Becoming a scientist
From the largest whales to the smallest germs, living things have evolved some remarkable ways to get around. Meet the physicist whose studies of locomotion are taking her places.By Caitlin Shure
Jasmine Nirody scoured her dorm room. She searched under tables and chairs, in corners and crevices, to no avail. Her snakes were officially missing.
“How did they get out?” she wondered. But in a sense, she knew the answer.
Then an undergraduate at New York University, Nirody had adopted the animals after using them in a senior thesis project to investigate how snakes move—in particular, how they maneuver across surfaces of varying textures. In the wild, the animals propel themselves off bumps and cracks in naturally uneven terrain, such as a forest floor. Nirody and her colleagues discovered that snakes have a fail-safe that allows them to wiggle on even the slickest of surfaces: their scales are ridged such that they can generate friction anywhere they go.
Of course, these findings weren’t particularly helpful to Nirody as she searched for her truant pets. All she knew was that they had the ability to slither almost anywhere—down the hallway of her dorm, onto the streets of Manhattan, and possibly into Washington Square Park to stun unsuspecting tourists.
She never recovered the three snakes.
Now a Rockefeller fellow in physics and biology, Nirody has moved on to study microscopic animals less prone to escape. Formally called tardigrades, the organisms also go by the name water bears—because when enlarged several orders of magnitude they really do look like adorable, if alien, bears.
Barely visible to the naked eye, tardigrades are the smallest organisms with legs, and therefore are the smallest organisms to walk. Nirody will show a video of their mesmerizing movement to anyone who swings by her office.
Her interest in the tiny perambulators? Same as her earlier interest in the snakes: She wants to know how they move. Not just the general gist of their ability to push their legs off the ground, but the minute details of the friction and inertia involved. She wants to understand the physics of it.
“When mammals walk, we’re very concerned about gravity,” Nirody says. “But these guys are more worried about the opposite problem—about floating away. So the question is: How do they adapt to these challenges?”
This line of research dovetails with others that Nirody is pursuing about how specific animals navigate their respective environments, or how a single organism might alter its behavior to accommodate a changing landscape.
Later, she says, this knowledge will help us build robots. Just as birds inspired us to build airplanes, so snakes, geckos, and even the tiny tardigrade, Nirody believes, may spur new innovations.
Nirody didn’t have pets as a child. The reasons were partly logistical: Her family moved around—from Mumbai to Florida, then to New Jersey—and transporting animals along with everything else seemed complicated. Moreover, she had somewhat nontraditional tastes in pets. She begged her parents for a turtle or a lizard, but the idea of a domesticated reptile terrified her mother. A cat or a dog might have been an easier sell, but Nirody wasn’t interested.
“I don’t really like mammals,” she states bluntly. “They’re just hairy.”
With her household at an animal impasse, Nirody directed her attention outside. She became enamored of bugs and keenly interested in how they move. In this respect, Nirody attributes to her younger self a fascination with mechanics. Like most kids, she wanted to know how things work.
Yet being a child, and lacking serious exposure to the world of basic science, she didn’t realize that her curious instincts were also a viable career. She assumed that becoming a medical doctor was the closest she could get. So after studying math—at the time of her snake experiment, she was a math major at NYU—she enrolled in medical school.
Once there, she spent her nights researching, coding, and taking on side projects that weren’t on the curriculum. At one point, it dawned on her that even though she was officially training to be a doctor, she was really becoming a researcher.
“I began to understand that there is a way to make a living answering the questions that interest me,” she says.
So she switched schools.
The ability to navigate diverse landscapes is key to an organism’s survival. If you can only amble on dry land, for example, you’ll be in trouble if you encounter a patch of mud.
Humans are capable of a transitioning between a few modes of mobility—from running on asphalt to trudging on sand to swimming in the ocean, for example. Still, there is a lot we can’t do locomotion-wise. We can’t scale trees in the manner of lizards. We can’t skate on the surface of water, like insects. And we’re really just mediocre swimmers.
So to acquire a more expansive understanding of the movement techniques that exist in nature, Nirody seeks distinctly nonhuman, nonmammal subjects—precisely the type of organisms that she’s always been drawn to.
After experiencing the rigidity of medical school, Nirody knew she wanted to pursue a career path that would allow her to follow her evolving interests and to ask a broad range of questions. She enrolled in a graduate program in biophysics at the University of California, Berkeley.
There, she met the mathematical biologist George Oster, who served as both her adviser and as a model for the kind of scientist she wanted to become.
“He found ways to make himself useful in a lot of different areas,” she says. “Because if you have a physics background, you can pop your head into a biological or engineering field and take a look at the math, and then just pop your head back out again.”
“If you polled all the organisms on earth, flagellated swimming would be by far the favorite means of locomotion. So I figured I should go with the majority vote.”
Over the course of her graduate studies, Nirody popped in and out of an impressive diversity of fields. Rotating through labs, she first studied color patterns in seashells, then the mathematics of genetic ancestry, then cockroach locomotion.
Cockroaches weren’t for her—“I do have my limits in terms of what animals I can spend time around,” she says—so she ended up working on bacteria. Specifically, she investigated a mode of bacterial movement known as flagellated swimming. A flagellum is a wispy appendage that extends from a bacterium’s body, whipping back and forth to propel the microbe through water or other fluids. This techinque is incredibly efficient, and is a dominant mode of movement in nature.
“If you polled all the organisms on earth, flagellated swimming would be by far the favorite means of locomotion,” says Nirody. “So I figured if I was interested in locomotion, I should go with the majority vote.”
She devoted most of her Ph.D. work to understanding the motor that drives flagella to spin around. This system, she learned, functions somewhat like a wheel and axle. At the microscopic scale of bacteria, however, wheels lack sufficient mass to accumulate momentum and need constant nudging to stay in motion. So rather than spin continuously, the microbial motor rotates in incremental steps.
Resolving the mechanics of this little system answered the type of fundamental how-does-it-work question that had always compelled Nirody. And, as a bonus, it gave her the satisfaction of knowing her work might one day translate into useful medical applications. Flagellated bacteria include many of the infectious microbes that pose a threat to human health, including E. coli, Salmonella, and the bacterium that causes cholera. And understanding how these microbes get around could inspire new approaches to fighting them.
“How do you make something not infectious anymore?” asks Nirody. “Take away its ability to move.”
She also views her work on microscopic motors as potentially useful for the development of tiny robots, or nanobots. If you want to design nanobots, it makes sense to draw inspiration from systems that nature has used again and again and again, says Nirody. Evolution is a brilliant engineer, and she doesn’t secure patents.
Complementing Nirody’s infectious obsession with hairless organisms is a similarly infectious futuristic imagination. The field of robotics has made extraordinary technological strides in recent years, but when it comes to literal strides, she says, robots are currently quite primitive.
“Robots only learned to convincingly walk about a year ago, and they’re pretty limited in terms of where they can go. But these guys,” she fawns, pointing at a water bear on her computer screen, “these guys walk in all sorts of environments.”
As she verbally pivots from microanimals to nanobots and back again, it’s difficult to decipher where Nirody’s professional interests end and her personal obsessions begin. And that, according to Nirody, is exactly how it should be. She pursued mechanics because it granted her the freedom to enjoy a curiosity-driven career; and she accepted the fellowship at Rockefeller for the same reason.
A standard postdoctoral position requires committing to a lab and a research program. It entails burying one’s head in a very specific project for four years or more; and, for biologists, it usually entails commitment to a single model organism. While this kind of program works well for a lot of scientists, to Nirody it sounded terrible.
As a fellow in physics and biology, she has access to the university’s resources and researchers, but she works largely on her own and has the freedom to pursue multiple projects and as many organisms as she wants. She has access to mentors and advisers when she needs them, but nobody is looking over her shoulder or telling her what to do. Within less than three years, she’s been able to continue her research on flagellated swimming, launch an investigation into water bears, and finish up a study exploring how geckos traipse across the surface of water.
Concurrent with her position at Rockefeller, Nirody also landed a fellowship at Oxford University’s physics department. So she is now bouncing between continents and research subjects; and, true to form, she ably transitions across these landscapes.
“I imagine I’ll answer a lot of different kinds of questions in my career in science,” she says. One question she’ll never get to the bottom of: Where did those snakes go?