Ever wonder why dogs need to get themselves into just the right position to do their business? As it turns out, dogs align their body axis according to Earth’s magnetic field when they squat to poop—a behavior that changes when the magnetic field is unstable. But why do they do it?
The results of this recently published paper from Frontiers in Zoology sound goofy, but the takeaway is all in the title, “Dogs are sensitive to small variations of the Earth’s magnetic field.” The researchers measured the direction of the body axis of 70 different dogs while they were off-leash during 1,893 acts of defecation and 5,582 acts of urination over a two-year period. They found that, under calm magnetic field conditions, dogs prefer to orient their bodies along the North-South axis when they poop. However, this behavior did not occur during unstable magnetic field conditions, and the best predictor for this change of behavior was the rate of change of magnetic declination. This means that the dogs are responding to changes in the polarity of the magnetic field rather than changes in intensity. It’s that change in behavior that has the authors of this paper particularly excited, since it’s the first time, according to the paper, that magnetic sensitivity has been proven in dogs and that a predictable behavioral reaction from natural magnetic field fluctuations has been unambiguously observed in mammals.
The question that this inevitably invites is: why on Earth do dogs do this? The paper notes that it’s not just that dogs prefer to align themselves along the North-South axis; they also seem to avoid the East-West axis when they poop, although it’s not clear whether they do so consciously. The researchers suggest that perhaps, when dogs poop, they are also taking the opportunity to orient themselves:
An answer may lie in the biological meaning of the behavior: if dogs would use a visual (radical-pair based) magnetic map to aid general orientation in space as has been proposed for rodents , they might have the need to center/calibrate the map now and then with regard to landmarks or a magnetic reference. Aligning the map and the view towards North (or South) facilitates reading the map. Furthermore, calibration only makes sense when the reference is stable and reliable. We might think of this the same way as a human is stopping during a hike to read a map. When the map is blurred or the reference (perceived magnetic direction) is dispersed or moving due to magnetic disturbances, however, calibration is impossible. In the case of the dogs it thus would totally make sense to not pay attention to magnetic body alignment any more under conditions of a shifting magnetic field.