Now we ponder... why does a dog prefer the N-S axis of the Earth when toileting? Scientists are still stumped on this. According to co-author Dr Sabine Begall, "We can only speculate. Since it is the polarity that has an effect on the alignment direction, it could be that the dogs somehow calibrate their compass or read their 'mental map' during the walks." Reasonable enough justification but I believe the majority (including ourselves) are still waiting for further investigation into this matter.
All in all, we do appreciate these Scientists efforts at trying to figure out our dogs quirky behaviour when it comes to their toilet rituals. I guess our dogs just want to make entirely sure that they are indeed in alignment with the Earth's N-S axis! It could be considered a load of bullocks but who knows... there may be a hint of truth to it.