Animal Pests Are All About Perception

Bethany Brookshire’s new book explores what separates a pest from the rest.

The following is an excerpt from Pests: How Humans Create Animal Villains by Bethany Brookshire.

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Pests: How Humans Create Animal Villains


I spent my formative years in a lab studying mice. I was researching the effects of drugs on the brain— from stimulants like cocaine to antidepressants and hallucinogens. I was trying, in the small, creeping millimeters of scientific publications, to work out the pathways in our heads, the electrical firings and misfirings, that give us pleasure and pain, ecstasy and misery.

It takes only days in biomedical research to learn to have your key card in easy reach at all times. Attached to a little extender on my pocket or belt, or hooked to a lanyard, my dorky little card was sure to add a jarring note to every outfit. But I needed my nerd cred, first to get in the front door and past the security guard and then to get into the hallway leading to the offices. Then again into a bright, white room humming with equipment. Some of the whiteness came from the floor, some from the walls, and some from the clean bench paper carefully taped to every horizontal surface.

Several times a day, I’d head past loudly humming freezers and put on a blue disposable lab coat with a white collar and cuffs and white plastic snaps. Not just for the protection— lab coats have lots of pockets. I’d wriggle my hands into nitrile gloves with a practiced twist. (Snapping gloves is for amateurs. Slide, then twist). I’d add a pair of protective booties over always, always closed-toe shoes.

Another key card entry, another pair of booties slipped over the first pair. A hairnet, a surgical mask. A final key card entry into a long, gray hallway with the constant tang of 70 percent ethanol cleaning fluid. It was easy to miss the slightly downward slope as I walked through the building. Once in the windowless hallway, though, the subterranean feeling became obvious. Under fluorescent lights, past rolling carts, and through a heavy metal door. The room was always dim, filled with steel racks and plastic cages, with a constant dry, rustling, scuttling sound in the background. I’d breathe in the dusty, earthy smell of corncob, wheat, and a little bit of pee.

It smelled like home.

I love mice. The feel of their tiny little claws as they climb over my hand. The soft fur and tiny tummies. The bright eyes and whiskers that flare forward enthusiastically when they get treats. Once, two colleagues caught me working with my mice on the weekend— and singing to them. I especially loved to give them Froot Loops. Watching a mouse eat a Froot Loop was like watching a human try to eat a car tire. They’d roll it around, nibbling away at the edges, finally breaking through and devouring the center. Then they’d flop out in the cage to sleep it off. No regrets.

They were mice, sure. But a lab mouse in a cage— beyond the same rough size, soft fur, and shining eyes— bears little resemblance to the mice that plagued the cabin of my friend Eva.

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Eva is a journalist who had brought her family over from Germany for a yearlong fellowship at MIT in 2019. In March 2020, she found herself trapped in a two- bedroom apartment in Cambridge with her husband and three kids, who could no longer go to school due to the COVID-19 pandemic. Desperate to find a little breathing room, Eva and Stefan crammed the kids into a rental car and drove to a cabin in western Virginia.

The mice were there to greet them, and only too happy to savor Eva’s professional- level sourdough bread. Soon, she was texting me pictures of nibbled loaves and the mini poops of mice on the cabin’s kitchen table. Worried about hantavirus, the family put all their food in the oven. It didn’t work. The mice slid right in. The only safe spot turned out to be the microwave, stuffed every night with as much food as it could hold.

Both of these places— a cabin in the woods and a sterile laboratory— offer a niche that mice have filled. One is as old as our first attempts at civilization. Humans have had house mice since we had houses, and we’ve been leaping on chairs to get away from them probably ever since we had chairs to leap on. In the pest niche, mice make a living off our leavings— a living so successful they’ve spread across the world.

But the other niche— the lab niche— is relatively new. Here, the mouse isn’t a pest. Instead of living off us, we are living longer and healthier lives off them. We thrive from the data mice produce and the lessons they can teach us. As living laboratory tools, mice don’t just advance our knowledge; they change science itself— molding what questions we ask and how we look for the answers.
And yet, that new niche would never have been possible without the old. First, the mouse had to live among us. It had to become a constant in the human landscape. It became both so common as to seem worthless and invasive enough to be a constant minor irritation.
A mouse isn’t a human. But it lives in the human world and eats human food. It navigates life with a mammalian brain, with a physiology very like our own. It’s something we recognize as clever, and even cute— but which many people would kill without a second thought. And so, when we went to look for something to stand in for us as we learned the secrets of our bodies, something living but not too lovable, the mouse was a natural choice. Just human enough to be not human at all.

Excerpt from Pests: How Humans Create Animal Villains by Bethany Brookshire. Copyright © 2022 by Bethany Brookshire. Reprinted by permission of Ecco, an imprint of HarperCollins Publishers.

Meet the Writer

About Bethany Brookshire

Bethany Brookshire is a science journalist and author of Pests: How Humans Create Animal Villains. She’s from the D.C. area.

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