How Pigeons Navigate The Planet

Okay, so here’s a question. Can you guess what ancient humans used for communication even as far back as 1300 BC? I’m talking about before these things, obviously before smartphones. And well, based on the title of this video, you can probably guess what the homing pigeons, also known as messenger pigeons, animals on whom humans relied for thousands of years. As a matter of fact, these birds were even depicted in various types of ancient Egyptian art because even Egyptians used them for the same purpose. As a matter of fact, they saved a lot of human lives because of their unique ability to find their way home no matter what. Here’s actually a really cool picture of a Royal Air Force crewman who caring home pigeons as a type of an emergency communication in case of a crash or in case a radio stops working. And so for centuries, they’ve been used for anything from war reports, business deals, and even to send love letters from one location to another. Yet, despite this relatively long relationship we’ve had with these birds, we never actually knew exactly how they’re able to do this or how they’re able to use their internal compass to navigate to a very specific location. Although obviously for many years, biologists had a few assumptions. But we definitely know that whatever it is, it seems to work just like in so many other animals like for example whales and dolphins by using the earth’s magnetic field to navigate. But exactly how? That’s actually the question we’re going to be tackling in this video. And so how wonderful person, this is Anton, and today we’re going to be discussing this recent study you can find in the description where scientists potentially solve this mystery once and for all. Or to be more exact, they potentially found a specific sensor that seems to work in these birds and allows them to navigate using the magnetic field. And so here, this fascinating new study from the University of Bon and the Maxplank Institute of Animal Behavior might have finally found this quantum compass and it seems to be in a place nobody has ever expected. It seems to be inside the liver. But before we dive into this new discovery, let’s discuss some of the previous assumptions based on some of the previous studies. Mostly because back then it actually made quite a lot of sense. And generally there have been three main theories on how many different birds tend to sense the magnetic field. The first one is referred to as chemical magneto reception which in this case might use a very specific protein referred to as a cryptochrome. This is something that might be inside the eye. And here the idea was that the light generally triggers a reaction that then lets the birds see the magnetic field which they can then use to navigate and to create internal maps. In other words, here the assumption was that they’re able to perceive the magnetic lines and are thus able to navigate because their vision allows them to do so. But this didn’t really explain how birds can also navigate in complete darkness. And on top of this, this particular idea was extremely difficult to prove. In other words, there was not a lot of evidence, just a lot of assumptions. So far, none of the experiments showed anything. The second proposition or the second hypothesis involved iron particles and specifically particles inside the bird’s beak that would basically act like very tiny needles sort of resembling a compass needle signaling the brain the overall direction of the field through what’s known as trigeminal nerve. In other words, by having these very tiny needles inside the beak and by then flying through the magnetic field, they might be able to sense it and thus once again map it inside the brain. And lastly, the third and a more theoretical model suggested that the magnetic fields might directly affect ion channels inside the ear or the brain. In other words, the magnetic fields might directly affect certain cells and thus create certain effects that could then be perceived by birds without any additional mechanism. But all three of these propositions were mostly hypothetical and lacked any specific evidence or basically until now we did not really know what physical mechanism might allow them to sense the fields and of course how they’re able to then navigate. And this is essentially where this new research comes in. Here scientists found that pigeon livers and spleens have surprisingly strong magnetic properties compared to other body parts and compared to other animals. And so here by analyzing various body parts using electro microscopy they actually identified a specific type of a white blood cell called a macrofase that seems to play some kind of a role. Now if you’ve taken high school biology you probably remember that macrofasages are part of the immune system. Their main job is to actually eat various pathogens and all sorts of debris inside the body through a process referred to as fagocytosis. And when you get a lot of them eating something inside, they then eventually result in the production of pus. So basically pus is a collection of these macrofasages all together. Although technically it does contain some other stuff too. And while in pigeons these macrofasages are responsible for breaking down old red blood cells which are normally full of ironrich hemoglobin with this iron then stored inside the cells as a protein referred as feritin. A protein that resembles this. And here researchers discovered that these iron filled macrofasages seem to possess a property referred to as super paramagnetism. A fancy word for a property that happens when very tiny magnetic particles, usually nanoparticles, tend to produce a very specific magnetic flip depending on the temperature or essentially it’s a flip in the magnetic field direction when the temperature changes. And well in a large magnetic field these particles align and create a very strong magnetic response much stronger than regular magnetic materials. And while looks like in pigeons these nanomagnets are thought to then align with the earth’s magnetic field. In other words by having these cells filled with feritin they then start to act like very very tiny magnets constantly aligning with the magnetic field of planet earth. Basically becoming a kind of a supermagnetic cell. But the thing is in this case a sensor is still kind of useless if it cannot talk to the brain which is actually why this particular study is so exciting. Here researchers found that these magnetic macrofasages seem to be located within two micrometers of nerve fibers in the liver which basically suggests a kind of a direct connection from the liver to the pigeon’s brain through these nerve fibers in the liver. With the explanation and the main theory here now suggesting that as the magnetic field changes, these cells provide a signal perhaps through mechanical pressure or chemical release that these nerves then carry to the brain allowing the pigeons to imagine what all of this looks like. But this was not just a theoretical proposition because here researchers tested this and they did this with a very elegant experiment. They essentially took 34 pigeons and divided them into two groups. One group was given a drug referred to as cladronate whose main purpose is to basically wipe out macrofasages in the liver temporarily. In other words, they suddenly had almost nothing inside the liver including of course the cells filled with feritin. The other group was the control. Nothing was done to them. And well then these 34 pigeons got to fly around on a clear sunny day. In this case, both groups had no trouble finding home. And that’s because, as we know, pigeons very likely use their eyes during daytime and mostly use sun for navigation. But on the overcast day or at night, something inside of them switches and they actually start to rely on the magnetic field a lot more. And so when they tested them on a completely overcast day when the sun was invisible, the results were definitive. Normal pigeons were home in about 70 minutes. But the pigeons without their liver compasses were completely lost. As you see in this image, without these macrofasages in their liver and without these feritin nanop particles, all of them displayed what’s known as the random spatial orientation. In other words, they were flying in different directions in circles and failed to return until the clouds cleared the next day. here. This was a definitive proof that they do seem to use liver for navigation and specifically these macrofasages filled with iron while also confirming that normally they still prefer to navigate using the sun and the magnetic field seems to be secondary. But it seems to be absolutely necessary for navigation in overcast or night conditions without which they basically get lost. And honestly, this was a brilliant study and a brilliant experiment. Obviously, these birds returned back to normal once the medicine wore off and so no one here got hurt. But this is obviously also very important for biology because it fundamentally changes our understanding of how animals interact with the planet and how some of this potentially evolved millions and millions of years ago. Because here this suggests that it’s actually the immune cells which we actually thought only fight infections that seem to also function as sensory organs and specifically in magneto reception. And interestingly, not so long ago, there was actually another study on evolution of blood cells that even suggested that many different blood cells actually took approximately 700 million years to evolve and very likely came from the same ancestor which sort of resemble this macrofage that was described in this particular study. In other words, these individual macrofasages and individual blood cells seem to have a much more diverse role in our bodies and a much richer history involving functions we never imagined. But obviously in this case, the discovery also possibly goes beyond pigeons because we know that many animals navigate very long distances without maps and very often use magnetic fields as well. For example, sharks in the deep ocean, migratory bats, or even blind mole rats seem to also be able to navigate through the use of magnetic fields. And so, because of this, scientists now suspect that these other animals might also be using very similar quantum immune cells to find their way. And so when it comes to animal migration and animal navigation, that gut feeling we often talk about when it comes to going somewhere might actually be a physical magnetic signal coming from the liver. Although in this case the question is of course how much of this applies to humans too. Now there was a much older study we discussed a few years back where humans potentially also were able to navigate using something in complete darkness but surprisingly only when we’re very hungry. I think that video should be somewhere in the description. But still, in this case, it would be interesting to find out if this is something that humans also still possess and if we can also maybe walk around and map environments using these tiny magneto receptors inside our livers. And so here, this is a pretty good reminder that even things we thought we understood or took for granted and animals we’ve coexisted with for thousands of years still seem to hide these profound mysteries that are only now being discovered in regards to their biology. And so even now we’re still learning how life uses various types of machinery and various types of quantum and physical effects in order to achieve things like navigation that for many centuries basically seemed like magic. Anyway, on that note, at least for now, that’s all we have. Once there are some additional discoveries, we’ll come back and discuss this more in some of the future videos. Until then, thank you for watching. Subscribe, come back tomorrow to learn something else. Support this channel on Patreon where you can find additional videos, videos without any ads, and can DM me directly or by joining a channel membership that grants you early access. 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