Why Mice Sing
It turns out that mice are singing all the time, but you can't hear them. Their songs are too high-pitched for human ears. Mouse experts have known for a while that the cutest members of the rodent family emit ultrasonic sounds, but nobody really bothered to listen to them very closely. Then a couple of neurobiologists at Washington University in St. Louis, Timothy E. Holy and Zhongsheng Guo, published a study in PLoS Biology showing that these high-pitched mouse squeaks are actually full-blown mating songs. After analyzing the structure of these songs, Holy and Guo also concluded that there are notable variations in the songs of different mice -- variations that probably go beyond pure randomness. Every mouse sings his own personal tune.
Does this mean that lab mice are singing songs about escaping their cages so they can go hook up with wild mice? No more so than birdsong means birds are lamenting the destruction of the rain forests. But in fact, after lowering the pitch on mouse recordings so they could be heard, Holy and Guo discovered that mouse songs do sound a lot like birdsong. Male mice chirp and whistle when they smell the urine of a female mouse who is ready to mate. And there is no doubt that each mouse has his own way of crafting his song. The researchers conclude, "These results indicate that communication among mice may be more complex than previously appreciated."
I love it when scientists come out with weird comments like that -- prudently understated and yet wildly evocative. The idea that mouse communication might be complex is so fantastic that it makes me wonder whether mice are having conversations with each other all the time that we can't hear. And who wouldn't be charmed by the idea of mouse song "appreciation," as if there were a whole discipline devoted to the aesthetic analysis of mouse noises? Of course, this study makes no such claims. Nobody has discovered a mouse language or culture that's similar to ours.
Holy and Guo do draw one comparison between mouse song and human speech, however. Apparently birds, mice, and humans all produce some of the same molecules in their brains when they sing or speak. This could mean that mouse song and human speech are the results of the same evolutionary process.
If you take a discovery like this out of its direct scientific context, its impact can be understood in two ways. Either mice are a lot more like people than we ever realized, or people are a lot more like mice. There is actually a big difference between those two points of view, and they lead to dramatically different kinds of political choices.
In the first view, in which mice are like humans, we anthropomorphize our little whiskery pals. We imagine that when they're singing their mouse songs, they're full of the same kinds of "complex" feelings and social impulses that we are. Ultimately this view leads to a radical animal liberation perspective, in which a mouse's life is worth as much as a human's. Mice should not be experimented on and coercively bred to grow cancers and such because to do so is as horrifying as if we were doing it to other human beings.
The second view, in which humans are like mice, is far more interesting to me. It leads, I think, to a more progressive political stance and ambiguous moral territory. If human language is at some level equivalent to mouse song, then it forces us to acknowledge how unexceptional we are in nature. Our "language instinct" is just that: an instinct that places us on a level with other creatures ruled by nothing more glamorous than a presence or absence of particular molecules. Realizing this, I think, leads to political awareness about the degree to which some humans treat other humans like mice. Humans experiment on each other all the time, sometimes to the point of grisly death.
But how do we respond in an ethical way to this realization? How do we coexist peacefully with our tuneful, cheese-eating kindred of all species?
Using science to understand other living beings is a good example of what would happen in a world in which people considered themselves just one genetic variation on a theme of carbon-based life. Would that world be one where we'd stop killing mice and each other? Maybe not. After all, there are plenty of animal impulses in us that aren't exactly progressive. Finally we have to pick and choose among our impulses to find out which ones are, to put it in my peculiar human way, "good."
So why is it cool that mice sing? Because humans want to listen to them. That's a good impulse to indulge.