immune systems are identical, there will be no rejection. If you test a particular drug or treatment on mice of one inbred strain, any variability that you see as a consequence can’t be blamed on genes. Something else has to be the cause. Having this kind of genetically level playing field has been extremely useful for researchers. Some of the strains of mice that Little developed are still being used by researchers today.
In 1922, at the astonishingly young age of thirty-three, Little became president of the University of Maine and three years later got the same gig at the University of Michigan. At Michigan, Little demonstrated quite an ability to irritate people. He annoyed the university regents and the governor with his outspoken views on birth control (he was for it), euthanasia (he was for it), and eugenics (he was for that, too). His tenure as university president lasted only a few years.
If he got under the skin of his higher-ups, he nevertheless managed to befriend some of nearby Detroit’s wealthy industrialists. When Little left Michigan, he even convinced Edsel Ford and Roscoe B. Jackson, the president of the Hudson Motorcar Company, to bankroll the new institute he wanted to build to study mouse genetics.
Today, the lab employs some twelve hundred scientists, technicians, and administrative staff, most of whom are involved in some way or another with probing the mouse genome. The lab scientists don’t work with all eight hundred thousand rodent residents. Many of the mice are supplied to researchers at other institutions.
There’s a surprising amount of security at the lab, especially for the building where most of the mice are housed. It’s not so much that scientists are worried about theft or escape. A bigger worry is that animal rights activists will try to break in and wreak havoc. Lab officials insist that the main reason for the security is to protect the mice from humans who may be carrying diseases that could be harmful to the rodents. Once a year, however, the lab does let humans view the mice, and that’s during what’s called the Mouse Clinic.
The clinic is part of the two-week summer course on mammalian genetics that the lab has conducted for the last half-century. Senior genetics researchers from around the world agree to teach at the course, partly because the Jackson Lab is a good place to hobnob with colleagues in mammalian genetics, and partly because Bar Harbor can be spectacularly beautiful in the summer. (It can also be rainy and foggy for days on end, causing you to curse the vacation brochure that convinced you to spend your entire two-week holiday there.)
Graduate students and recently minted Ph.D.’s attend the course, and the Mouse Clinic is one of the highlights. In it, the lab brings out examples of its most interesting mouse strains, and scientists at the lab explain their research to the course participants. The clinic takes place in a parking lot next to one of the lab buildings under a large tent, a hundred feet long and forty feet across. There are about two dozen tables under the tent, and on every table are several clear plastic boxes, each a bit larger than a shoe box and containing a different strain of mouse. You can easily see the mice inside the boxes. Some are brown, others are white. One mouse even has a green glow if you shine ultraviolet light on it.
In some boxes there is only one mouse; others hold several. All of these mice at the clinic have one thing in common: “They’re not very happy,” says Peggy Danneman. Danneman is a senior veterinarian specializing in lab animal medicine. She says there are several reasons for these mice to be pissed off. First of all, mice detest open spaces. Yes, there’s a tent, but the tent has no walls, and for a mouse, this is about the same as being plopped down in the middle of the great outdoors.
“Mice want to be close to a wall or sheltered,” says Danneman. Even though there’s no threat to these mice in their protective plastic cages, historically, a mouse out in the open is a mouse in trouble. That’s because just about every larger carnivore wouldn’t mind munching on a tasty mouse snack. “You see the same thing with bright lights,” says Danneman. “Mice do not like bright lights, and I would postulate it’s for the same reason.” Bright lights would make them easier to spot. Although there’s no direct sunlight inside the tent, it’s plenty bright. While these things may be temporary and unpredictable, for a mouse, they could cross from unpleasant into genuinely dangerous (as far as they can tell). Yet that’s just the beginning of the assault on mouse sensibilities that the Mouse Clinic represents.
Mice hate being put in a freshly cleaned box, and these boxes are spotless. “Humans change the cage because it starts to smell, and they don’t like it,” says Eva Eicher, one of the lab’s star geneticists. “But the mouse would probably prefer to have the cage a little dirtier and changed a lot less often.”
Eicher says there are other reasons that mice don’t like to have their boxes changed. “Pretend I’m a mouse, living in my house,” she says. “I’ve just gotten the house set up. I’ve got my bedroom and my bed all made. I’ve got my bathroom all set up.” Mice urinate in the same place. They defecate anywhere, so the analogy’s not perfect, but you get the idea. In any case, the clean new cage might be aesthetically pleasing to humans, but to mice it means that every few days they have to rebuild their world. How much fun is that?
Then there’s how the move to a new abode occurs. “All of a sudden, some giant thing grabs you,” says Eicher. “And they grab you by the tail so your butt’s up in the air and your head is down.” What’s more, it tends to happen during the day, and mice are nocturnal. They sleep during the day.
Moving can also mean social disruption. “Maybe I’m with five or six males,” says Eicher. “And one of the males is a bully. He has made everybody else kowtow to him. But when we get moved into a new house, the bully has to reestablish himself, so he runs around biting everybody.” The rebuilding, the sleep disruption, the social anxiety—none of it is life threatening, it is simply disruptive and not at all how the mouse expected things to go.
In Italian, in response to a question like
This isn’t only an Italian thing (or a mouse thing). People generally like it when things are in place. Our natural tendency is to organize—from the cans in our cabinets to the files on our desktops to our careers and families. It’s frustrating when things are out of order.
This trait isn’t confined only to living things. Materials like to have things in place, too—particularly when it comes to the atoms that compose them. Yet sometimes a material is faced with competing forces that make it difficult to know how to arrange things. Frustration (in physics, too!) is a deep internal conflict with no clear resolution.
Physicist Leon Balents is a frustration expert, although he doesn’t know exactly where the term came from. “I’m not sure whether it’s that the theoretician is frustrated in not being able to figure out how the system should resolve these competing forces. Or whether the material is frustrated in not knowing how to resolve the competing forces.” It seems to work on two levels.
Glass and plastics are often frustrated, but “the classic thing to talk about in the case of frustration is a magnet,” says Balents, who works at the University of California, Santa Barbara. A frustrated magnet isn’t really what people think of as a magnet at all. Frustrated magnets won’t even stick to anything.
Take that sombrero magnet that your friend brought back from Mexico that you’ve hidden under a menu on the fridge door. The sombrero, technically a “ferromagnet,” sticks to the fridge because of its electrons and the way they spin inside the atoms that make up the magnet. In ferromagnets, all of the electron spins want to orient in the same direction, just as the magnet in a compass wants to point north. “In ferromagnets, each spin wants to line up with its neighbor,” says Balents. “You can think of it as a force, where each one tries to force the other one to line up.” The cumulative alignment of these electron spins gives the magnet its ability to attract things.
In these magnets, figuring out how to put things in place is straightforward—at least, at certain temperatures. “There’s always a simple way to minimize the energy of all pairs of spins,” Balents says. “Just point them all along the same axis.” Every electron spin goes in the same direction as the one next to it.
Ferromagnets are much less common than antiferromagnets, Balents says. And antiferromagnets want a different arrangement. Their tendency is to order their electron spins in opposite directions. (This is why antiferromagnets don’t repel or attract anything—there’s not a cumulative force in one direction.) And this is where things can get frustrating.
If the atoms are aligned in a row—think of a battleship pegboard—it’s easy to alternate the spins: one up, one down, one up, one down. If the atoms are arranged in a triangle, however, there’s not a clear solution. If the spin on top of the triangle goes up, and the spin on the right corner goes down, what does the left side do? “The
