In the seventies, over a period of five years, I killed approximately two thousand rats. That’s four hundred rats per year, a little over a rat a day. I was a graduate student in cell physiology, studying the effects of lead poisoning on liver and kidney biochemistry. At the time, I said, “I have to kill rats to get a Ph.D.”

My husband said, “Everyone has his rats.”

My rats were lab rats — white and pink-eyed, and passive and stupid from having led sheltered lives in the commercial breeding outfit that supplied them to the likes of me. Lab rats come in different, specific strains to ensure genetic purity and reduce variability in research results. The breeds have mysterious names like “Sprague-Dawley” and “Charles River.” Each group I worked with contained six male Sprague-Dawley rats in one cage: either six “experimental” rats that ate food laced with lead, or six lucky “control” rats that chomped on normal rat chow. Each experiment lasted four weeks, at the end of which time I killed them.

I had a number of overlapping experiments, so I was forced to keep up a fairly constant killing schedule. We couldn’t use lethal injection because chemicals would immediately alter the rats’ metabolism, so we decapitated them. We used a small guillotine that sat in an aluminum tray on a cart. We would move the tray and guillotine to our desks, which were covered with brown butcher paper that we changed when it got too messy. The guillotine had a head hole and a handle that pushed down the blade with a motion similar to a fast, emphatic slicing of bread. I would grasp the rat around his upper body with my left hand, holding his front feet against his belly so they wouldn’t be cut off with his head. (It was bad form to cut off their hands.) Then I would jam his head through the hole, making sure his neck was positioned on the edge of the blade, and, watching my fingers, whip down the handle with my right hand. (It was also bad form to cut off their faces and noses because you had mispositioned them.)

With practice, it was easy to kill them right. It took about ten seconds from the cage to death, once you got good at it. After decapitation, I’d hold the rat’s headless body over the tray while he flailed and bled, splattering blood on my lab coat and the butcher paper. Sometimes I’d get scratches on my wrists from his nails kicking against me; usually, the marks would disappear by the next day. When he was still, I’d cut open the rat and remove various organs and place them on ice, then throw his body into a black plastic bag. My hands would be covered with fur and blood and excrement — and, I imagined, the smell of fear and betrayal. I’d wash the guillotine and tray in the sink and place it back on the cart, sparkling clean. About every ten rats I’d have to change the brown paper on my desk.

At first, we grad students were a bit squeamish about killing rats, but we all learned how to do it. I watched several rat executions before performing my first one alone in the lab one morning at six. I rehearsed it in my mind for forty-five minutes, then did it quickly and perfectly. Afterward, I sat down for another forty-five minutes to cool off. Even after I got used to it, I still liked to do my killing alone, early in the morning; it made the rest of the day easier.

I got good at killing rats. Only once did I make a mistake. Overconfident and careless, I failed to stick his head in far enough, and so cut off his nose. He started spurting blood and screaming. In a frenzy, I grabbed him by the tail with both hands, swung him around in an arc, and slammed him down on the table. I did this several times. Then I sat down for a while.

When I was new at the lab, a student who was just finishing up told me he expected to be followed for the rest of his life by a line of white rats demanding an explanation. The other graduate students in the lab didn’t like rats and were bitten occasionally and had to go to Student Health for tetanus shots. It was a war between them and the rats. Sometimes I would get their rats out of the cages for them because they were afraid of being bitten. But in all my years of rat research I was never bitten. People said, “You know how to handle rats.” It was true.

I fed and watered my rats every day. I would stick my hand into their cages to let them sniff me, which they liked to do because they are curious creatures. It was easy to touch them. Rats are warm and quivering and sensitive, and they like walking around on your shoulders and sniffing in your ears. They would sit on their haunches and gently touch my hair and ear lobes with their fingers, then scramble up to the top of my head and down my arms. Even at that time — before studies showed how touch can alter physiology — I knew that it was probably not good scientific practice to handle the animals except to remove them at the end of the experiment. But I assured myself that I spent as much time with the control rats as with the experimentals, thus canceling out any variables that might be introduced. I’d sit on the cement floor of the animal room and hold a bunch of them in the lap of my lab coat, where I’d play with them. Sometimes they’d wander onto the floor, but they’d eventually come back to my lap because it was warm and all their brothers were there. Some were more aggressive and curious than others. These would always want to slip into my sleeve and investigate.

I did this more than I care to admit. I liked being alone with the rats in the animal room. It was peaceful and quiet and cool. Few people came in there, and I was never caught in my scientific shame. My rats gave me solace, which made it easier for me to go on killing them and thus survive graduate school. I tried to liken our strange situation to the buffalo forgiving the Indian — granting absolution because they were both part of a larger spiritual scheme — but this gave me no comfort. It still doesn’t. What did comfort me was their breath and their whiskers and their beating hearts and their warm bodies as they delicately picked their way over me.

Frank was the head of the lab, and my advisor. He was straight talking and good-hearted, married with two kids, and, from what I understood, at one time he had been actively involved in the lab. I also heard he had been pudgy and a terrible dresser until a few years back when he had taken up with a graduate student in the lab who’d helped him clean up his act. The graduate student was now his postdoctoral assistant, and she was really in charge. Her name was Elizabeth. She spent a lot of time on her appearance, and it was obvious she had been a good influence in sprucing up Frank. But she was aloof and snide and brittle toward me and the other graduate students. She shook hands by extending the tips of her fingers to be gratefully touched. Frank warmly called her Lizzie. We called her “the princess.” Since he spent most of his time in her office with the door closed, we would knock when we needed to see him or when there was a phone call. Eventually, we stopped asking for anything and stopped answering the phone.

If any grant money was available, it would go to Elizabeth’s research, which other people did for her. Her name appeared on all the papers that came out of the lab, even though she had done none of the work. We were all roped into taking care of her, but we were silent about it. Graduate students are investment protectors: the longer you’re in graduate school, the more investment you have to protect, and the more silent you become.

One day Frank said to me, “You’re good with rats.” I was flattered by his approval. Then he told me he was going to a conference for a week and asked if I would mind killing Lizzie’s rats while he was gone. “Some people are too sensitive to do this type of work, you know,” he said. I was astonished to learn that Elizabeth, who had been in the lab for eight years and had numerous research publications on rat physiology, had killed only one measly rat sometime in the distant past (and had immediately run from the room in tears). But I was an investment protector, and I realized that rat killing required less work than doing Elizabeth’s research for her, as some of my colleagues had to do. Killing rats for her was fast and physical and only as unethical as I cared to make it. And I picked my battles: mine was going to be when Frank slapped her name on one of my papers.

Then Frank took on a graduate student from Thailand named Ceci who was also too sensitive to kill her own rats. She said that killing was against her Buddhist religion. So Frank asked me to kill her rats for her. I figured I could fit them into my schedule.

Ceci came from a wealthy family in Bangkok and shared her affluence by generously bringing us food, like wonderful egg rolls with vegetables and crispy pieces of chicken and pork in them. But in a very short time, she became sharp-tongued, demanding, and irritable, and began treating me with contempt. Though I continued to kill her rats, I grew more and more resentful. Elizabeth was too sensitive. Ceci was not only too sensitive, but also too close to God to get her hands dirty. It was quite a burden on me, helping out these people so that they could continue to be sensitive in this harsh world.

As the months passed, I started grumbling about people not taking responsibility for their rats and — worse yet — being rewarded for it. My fellow graduate students got nervous and started avoiding me. They wanted to distance themselves from a potential explosion. They didn’t like it when I asked why Ceci couldn’t kill her own rats. “It’s against her religion,” they’d say, wolfing down her meaty egg rolls. Buddhism was a mystery to me, so I called the local Buddhist temple to ask about the killing of animals. I talked to a monk who listened to my question and finally said, “It’s like any other religion — people give lip service to it when it’s convenient. You know what I mean?”

The next day, while holding one of Ceci’s rats and letting it bleed into the tray, I asked her again.

“It’s against my religion,” she said nervously. She hated this topic.

“You eat meat,” I said.

“Killing rats is not the same thing,” she said, raising her voice.

“You eat meat,” I repeated. “It is the same thing.”

“It makes me feel guilty,” she said. I could see her pulse pounding in her temples.

“Does it make you feel guilty that I’ve been doing all your dirty work for over a year now?”

Her face turned red and she shrieked, “I am not as guilty as the person who does it! I am not guilty!”

I didn’t hear any more because I was barging into Frank’s office. I slammed my fists on his desk and screamed for ten minutes about degradation and manipulation and ethics and taking responsibility for your rats. I was careful to limit the focus of my tirade to Ceci.

When I finished he said, “Yeah, I understand. It’s like the guy standing at the urinal who asks the guy next to him to help him take a leak because he’s got the clap and doesn’t want to touch his own dick. It’s like that, isn’t it?”

I flopped down into the chair and looked at him. “It’s close enough,” I said.

We sat there without speaking for a few moments more, then I got up and walked out. I never killed another rat for anyone else again.

But I still had my own rats, and it got no easier. Rather than dedicating my dissertation to my husband or to a professor, I dedicated it “to all the white rats who took it in the shorts,” because they gave the most. The archivist at the library who signed the final approval for my Ph.D. said, “That’s the best dedication I’ve seen in a long time.” I had to agree.