Cat and mouse and us

The Hemodynamic Cat battling a swinging light switch, photos by Ms. Dr. Hemodynamics; the HC in a quiet time.

Recently, the Hemodynamic Cat did something surprising: she caught a mouse.

I would like to say that I have never doubted the Hemodynamic Cat's mouse-catching abilities, but this is not the case. She spends a lot of time pouncing on and batting around her toy mice, in a way that suggests some inner ferocity. But her record on watching cockroaches with interest rather than hitting them, and her failure to show any evidence of actual mouse-catching, left me a little skeptical. I've come to love the HC for other reasons.

Recently, I was coming to bed and saw that the HC had a mouse in front of her, and was looking up at me expectantly, as she sometimes does when she wants me to play with her and her toy mice. Then I looked more closely and saw that it was too thin and small to be one of her toys; and that in fact it was breathing.

My experiences in an immunology lab left me well-prepared for this moment; I picked up the mouse by its tail, and eventually delivered it to a warm spot outside our apartment where I hoped it might be able to recover and go on living outside our apartment. It wasn't moving much, and I thought about more definitively snapping its neck--to finish the job that the HC had clearly started and end its suffering--but I wasn't sure that it might not be able to rally once no longer stressed and stunned, so I left it. I later found it definitively dead, in the same spot. The HC had killed the mouse.

I know that some cat owners think that the cat's habit of bringing dispatched prey to display to their owner is some outgrowth of wild cat mothering habits. In terms of the original wiring for the behavior, that's probably true--there has to be some "little tasty things I don't eat right away" circuit available to build on. But the wild forebears of domestic dogs also feed their puppies, and domestic dogs don't make a point of sharing their catch with their people in the same way that cats do.

I've always thought that this behavior is actually part of the social contract that cats and people developed with the origins of agricultural society. Recent genetic work confirms what can be surmised from history, archaeology, and anthropology: cats go with agriculture, not with hunting and gathering. When people started having grain silos, field mice started becoming silo mice, moving to where the concentrated bounty of the fields were stored. Cats followed the mice.

This seems like the moment in which the "show the mice" strategy would have been most useful. The social bond would not have come first, and so the showing of the mice is not a process of mistaking people for kittens. It is an act of seeking patronage. A cat who just seemed to wander around the village but did not show the mice she caught to anyone might be tolerated or even enjoyed. But I'm not sure that early agrarian societies would have put much energy into caring for that cat.

On the other hand, the cat who comes to the peasant farmer, drops mice at the door, and meows loudly with enthusiasm, is saying, "I am worth keeping around." What the cat loses in protein from the mouse not eaten, she gains in protein from the people who want to encourage her mouse-killing. People, and especially grain-farming people, want cats to kill many more mice than they need to support themselves; they want cats to kill every mouse in sight. The cat that brings mice is showing her dedication to this shared mission. The cats that are also social and charming get to live inside and sleep next to the warm bodies of the giant primates, but the "show the mouse" strategy might well have been the first step in the evolution of cat domestication.

Cat experts sometimes say that cats, unlike other domestic animals, domesticated themselves. This explains their more ambivalent attitude about human attention; cats have eliminated only the wildness that kept them out of the house, and sometimes not even that. The Hemodynamic Cat, her ancestors having been bred for the company of princesses, is an extremely social creature with the people she knows, but she still has a wariness of new people that shows the not-so-ancient wild cat inside her.

As I held the mouse by its tail, its lungs expanded and contracted and its little legs kicked. In retrospect, given that the mouse could not get up and walk anywhere after I set it down, I think the legs kicking might have been a lower spinal cord reflex arc. Maybe if something grabs a mouse's tail there is no need to wait for the brain to tell the leg muscles to start making running motions; but the mouse needs the brain to communicate with the spinal cord in order to coordinate its movements. A mouse is a tiny thing, but with all the wonder of mammalian evolution, and of its own special qualities. From scores of dissections, I could imagine its heart; its thin, wide diaphragm; and, as I found again and again in the lab, its comparatively large spleen, full of blood and immune cells. I didn't want to touch its fur--I didn't want to give it a chance to turn and bite me--but I could remember what touching a mouse felt like, the warm softness of it, the vitality of the quick-moving lungs and heart. The mouse was beautiful, as all mice are, and I mourned its demise.

Still, I don't want mice eating our food and having the run of our house. And so when the Hemodynamic Cat looked up at me, with the little gray field mouse breathing but laying still in front of her, I saw our cat with a new respect, and felt something ancient: our cat was earning her keep.

Our social contract forged between two species, once seemingly consisting only of bonds of affection, had renewed its ancient preamble. I had thought that I loved the Hemodynamic Cat for her inherent value as a creature, and for her love of us, whether or not she caught mice. As I took the mouse out of the apartment, I realized that I now not only loved her, but respected her in a new way. Good job, I told the Hemodynamic Cat, and she said, "Mrowww!" back. I had killed mice for science. The Hemodynamic Cat had done something much more intimate and powerful: she killed a mouse for us.