If I've got it right (and chances are good that I don't), mirror neurons are neurons that fire in response to actions observed by others instead of the individual self. We see someone flinch when they get a paper cut and we instinctively flinch, too - those are the mirror neurons firing. Watching someone yawn makes us want to yawn - mirror neurons. They were first discovered in monkeys when it was noticed during brain scans that certain neurons in their brains were firing in the exact same manner as the other monkeys they were observing doing other activities. It's been hypothesized that mirror neurons are the basis of empathy ("I feel your pain") and possibly even ego-consciousness when we create mental models of an "us" that can feel the same thing as the "them" that we're observing.
So humans and other primates have mirror neurons, but do other animals, such as cats? I could see how having mirror neurons would be an evolutionary disadvantage for a hunter/predator (the last thing you need for survival is empathy for the prey), but we humans are apparently capable of ignoring our mirror neurons as we inflict great suffering on animals (just visit a slaughterhouse and see), so it shouldn't be surprising that animals can also ignore the signals fired by the mirror neurons when it's in their survival interests.
Two recent episodes have suggested to me that cats do indeed have mirror neurons. First, Eliot recently contracted fleas from some source (probably something I dragged into the house, as he's now a totally indoor pet). Part of his cure, the part he really hated even more than having pills forced down his throat, were his flea baths. As everyone knows, cats don't like getting wet and when I had to dip him in a kitchen sink full of pleasantly warm water (at least to my senses - cats may perceive temperature differently than we do and how would we know?), he fought like a, well, wildcat. He twisted and squirmed and tried to get away and while he didn't lash out at me directly, I still wound up with some scratches and cuts on my arms. He also howled and eventually hit the most chilling, blood-curdling sound a cat could possibly make, one I never heard from him before, and his brother cat Izzy, who was watching all this, almost immediately emitted the same horrid tone, suggesting a shared response to what he was seeing and hearing. Was this mirror neurons?
People say that cats don't care what happens to human people around them, and I've seen cartoons of cats just watching or grooming themselves while their human companions were, say, choking on a chicken bone or getting mugged by an intruder. But last weekend, as I was walking out of the bathroom after a shower, I slipped on the wet floor and fell - hard - backwards onto my ass. I was lucky I didn't hit my head on anything or break any bones, but it did jostle me pretty hard as I landed with a loud thud. I don't recall, but I probably was making that "whoa" sound and an expletive or two might have been expressed.
The cats were sitting on the kitchen counter waiting for me to come out of the bathroom and saw the whole thing. As I slowly got back up, I saw them staring at me with saucer eyes almost bugging out of their heads - I've never seen a look like that on them or any cat before. They clearly were concerned and not a little shaken up themselves by what they saw just happen to me. Was this also the firing of mirror neurons?
Of course, I googled the answer to my question "Do cats have mirror neurons" before composing this post, and the science seems to be "maybe." Monkeys certainly do as demonstrated by brain scan experiments. Ethically, we can't perform the same brain scan experiments on humans, but based on behavioral studies, the answer seems to be "yes," and besides, we're primates, too, so why should we be different? Dogs apparently have them, too, and some articles state that cats do as well, but don't indicate the basis for their conclusion (neurology? behavioral studies? mere assumption?). My limited research, based on flea bath and falls, seems to indicate that yes, they do, but I'm not about to see if I get the same results by repeating my little experiment and falling on my ass again.
That part hurt.