Why are dogs so good at navigating and finding their way around? Is it their sense or smell, or is it that they can sense the earth’s magnetic field? To find out, a team of German scientists recruited dog owners to carefully examine their dogs while they poop. Lu and Tirth discuss this alluring study on S01E08 of the Recreational Science podcast (timecode 8:41):
Lu: Tirth, previously we’ve mentioned how migratory birds can sense the Earth’s magnetic field, which they use to navigate the globe. The question of today’s study is, can dogs sense the Earth’s magnetic field? You’re a man of the dogs, right?
Tirth: Absolutely. It’s better than being a man of the people.
Lu: What do you think the answer is? Can dogs sense the Earth’s magnetic field?
Tirth: No.
Lu: You don’t think so? Dogs are very good at finding their way home.
Tirth: Yeah, it’s the sense of smell though.
Lu: Is it? Well, Tirth, this study that I’m gonna present proves you wrong. The title is “Dogs are Sensitive to Small Variations of the Earth’s Magnetic Field”. It was published in 2013 in the journal Frontiers in Zoology.
Tirth: Great, great journal.
Lu: Yeah, good journal. This is from a group of researchers from Germany. They want to know whether dogs can sense the Earth’s magnetic field. So Tirth, if you were them, what experiment would you perform to answer this question?
Tirth: Actually, I don’t know. Could you put him in like a… You know, in Russia, there’s a city called Magnitogorsk. There’s this giant mountain there full of iron ore, so it has natural magnetic fields.
Lu: Interesting.
Tirth: Maybe we can send dogs on a field trip to Russia.
Lu: And see how they behave in that mountain?
Tirth: See if their heads get stuck to the mountain.
Lu: Ah, I see.
Tirth: Yeah.
Lu: Well, Tirth, that’s ridiculous. The experiment you just proposed is preposterous. Let me tell you how you actually test whether dogs can sense the Earth’s magnetic field, okay? This is serious science: you examine dogs while they defecate, and check to see if their body is aligned with the earth’s magnetic field while they’re defecating. This is the way. This is what you do. This is real science, Tirth.
Tirth: I could never…
Lu: None of your Russian mountain crap, okay?
Tirth: I could never work at this level.
Lu: And look, yes, one of the figures from the study is just a picture of a dog pooping.
Tirth: Actual picture or a cartoon?
Lu: Actual picture. So this German group tested 70 different dogs, 37 breeds, and examined 1,893 defecation events over a period of 2 years. They also examined 5,582 urination events.
Tirth: Wow.
Lu: So they actually found – get this – that dogs prefer to poop with their body aligned along the north-south axis of the Earth, suggesting that they can sense the Earth’s magnetic field.
Tirth: That’s a bit of a stretch though, huh?
Lu: Is it? They found that dogs were almost certain, under specific conditions, – and I’ll get to that in a second – to have their body aligned along the north-south axis. That’s pretty compelling.
Tirth: Well, it’s pretty compelling. I mean, it’s compelling that they align to the north-south axis. Is it possible that they’re actually following some other north-south metric?
Lu: What other north-south metrics are there?
Tirth: Well, at night, there’s a north star.
Lu: Okay, let’s say this is during the day.
Tirth: Maybe something to do with the sun…
Lu: Wait a minute, you think dogs can recognize the north star? Wait, look, maybe you’re right. Maybe you’re right. You should test that, man.
Tirth: We should.
Lu: That could be a Nobel Prize-winning idea.
Tirth: Well, no, no. Okay. So let me propose a semi-serious alternate explanation of this. Maybe it’s got something to do with the layout of the houses in Germany. Maybe the way the yards or the outdoors are oriented that they happen to be more so oriented along the north-south axis.
Lu: Well, that’s an interesting thought, but get this: I said earlier that dogs only align their bodies north-south under certain specific conditions.
Tirth: Right, right.
Lu: And those conditions are when the Earth’s magnetic field is stable. When the magnetic field is unstable, they don’t necessarily align north-south. This strongly suggests that they are actually detecting the magnetic field and not some other north-south metric.
Tirth: And they’re measuring the stability by like, magnetometers or something?
Lu: Yes, and this is a little bit detailed, but it’s very interesting. The magnetic north, the direction a compass will point to, is not necessarily aligned with the actual north, the North Pole.
Tirth: That’s correct.
Lu: There is a difference, and that difference is called the magnetic declination. Which itself changes over time due to the dynamic nature of the Earth’s magnetic field, which is just constantly shifting a little bit.
Tirth: Yeah, they think that it’s actually going to flip over in like a thousand years or something…
Lu: The key point here is, sometimes the Earth’s magnetic field is stable, so the declination remains unchanged. When that happens, the dogs almost always align their bodies north-south when they’re pooping. When there is as little as 1% change in the declination, meaning a tiny bit of instability in the Earth’s magnetic field, the dogs don’t align, which is very impressive. So, you’re wrong, Tirth, you’re a man of the dogs, but you underestimated the dogs and their magnetic ability.
Tirth: I was just giving their sense of smell greater credit. Hey, do they speculate why dogs have this sense?
Lu: Beautiful question.
Tirth: Thank you.
Lu: So the idea is maybe the ability to sense the Earth’s magnetic field helps dogs to navigate. But maybe an even better question is why do dogs align their bodies when they’re pooping?
Tirth: Yeah, that’s true, I didn’t even think of that.
Lu: Why don’t you ask me that?
Tirth: Why do they align their bodies to the north-south axis while they’re pooping, specifically when they’re pooping?
Lu: Brilliant question, Tirth. Once again, brilliant question.
Tirth: Thank you.
Lu: We don’t know for sure, but the researchers have a hypothesis. I think it’s a very compelling hypothesis. They think that maybe dogs need to calibrate themselves once in a while to the magnetic field.
Tirth: What, like robots? Like they’re androids?
Lu: Well, it’s like if you’re going on a hike, maybe you want to read the map once in a while so you don’t get lost. That’s the analogy. And the reason dogs only align their bodies when the Earth’s magnetic field is stable is because that’s when they can get good, accurate information. If they were to align their bodies when the Earth’s magnetic field is unstable, that would be akin to reading a blurred map. It wouldn’t be that helpful.
Tirth: No, not that helpful.
Lu: Pretty compelling, right?
Tirth: Yeah, but why do they only do this when they’re pooping though?
Lu: Great question. Beautiful question.
Tirth: Oh, thank you.
Lu: Tirth, as you know, dogs are very economical creatures.
Tirth: Is that right?
Lu: There’s nothing dogs hate more than wasting time, is that right?
Tirth: I don’t know what kind of dogs you’re hanging around, man.
Lu: You’re a man of the dogs.
Tirth: I am a man of the dogs.
Lu: Dogs love three things: Manspreading on couches, we talked about that last week.
Tirth: Yeah, they love it.
Lu: Chasing squirrels.
Tirth: Yes.
Lu: And spending time wisely.
Tirth: Wisely, yes.
Lu: They love those three things.
Tirth: Yes.
Lu: They don’t waste time. We all know this. They want to kill two birds with one stone.
Tirth: Literally, sometimes, yeah.
Lu: When they’re pooping, they don’t want to waste that time. They want to be doing something productive during that time.
Tirth: This is like when you’re on the toilet and on your phone.
Lu: Yes, exactly.
Article citation
Hart et al., 2013. Dogs are sensitive to small variations of the Earth’s magnetic field. Frontiers in Zoology. https://frontiersinzoology.biomedcentral.com/articles/10.1186/1742-9994-10-80
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