P.Z. has his cephalopods, so, as an ailurophile, I’m gonna have my CATS! But with a dose of science. It is still a great mystery exactly how cats produce their purr. When I was younger I dreamed of solving this question and publishing a paper in Nature called simply “How cats purr.” But the experiments always involved a cat trained to purr on cue, coupled with some gruesome cutting experiments. Now it might be possible with MRIs—if they can be given to moving objects.