With billions of mice in the world today, these creatures are hardly an endangered species by anyone's reckoning. They share our habitats, living successfully in our homes and our laboratories. We've domesticated them and we also let them go wild around us. We fear them and we sentimentalize them. They can be a royal pain in the neck and also cute as hell.
It's not customary for adults to get attached to mice; that's usually kids' business, assuming anybody wants the job. I held a funeral for a mouse today. It wasn't a religious affair since I don't believe in an afterlife, although you'd have an easier time convincing me there's a heaven for mice than one for humans.
But that's not what this is about. I just wanted to take a moment to reflect about this little guy and why I felt so much for him. He died at the ripe old age of, maybe, eight days. I'd known him (I'm assuming he was a male although I never knew for sure) for exactly two days when he died. It's not like his death surprised me. I did everything I knew to forestall it, but the cards were just stacked against the two of us. That still didn't make it any easier.
We met on Sunday afternoon, around 4 PM. I came home from a champagne birthday brunch feeling pretty mellow and a year older. I noticed a leaf on the living room floor and went to scoop it up, crumple it and throw it out, all in one deft movement. At the last possible second the leaf moved. I'm glad I have the perceptual circuit in my brain that says "Leaves don't move like that." It froze me in my tracks. If this had been anything resembling an adult mouse, it would have scampered across the floor and into the next county before I could lean over to get a better look. But this was far from an adult.
The mouse was barely an inch long and his head looked too big for his body. Walking, not to mention scampering and jumping, were at least a week away. I picked him up carefully, fearing the occasional bites I had received in past encounters with wild deer mice (Peromyscus maniculatus). I needn't have worried. This little guy didn't have teeth yet.
I wondered where in the world he had come from. It's a cinch he was born in my house, but why would his mother have abandoned him at such an early stage of development? Unfortunately, I had a pretty good idea of the answer. A day earlier I had live trapped two adult deer mice and let them go about a mile away. They had been leaving a mess in my kitchen (they are known as "commensal animals," after all) and were getting into a large sack of sunflower seeds I had bought for the Fall. It never occurred to me that one of them might have been a nursing female with a brood stashed somewhere in my house.
This baby had just about every feature you'll find in a textbook example of a neonatal animal. The only thing missing was the big eyes looking up at me imploringly. His eyes hadn't opened yet, but it hardly mattered. His mouth was agape like a baby bird's. His front paws groped for mama's chest. He convulsed in uncoordinated movements designed to keep him warm and fed. It's not very manly to admit, but if I could have nursed him, I think I would have done it right there, on the spot.
How long had he been wandering around blindly? When had he last eaten or felt the warmth of his siblings? I picked him up and quickly put some warm water on my finger tips. He licked it hungrily. It was amazing to watch, and I knew in that moment I had taken full responsibility for the life and well-being of this baby animal.
It was a costly decision. He would not have become a cherished companion even if I had succeeded in keeping him alive - and that would have been a long shot at best. Deer mice are small and cute but they are not domesticated. Millions of years of natural selection have shaped them to be a prey species and they have the emotional and behavioral repertoires that go with the package. When you're a prey animal, you don't embrace the world with open arms. Chances are, that big thing out there views you as a pest or as a meal.
Here's what would probably have happened to my mouse and me, had I succeeded in nurturing him into adolescence or adulthood. He would have changed radically and rather quickly, and I would have had to let him go. I speak from experience. Wild mice do not become pets. They do not welcome the companionship of humans, no matter what you've done for them as helpless infants. The best I could have hoped for was his survival and successful release.
If you want to see how strongly many of us harbor fantasies about befriending wild animals, check out the video on YouTube about the lion recognizing and hugging the woman who saved it from starvation six years earlier. But that was a lion and this was a mouse - a big difference as far as natural selection goes. The possibilities here were, to put it mildly, limited. But I still wanted him to survive, and I wanted my help to have been part of it.
Sometimes it's tough to be what they call a population biologist. You have to remember that the survival rate among wild mice is startlingly low. There's a reason those litter sizes are so large (a dozen is not uncommon). If even a quarter of them survived for six months, the world would be overrun with deer mice. We need, in fact they need the survival rate to be so low. But that doesn't keep us from getting involved with individual cases.
Humans have some powerful circuitry that makes us want to nurture. Evolutionary psychologists have argued that those mental programs aren't always too fussy about which species we're nurturing. You can probably understand why that is. Nurturance is essential to the survival of our species. It's far better that our care-giving be overextended or triggered by non-humans, than not triggered easily enough. Natural selection would have seen to that, and the results are clear. Some reliable sources estimate about 500 million pets in American homes (almost twice the human population), ranging from fish, reptiles and birds to rodents, dogs and cats. It's a rare person who can leave an orphaned baby animal crying by the roadside. My investment in this pup was pretty strong even though I only knew him for two days. I can assure you I wasn't in the best of moods the day he died in my hand.
There's a paradox here and it tells you something about how we humans come wired. Many of us who'd stop and make coo-cooing noises over this helpless little mouse pup, and maybe even help me trying to nurse him to survival, wouldn't think twice about luring him into a snap trap once he approached adulthood. From parent to executioner: it sounds like a contradiction, but these are entirely different circuits and they both make good evolutionary sense.
This pup didn't get a long look at the world. In fact, with his eyes still shut, he didn't get any look at it. Here for about a week, a normal start that was abruptly ended, and then some very odd experiences, including a few tastes of diluted cream and some strawberry Ensure on a Q-tip. Then it was over. Too many events that his barely developed body wasn't designed to handle.
I'm sure it happens all the time (minus the part about the strawberry Ensure). But there's one big difference here. This little Deer mouse pup will be remembered and he will be missed. That, too, is part of being human.
Illustration by: Athena Gubbe
Read more about what Evolutionary Psychology has to say about pets in John Archer, Why do people love their pets? Evolution and Human Behavior (1997), 18, 237-260.