“Are You a Man or a Mouse?”

The photo in a recent newspaper was eye-catching. A plump mouse was standing up on its hind legs, either whispering into or about to nibble on the ear of—a cat. The cat was looking off into the distance, wearing the detached expression of someone undergoing an invasively intimate medical procedure. It seemed to be trying to pretend the whole humiliating episode was simply not happening.

The accompanying AP article described a research project in which a group of Japanese scientists used genetic engineering to wipe out mice’s natural fear of cats. Instead of fleeing or cowering at the sight or smell of felines, the altered mice approached, snuggled with, and tried to play with the cats who were their companions in science.

The researchers said the cats they used were domestic and docile. Presumably, they were also well-fed. There was nothing in the article about the percentage of fearless mice who failed to survive the experiments.

According to the newspaper article, this research shows that fear is genetically hardwired in the brain rather than learned from frightening experiences. Personally, I think it’s more reasonable to conclude that fear can come from both sources. If you’re interested in finding out more about the fearless-mouse project, the study was published in the November 8, 2007, issue of Nature magazine.

The really significant issue related to this research, however, is much more serious. The big question is whether we—in our work places, our schools, our public buildings, and, above all, the sanctity of our homes—are prepared to cope with fearless mice.

Last fall our house suffered an invasion of the furry little varmints. We were first alerted to their presence early one morning, when I heard suspicious rustling noises in the kitchen. I knew it wasn’t my spouse filching from my hoard of chocolate. For one thing, he was still innocently tucked into bed. Besides, I know better than to keep my stash in a place as obvious as the kitchen.

Investigation revealed a disturbing amount of mouse-related evidence in one of the kitchen cupboards. We set traps, washed pots and pans, and tried not to think about the Hanta virus as we scrubbed out cupboards with bleach. After a couple of our uninvited guests succumbed to traps baited with peanut butter, and after we covered the holes they had used, we went back to a mouse-free lifestyle.

A few weeks later, rearranging furniture, I moved our rowing machine. Part of its frame consists of a hollow steel tube about an inch and a half in diameter, with an open top about 18 inches off the floor. That tube was filled with some 20 unshelled pecans. One of our enterprising little invaders had decided this would be the perfect spot for a hoard.

To get each pecan into the cache, the mouse first had to haul it out of a plastic bag inside a cardboard box, then transport it halfway across a large room. Then it had to hop up onto the base of the machine, climb a fairly steep incline, jump across to another slanted piece of the frame, climb that, then jump down to the edge of the open tube—all the while carrying a pecan almost half its own size. It made this journey at least 20 times, not counting any extra trips due to slipping, falling, or dropping its cargo.

When a critter is blessed with this kind of agility and persistence, it has enough going for it. It doesn’t need reckless courage as well.

Creating mice who don’t hesitate to cozy up to cats in controlled laboratory conditions is bad enough. But think of the possible consequences if they escaped to terrorize the outside world. You innocently open a kitchen drawer, and there stands a defiant mouse, waving a small red flag and squeaking, “Down with the cat-lovers!” It is wearing a tiny tee-shirt bearing the slogan: “Revenge of The Hanta Hordes!”

We have to stop these researchers now. Let’s keep the world safe from rodent rage.