Six limbs

Today I saw a wonderful talk about how the anatomical structure of the dragons in the animated Dreamworks film “How to Train your Dragon”. The talk was given by Stuart Sumida, who is a paleontologist and anatomy specialist. Animation studios turn to him when faced with tough questions like how to design a plausible dragon.

The last question from the audience was about whether there are any animals in real life with both wings and four legs (like the dragon Toothless in the film). Dr. Sumida first pointed out that the answer is certainly yes, in the insect world. But in the world of mammals and their cousins (like birds and pterodactyls) the answer is no. Wings are an adaptation of forelimbs. So birds, bats and pterosaurs all have just two wings and two hindlegs. All winged vertebrates evolved as variations of the same four limbed structure.

At which point it occurred to me, why don’t we see dragons as monstrous, the way we see, say, space aliens? After all, dragons like Toothless breaking one of the fundamental constraints of creatures near to us in the evolutionary graph — that they have four limbs:

Dragons are not the only example of this. We don’t run screaming from pictures of Pegasus, the winged horse from Greek mythology:

Similarly, most people find centaurs to be distinctly attractive. Heroic even:

So what’s going on here? Logic tells me that anything with six limbs growing out of its spinal cord should fall squarely into Freud’s theory of the uncanny. It should freak the hell out of us. And yet we are charmed by distinctly the unatomical bodies of our various mythical six limbed friends.

I find this very mysterious.