How do dogs walk?

How do dogs walk? No, that's not a joke. It seems that as a nation we are all misled in how we think dogs, horses and all other four-legged creatures move their legs because half of the time we get it wrong. And that goes not just for toy makers and cartoonists but even for the folk at natural history museums, taxidermists and the authors of scientific text books...

This astonishing fact was the discovery of Gábor Horváth of Eötvös University in Hungary and his colleagues who carried out what sounds like a rather fun study. To collect data for their paper which was published this week in the journal Current Biology, the team of researchers went round museums hunted through books and visited toy shops, gathering together over 300 depictions of four-legged animals while they are walking. This included horses, zebra, donkeys, deer, okapi and all sorts of exotic antelopes.

They found that in over half of these depictions, the animals were shown with their legs in the wrong place, because the truth is they should all have been the same. It's been known for over 100 years now that all quadrupeds walk with the same sequence of leg movements; they step with their left hind leg, followed by their left foreleg, then their right hind leg and finally right foreleg and so on. The only difference between species is the timing of that stepping.

The reason that all four-legged mammals walk this way is because it minimises the chances that they will fall over. When they are walking slowly they always have three feet on the ground at one time which form a stable triangle.

So, it is rather odd that toy animals are often made the wrong way because it means the toys are more likely to topple over than if they were portrayed the right way.

The reason we all get it wrong is probably down to laziness, and also perhaps self reinforcement: there are so many wrong depictions of horses and dogs walking out there, in museums and on the internet, no wonder half the time we get it wrong.

One place where quadruped walking is almost always right, though, is in Hollywood. The depiction of horses, elephants, dinosaurs and other four legged creatures walking through movies is almost always right, probably because these days, computer animators rely heavily on advice from experts in biomechanics and animal locomotion to make sure they hit on an authentic look.