If you’re out of ideas for a conversation over family dinner tonight, try this (it works better if you have a four-legged pet): how do cats and dogs walk? That is, in what order do the four legs take steps?
If your family is like most of us—and “us” includes, somewhat appallingly, illustrators for veterinary anatomy books as well as toy designers and the curators who put together dioramas at natural history museums—they’ll get it wrong. According to a sobering little paper in the January 27 issue of Current Biology, both laymen and people who should know better get the walking gait of horses and other quadrupeds (something Eadweard Muybridge documented and published in the 1880s; the Wikipedia entry has nice videos) wrong about half the time.
The study, led by Gábor Horváth and György Kriska of Eötvös University in Hungary, explains why model horses fall over so often. They’re typically depicted in stride, but the wrong stride; horses, dogs, cats et al. ambulate the way they do because it provides the greatest stability. If a quadruped walked any other way, it would tip over . . . as model horses tend to.
And now the answer: in all four-legged animals, the order is: left hind leg, left foreleg, right hind leg, right foreleg. Repeat. Any leg can take the first step, but once it does the sequence is that above.
Oh, and while illustrators and museums and toy designers mess up, Jurassic Park and The Lord of the Rings got the gaits of dinosaurs, elephants and fantasy beasts exactly right.