my

research, and I started reading about squirrel monkeys and became fascinated with them, and then I saw them in the wild and it was just a perfect combination to look at the questions that I was interested in. So off I went to Amazon and Brazil for 12 months and I thought it would just be one, you know, one project, one season. But the more time I spent there, the more I became fascinated with all kinds of questions about them. And I couldn't find a lot of answers in the literature because there really aren't that many people studying them in the wild. I kind of know why now, after so many years, they're a little bit of a pain to study. They're very challenging.

But, yeah, that's how it all started. Wow. So how many do you study? How many, is there a group number of you study? Yeah, so the groups are very large. My groups have 30 to 50 animals. So I monitor three groups regularly. Do they each have each personalities of the row, and you give them names?

They keep track of them? Some. So one of the challenges of working with squirrel monkeys is that because they're so small, and by small, I mean, we're talking a kilogram max, so that's about two pounds. There's 50 of them, and they move quite fast. They're pretty active. So it's not that easy to individually identify them. particularly the juveniles because they kind of look very similar.

But there are some adults that stand out. You know, if they have a certain more dominant or forceful personality, yeah, they do stand out. Okay. Give me a typical day in the life of a squirrel monkey. Okay. So squirrel monkeys wake up really early. Usually by 5 a.m., they're already moving out of their sleeping tree. and they spend a lot of time active all day.

They're nonstop. They eat fruit, and they eat mostly insects. And so they spend a lot of time foraging in the morning for insects. But really, that goes on all day. When it gets a little hotter in the day, they tend to rest, but rest for a group of squirrel monkeys is about 10 minutes. And then they keep on foraging, and they don't go to, sleep, we follow them pretty consistently, and they don't usually go to their sleeping tree until

about seven. So they're pretty active all the day, 12 hours. I hear that they have a strange way of eating grasshoppers. Yes. So grasshoppers are one of their favorite items, so to speak, and they catch these pretty large grasshoppers sometimes. And the way they do it, the way they handle it once they grab it is they hold it by the bottom and with head up and then they bite off the head, kind of like an ice cream cone, and then

they slurp the insides, and then finally they'll eat the legs and the wings sometimes. And they seem very happy while they're doing it. Wow. And I understand they're not afraid to attack a wasp nest. Right. Wow. How do they do that? Yeah.

So I've only seen adults do it, but I've actually seen. it quite a bit. So what they do is they will approach a wasps nest, a particular species, and they will knock it down very quickly to the ground. So these are nests that hang pretty low. And once the adult wasps desert the nest, the adult squirrel monkey will basically move in and eat all the larvae that's left abandoned in the nest. Wow. So they're pretty brave. They're pretty bad.

And patient. And patient, yes. Those wasps are not leaving so fast. Right. Yeah. I've done this myself. We have a clip I'd like to play, and then maybe you can translate for us what's going on here. Let's, of the spider monkeys.

Let's hear that clip. Scarl monkeys. I said spider monkeys. Everybody does that. Everybody does that right? Yeah. Okay. Tell us what we're listening to.

Okay. Okay, so this was recorded in captivity, and what it sounds like to me is that these are contact calls, but these are made by animals that are not very close by. These are longer contact calls. So they're basically talking to each other from, you know, not a very close spatial proximity. Can you actually tell the individual monkeys in there? Can you recognize their own? I can recognize, yes, the sender and the receiver. But when there's, you know, 10 of them in a tree, it's kind of hard to figure out exactly, you know, who's making the vocalization.

We have another clip that sounds a little bit more, how shall I put it, contentious. Okay, so that's definitely a little squabble. It doesn't sound like a serious fight to me, like something we'd hear in the wild. My guess is that there's an adult male at least in there, making one of the noises. And my guess is that it's a quick fight over some food item. You know, it's interesting as I was listening to that. It just struck me that when we see movies of jungles or, you know, that's the sound that we hear. Is that right?

It's usually this, is those squirrel monkeys that we're listening to? It might be birds, actually, because squirrel monkeys sound a lot like birds. when you're in the forest. That's what my students usually notice, is that isn't that a bird? And you have to listen really closely to be able to identify that it's a group of squirrel monkeys instead of birds. How hard was it? How much time has it taken you to know the difference and to study the sounds that they make? So it's not something that I personally study, but just from studying there for 18 years, from being with the monkeys, you just get used to it.

It probably took me the whole 12 months to figure out what the different vocalizations were. But my field assistant, who's a local field assistant, he's the monkey whisperer, and he knows everything about score monkeys. And so he can tell right away if it's a bird or a troop of monkeys. How long has he been doing that for? A little longer? He started with a couple years before I got there. So he's been doing it for about 20 years.

The monkey whisper. Yeah. Do you call him that? Yes, sometimes. Does he like it? He loves it. Is there anything that we can learn about the human language or evolution of our language from studying the squirrel monkeys? Yeah, so it's interesting that you bring that up because, so there's a hypothesis that was proposed about 20 years ago called the vocal grooming hypothesis.

and the idea here is that you can try to understand the evolution of human language. So the idea is that humans started living in social groups that were increasingly large. And so manual grooming, sort of the kind we've seen baboons and macaques, became less feasible, really. And so the idea is that humans would have invented an alternative form of grooming, vocal grooming. So it would be a way to maintain contact and social bonds with their friends, and that would leave the hands also free for other tasks. And the idea is that that eventually would have evolved into human language. Now, squirrel monkeys for living in groups so large, they're actually pretty asocial. They don't groom.

We expect primates all to do that, but they don't actually groom each other. they too live in social groups that are large. They don't groom, and they talk all the time. They're constantly chattering. It's nonstop sound when they're foraging, when they're traveling, when they're just resting. And so I wouldn't be surprised if one of the ways that they maintain their social connections is actually through vocalizations. In some ways, you could say that it's not that different from keeping in touch with your friends

by texting when we're far away from our friends. That's what we do all the time is talk, right? So instead of the grooming, they're bonding or talking by actually talking. They're communicating by talking instead of bonding that way. That is my guess. And we might have done that ourselves. Correct. Evolutionarily.

Yeah. It hasn't been studied in squirrel monkeys, but I think that's a pretty good guess. Oh, there's something for you to do next. Yeah, really. Study that in squirrel monkeys. Are they sort of the pacifists compared to some of the more litigious primates like chimps who are actually out there being aggressive all the time? They're definitely not like chimps. They're like chimps only in the sense that they have really large brains.

But in terms of aggression, they don't defend territories. So the groups are large. They don't defend territories. So they can be overlap in areas, home ranges, for two or three. three groups, they don't like to meet very much, but when they meet, they pretty much just go their separate ways. There's not a ton of aggression in the group, except during the mating season, between adult males.

Then things can get pretty ugly. Well, speaking of that, you bring up a good point because squirrel monkeys, there's society is female-dominated. Correct. For this species, yes. The species. Yeah. Does that have anything to do with the fact that they are not that aggressive?

Possibly. So for female-dominated species, we mostly see that in lemurs, really, but for anthropoid primates, that's pretty rare, really. One thing about squirrel monkeys is that they have very interspecific differences between in their life histories, and all species have a very high degree of maternal investment. But it's interesting to me that the two species where we see female dominance, the females nurse the infants for a very long time. So possibly they getting priority of access to resources. That might be something that's going on. So with the domination of females in these species, the men are the men pulled back? That they know their place a little bit more? That's exactly how I would describe it.

There's not that much aggression from females to men. males, but the males kind of know their place. The center of the groups is formed by adult females and their juveniles. And the males, except for the mating season, they pretty much stay on the periphery of the group, minding their own business. And if they try to get too close to the infants and juveniles, the females are not happy. I'm Ira Flater. This is Science Friday from WNYC Studios. Talking with Anita Stone about these squirrel monkeys. So any idea

why society would evolve one way or the other to have one gender dominate versus the other? Well, we know that for most species, females invest a lot more in reproduction than males

do. In primates, you have gestation, lactation, you have the difference between sperm and eggs. So from studying primates where there is female dominance, we know that sometimes they live in very harsh environments. And so females having that, this is true in lemurs, where females have priority of access to resource may have something to do about where they live and how the resources are distributed.

And squirrel monkeys were not exactly sure, but of the seven species, there's only two that we know of that are female dominant. Yeah, let me ask you about something I learned in, is that the squirrel monkeys have something called that we might consider it a strange behavior, but for them it's called urine washing? Yes. So this kind of became a side project in my research group because a couple students got really interested in it.

So there's this odd behavior that's done. It's not just squirrel monkeys, but capuchins do it too, where an individual will urinate a few drops onto the palms of their hands and rub it on the sole of the foot. and sometimes repeat it on the other side. It doesn't take very long. It's pretty quick. And we don't really have a good idea about why this happens. If you look at the literature, most studies were done with Capuchins in captivity.

And different studies point, it's points in all different directions. Some things that have been proposed are that it could be a form of sexual communication between adult males and females, even thermoregulation. as a way to cool down because squirrel monkeys don't sweat. But what we found in our population is that juveniles do it much more than adults. And it also seems to be, so that really almost rules out the sexual communication idea, because juveniles are doing it more. But it also seems to be linked to stressful situations. So, you know, fights in the group or some sort of turmoil.

And so one thing that had been suggested, which I think our data support, is that it's some form of anxiety displacement, sort of like a stress reliever, much like, you know, wringing your hands when you're nervous or something like that. But we definitely need to dig deeper into that. So it's not like a territory marking thing that to see other animals do, right? Right. So that actually has been looked at a long time ago in a semi-captive population that it's not territory marking. It's not a way for one individual to know where they're supposed to go to follow the group. That doesn't seem to be the function of it. But it could be that it has multiple functions. It could mean something for adults and something else for juveniles. You know, we've seen issues where animal cultures we're learning more are passing. their culture down from one to another? Do you see that in the squirrel monkeys at all?

So I've never actually seen a squirrel monkey use, do what we would consider tool use in the wild. I did hear about something that sounded kind of like it in captivity. So in terms of passing things down, I would think more that the constant proximity of the females with the juveniles and their constant communication. I don't know what they're talking about, but the wasps nest foraging could very well be something that's, you know, the juveniles learned by observing the adults. That's terrific. I want to thank you both for taking time.

Thank you for taking down to be with us to Anita Stone, Assistant Professor of Biology, California Lutheran University here in Thousand Oaks. Fascinating stuff. I hope you get back in the jungle soon. Thank you. It's great to be here. We're going to take a break. When we come back, we're going to talk about salmon, swimming hundreds of miles to spawn and the magnetic sense of direction they have.

Stay with us. We'll be right back after this break. This is Science Friday. I'm Ira Flato. You know, every year, salmon go on the most important journey of their lives. After living years in the wild oceans, they must swim back to the coast to one very particular river mouth and then, retrace miles of tributaries, branches upstream, until they finally arrive in the Little Freshwater Spring where they were born. How do they do this? Well, like any good trip,

you need a map, and not just a compass. That's just telling you where north is. You also need to know the location of the place you're going to get to. Is it straight north? Is it more northeast? East and south? Well, you know, a few years ago, research has concluded that, what they had long suspected, that Pacific salmon can detect the magnetic field lines of the Earth. Their map is their magnetic. And what about their Atlantic dwelling cousins? And when you let fish live in quiet, landlocked lives, you know, they live their whole lives with dozens of generations, landlocked. What happens to that map?

Here to explain more is Michelle Scanlan, a faculty research assistant at Oregon State University in Corvallis. Welcome to Science Friday. Thank you for having me. You know, I just said it, but Salmon live impressive lives, right? They travel all that way. How many miles do their journeys take? It is pretty impressive, and their journeys can be hundreds or even thousands of miles to their oceanic foraging grounds. And they usually hatching these tiny streams, miles inland, and they have to go back there.

That's correct. And they don't just have to navigate. upstream, they have to find the right stream to go. How do they do this? They don't have a, well, maybe they do have a GPS of some sort in there. Yeah, this salmon have a diverse array of tools that they use in order to navigate. And so when they reach streams, they generally would use their sense of smell. But in terms of, say, oceanic journeys and voyages, they use something more broad scale.

And in this term, we think they're using magnetic maps and magnetic maps. information. Now, I know that your research is looking at a different group of salmon, the Atlantic salmon. What makes them so interesting to you? This is rather interesting opportunity because the Atlantic salmon that we used for this study are actually descendants of individuals that were transferred from a landlocked lake in Maine to a landlocked lake in Oregon over 60 years ago for recreational fishery. So these fish have never had access to the Pacific Ocean. and have never set thin outside of a lake or in the instance of our fish outside of a hatchery. And yet you found that they still have these geomagnetic maps in them that they would have needed had they not been landlocked?

That's correct. And how are they able to retain these and why? That's an interesting question. So salmon, when they use magnetic information, they can use different. aspects of the magnetic field, especially for maps. And so the Earth's magnetic field has a couple of different components. One is the strength of a magnetic field, or also known as magnetic field intensity. And so those intensities are stronger at the poles and weaker at the equator.

Another aspect of the field that they can use is called inclination angle, and that's the angle at which magnetic field lines intersect the surface of the Earth. And so they are steeper toward the poles and shallower at the equator. And both of these components predict are predictably variable across the surface of the globe. So it's super convenient because these gradients of intensity and inclination angles aren't parallel. So they form a type of bi-coordinate grid over much of the earth. And so animals can actually derive both latitudinal and longitudinal information from the magnetic field. Do they have little magnets in their bodies that can do that?

So the mechanisms behind magneto reception are still unclear, but one of the leading hypotheses is that salmon and other species have tiny chains of magnetite, and that is an iron oxide mineral that has magnetic properties. And so these chains of magnetite are associated with nerve cells, and the thawks. and the thought is that these chains can be pulled by the earth strength magnetic fields. And so changes in both the field strength and or the inclination angle can result in action potentials. So these magnetic structures are thought to be found in the nose and also the lateral line, so along the sides of the body of a fish.

But the magnetoreceptor itself is still elusive. Now why is it important to you? Why does it matter that they can still detect these fields? Well, it's a rather interesting question. So we wanted to know whether landlocked members of species that could go to the ocean retain a map sense, just a point of curiosity. And we also wanted to know if Atlantic salmon also possess its ability. It's another group of individuals that possess magnetic maps.

out of diverse amounts of species. But we also wanted to know what happens when you test animals in novel sort of magnetic environments. One, can they even detect a magnetic field? But two, can they actually differentiate between those fields? And three, how do they actually respond? And so how did you go about testing these fish? So the eggs from the individuals at the Lake and Oregon were transported to the Oregon Hattray Research Center, where they were reared and subsequently tested.

And so we tested these individuals using a series of magnetic coils. And essentially, it's a series of wooden frames that are wrapped in copper wire. And when you attach copper wires to an electrical power supply and crank electric currents through the magnetic coil, A byproduct of that electricity is a magnetic field. And the really cool part about our coils is that allows us to alter the direction and also the amperage of current in order to allow us to simulate magnetic fields from almost anywhere on Earth. So what you're doing, I know from my basic physics, you know, in great schools, if I take a magnetized object and put it next to some metal, it will magnetize the metal in a certain. direction. So that sounds to me basically what you're doing to the fish. You're magnetize them setting their magnetic structures up to know where they are in a certain direction.

Yes, so we're presenting them with magnetic fields, essentially, that hopefully interact with what we think are these tiny chains of magnetite, right, that somehow connect with the nerve cells. Right. And so how did the fish respond to this? So we evaluate the movement, fish movement, by centering the fish in the coil. So there's a platform with a bunch of testing arenas. We have one fish per arena. And then we have cameras that are mounted above those testing arenas to give us a bird's eye view of the test subjects during the trials. So what this means is that we are generating thousands of photos of our fish.

And so we take photos and we assess the position of the fish's head relative. to magnetic north. Wow. That's terrific. And, you know, do you know how good the resolution they have is? I mean, just how accurate they can be to these magnetic fields? That is a question for future research, so we don't know how fine or core scale the magnetic resolution of those maps is, yeah.

So speaking of looking forward, what would you like to do? of other experiments or equipment would you like to have to test these fish again? So we have a whole number of experiments that we have talked about over the years, but one of the experiments would be to actually look at magnetic resolution of those maps. So having a series of points, moving them closer and closer together, and to see how fine or coarse scale their responses actually are. So could you save endangered salmon then? by knowing some more about them.

I mean, it always helps to know more information about a species that you're trying to conserve. Knowing how they're making movement decisions would certainly be helpful and probably a tool in salmon conservation, but certainly not the only thing that we can use to try to preserve them. Well, good luck to you in your future experiments. All right. Thank you very much. Michelle Scanlan is a faculty research assistant, Department of Fish. and Wildlife at Oregon State University in Corvallis. And she was the lead researcher in an article appearing in the proceedings of the National Academy of Sciences.

In the late 2000, a rapper known as prodigy released a song called You Can Never Feel My Pain. You Can You See, Pay attention to the words because the story is deep. And then out of crisis since before I can walk. It gave me strength, though. Nowadays I hardly told. And for many cold-hearted anti. I won't play sports. I rarely joke or play games. Take it how you want.

My handicapped took his toll on my sanity. My mom got me at the shrink it like 13. And for many of his fans, it was just another track off the rapper's first solo album. But to people who knew Prodigy well, the song contained a secret message. The pain referenced in this song was from sickle cell anemia, a rare genetic blood disorder, that disproportionately affects African Americans. And in the U.S., today, 100,000 people have sickle cell disease. Two million people carry the trait for it.

A podcast called The Realness tells the story of America's relationship to sickle cell through the lens of prodigies' life and death from the disease. Christopher Johnson is co-host of The Realness, a podcast from WNYC Studios. Christopher, welcome to Science Friday. Ira, hello. Nice to talk to you. Likewise. How did you come across Prodigy's song and his story of sickle cell anemia?

So we at the health unit, my co-host, Mary Harris and I here at WNYC, we went looking, trawling for some new stories to tell. And we wanted to move away from just looking at one-off stories that just lasted for a few minutes. We actually kind of wanted to do these deep dives and tell deep health stories through the lives of real people. And so Mary found this story about sickle cell anemia and how it kind of represents a lot of the health disparities in this country and felt like it could be a good springboard. And one of the doctors that she spoke to asked her about Prodigy who had recently died. He had sickle cell. And she knew about the sickle cell piece of it. I knew Prodigy's music from being a hip-hop fan from when his group Mob Deep was getting big in the mid-90s.

And we kind of took it took it from there. I'm Ira Flater. This is Science Friday from WNIC Studios. Now, the lyrics were pretty stark. My handicap took a toll on my sanity. Pretty strong words. Yeah, yeah. I mean, it is, as far as I know, the one song that he wrote explicitly about his life with sickle cell anemia. Even though he was born with it, of course, and it was something that really, really shaped his life. It can be an excruciating disease. It's extremely painful, especially for him. And he grew up having these crises from the time that he was a baby.

And it shaped his music a lot, but a lot of people didn't necessarily know that he had sickle cell until he passed away. They didn't know that, even from his music. No one was questioning why did you use those lyrics? Yeah, yeah. I mean, he people, well, people knew and they didn't know. He didn't talk a whole lot about it. If you look at the full sort of canon of his music, both as half of the hip-hop group Bob Deep and also as a solo rapper, he just didn't talk about it a lot. As an African-American, did this story hit home for you and serve as a catalyst for the realness?

It absolutely did. I mean, for me, it's both about sickle cell specifically, and it's also about the reality of health care disparities in this country. And even for someone like Prodigy, who as a celebrity, as this superstar, as someone, especially in the mid-90s, was successful and had access to the best treatment. Even as a child, he had one of the best doctors working in sickle cell. He still went through what he went through. Were you a little surprised when you knew that he had sickle cell that he did not talk about it in his music as something I'm using my music as a way to inform more people about? it. I mean, I wasn't really surprised. I mean, knowing music from that era and looking at the image of a group like Mob Deep, I didn't have a chance to ask Prodigy this, but I would guess

that along with that music comes an image of toughness and sort of impenetrability. And certainly sickle cell and this idea that he was constantly racked with pain was probably not something that he wanted to put out there. In fact, Tupac in one of his songs that was basically a track aimed at all these other rappers included Mob Deep. And in that song, Tupac used, he sort of weaponized Sickle Cell and used it as kind of a part of his disc at Mob Deep. So Prodigy probably was not interested in putting out there that he had this disease that made him, that may have made him appear weak.

I imagine in preparation for your story in the realness, you must have had to learn a lot about sickle cell. Absolutely. A lot of Linus Pauling tape. And you learned why this disease is so painful what it does to the body. Yeah, absolutely. So very, very basically, the way that it works is that normally our red blood cells are sort of shaped like lifesavers, and they're smooth, and they move through our body fairly smoothly. What sickle cell does, what Linus Pauling found was that it causes this glitch in the hemoglobin, which is part of our red blood cells.

It's what carries the oxygen through the blood. It causes the cells to kind of take on a half moon or like a fingernail clipping shape, is how I looked at it. They sickle, and they get sticky and tacky, and they can clog up the veins. And when you exert yourself, exercise, walking upstairs, even, it can cause pain all over the body. And that was probably... And a lot of people can be carriers of it and not know that they have it. Exactly. You can have the trait and not have full-blown sickle cell.

And you can also have full-blown sickle cell and not experience. it to the extent that Prodigy experienced it. Yeah, and I want to thank you very much for taking time to be with this today, Christopher. Hey, thanks for having me on it. It's a great series. Christopher Johnson, co-host of the Realness from WNYC Studios, and

this was a great story. Thanks again. Thank you. And you can check out The Realness podcast by going to Science Friday.com slash the realness. And we're going to thank all of folks who helped us today. Want to thank BJ Leideman who composed our theme music,

and also thanks to Dr. Michelle Mulholland who provided us with those squirrel monkey calls. And a very special thanks to all the great folks here at KCLU who made us feel so welcome in our studios in Thousand Oaks. And if you missed any part of our program, like to hear it again, we're always there. Every day, every day now is Science Friday. You can hear us on all kinds of Facebook, Twitter, Instagram accounts,

and subscribe to our podcast. Have a great weekend. In Thousand Oaks, California. I'm Ira Flato. Thank you.