By Sarah Zhang ’11
Photography by Noor Beckwith ’11
Harvard may not boast the reputation of “Animal House”, but just seventeen miles away from campus, the Concord Field Station could quite literally take the name. The research facility in Bedford is home to animals ranging from guinea fowls to frogs to African pygmy goats. A retired emu—the last from a former study on emu locomotion—still struts its stuff behind the field station’s main office.
Affiliated with Harvard’s Museum of Comparative Zoology (MCZ) and the Department of Organismic and Evolutionary Biology, the Concord Field Station accommodates the labs of Professors Andrew Biewener and Stacey Combes and serves as storage space for the MCZ’s oversized collections. The field station’s ample size—65 acres adjoining Harvard’s 650 acre Estabrook Woods—gives the scientists enough lab space to construct wind tunnels and outdoor insect habitats. Research at the field station focuses on the biomechanics of animal movement, which explains the presence of the rather exotic emu in Bedford, Massachusetts.
From Missile Silo to Zoological Lab
The facilities of the Concord Field Station originally belonged to a missile base built during the Cold War. When Harvard University acquired the land and surrounding woods in 1966, the field station was born. “Until recently there was a whole question of whether missiles were ever actually at this base,” says Biewener, the Lyman Professor of Biology and Director of the Concord Field Station, as he pulled up an aerial photograph to prove that there were indeed missiles here.
The base’s buildings have been repurposed for science: the barracks became the field station’s main building, housing offices, an animal surgery room, animal care facilities, and, closer to the building’s original purpose, a small apartment for visiting researchers. Reminders of the field station’s past are most apparent in the underground bunkers now used as storage. Inside the bunkers, equipment originally used to hoist missiles above ground is still visible amidst the dozens of whale, dolphin, and porpoise skeletons that make up the MCZ’s oversized cetacean collection. It is obvious why the whale skeletons, from whales that had beached themselves, have to be stored off-site: the jawbone of each whale easily surpasses the height of a grown man.
More interesting than the skeletons are the live animals that inhabit the field station. The late C. Richard Taylor, Biewener’s predecessor and founder of the Concord Field Station, was a pioneer in the field of animal locomotion. It was under his direction that the field station once housed kangaroos, wallabies, antelope, llamas, wolves, coyotes, ponies, and chimpanzees for the purpose of studying locomotion. The original treadmill from Taylor’s days in the 1970s—the first treadmill to have force plates embedded in it and the first to be used by a kangaroo—is still used in locomotion studies on larger animals, including goats and humans.
Lights, Camera, Flight
Today, Biewener’s research interests are primarily focused on smaller animals, particularly on avian flight. When he came to Harvard from the University of Chicago in 1999, a new wind tunnel, essentially an aerial treadmill, was constructed to study birds in flying. The birds, usually cockatiels, are released and photographed in the wind tunnel, which can generate winds up to 65 miles per hour.
Although the wind tunnels and treadmills have factored extensively into research at the field station, Biewener stresses the importance of studying animal movements in more natural environments. The repetitive walking motion on a treadmill, after all, is quite different from navigating a rocky, winding path, and the same is true of the constant speeds in a wind tunnel versus natural flight. One of the ongoing projects in Biewener’s lab studies the take-off and landing of birds, in which case wind tunnels are not very useful. Instead, doves are set up indoors to fly back and forth, and the displacement of air is tracked by laser imaging. In the same way that sunlight reveals dust in the air, laser lights up a thin sheet of air, and when a mist is sprayed, particles in the laser light can be tracked by a camera to calculate the flow field around the bird. Transducers, tiny devices that measure the flexion and extension of muscles, are also implanted in the birds to study how they use muscles in different maneuvers.
The same laser imaging set-up is used to study 90 degree and 180 degree turns in flight, the mechanism of which is still poorly understood. 180 degree turns are especially interesting because they involve the bird almost stopping in midair at the instant they are changing direction. Flying at slower speeds actually requires the bird to generate more force, which is why hovering is so difficult for most birds. Biewener hopes that laser imaging can shed some more light on the mechanisms behind these tricky turns.
However, avian flight is only one area of research in Biewener’s lab. Other active research projects include guinea fowl walking, frog swimming, and locomotion in goats.
“The immediate plan is to chase a goat around!” laughs doctoral student Carlos Moreno when asked about his work on African pygmy goats, another project supervised by Biewener. “It’s pretty nonscientific. You just holler and clap and make a lot of noise. And they run away down the corridor,” Moreno says about his goat-chasing techniques. The goal is to make the goat perform evasive maneuvers in order to study the biomechanics of turning and dodging movements. Chasing the goat is only the easy part, though probably the most physically strenuous.
Prior studies on goats at the field station have looked at bone bending in turns. Strain gauges are glued to the bone to detect bending, and the goat is shooed around an enclosed space. Results showed that of two bones in the leg, the radius has less variability in bending than the metacarpal. The radius is a curved bone, so bending mostly happens in one direction, in contrast to the straight metacarpal that can bend every which way.
The remnants of a “cinderblock mountain” once implanted with force plates, stand next to the goat’s runway as a reminder of past climbing studies. Current studies continue to focus on the biomechanics of 90-degree turns. A goat is chased down a plywood runway embedded with force plates that detect the force exerted by the goat on the ground. Additionally, a camera captures the movement of the goat’s joints, specially labeled with joint markers.
The act of chasing a goat down a plywood runway may sound silly in itself, but it simulates evolutionarily relevant behaviors by mimicking the act of a gazelle running from a cheetah. A tiny slippage can be the difference between life and death for the gazelle. In contrast to a treadmill, these more variable environments in which goats run allow for more insight into how animals turn and accelerate, as a gazelle running from a cheetah would.
Goats are chosen for the studies because they are representative quadrupeds, and also because they’re quite harmless. They don’t bite or kick, and are easily made to run. What about their horns? “Handles growing out of their heads,” says Moreno. Chasing goats also seems to be a favored activity of Duchess, a pet dog who sometimes makes in appearance at the field station. She stands in contrast to the dozens of other nameless animals that populate the field station, since usually, the scientists here are careful to keep a certain distance from their lab animals, labeling them by numbers instead of names. The animals are well cared for, especially by Pedro Ramirez, the animal care technician who has worked at the field station for [twenty] years – “He’s the reason that science can happen around here” says Moreno – but it’s inevitable that most animals will eventually reach their terminal surgery.
Technologies developed for these studies have also spilled into experiments on human movement and evolution. Professor Dan Lieberman, from the department of Human Evolutionary Biology, has adapted the goats’ force plates to analyze the dynamics of barefoot human running.
Bees Can’t Fly? Unraveling Insect Flight
Just outside the Station’s main lab space is a large tent-like structure with a running pond and a few plants. In early May, this greenhouse is rather empty, but as summer rolls around, the plan is to bring in local dragonflies to study how they chase prey. “Dragonflies do amazing aerial chases,” says Professor Stacey Combes, Assistant Professor of Organismic and Evolutionary Biology, who heads the second lab at the field station studying the biomechanics and behavioral ecology of insect flight.
Combes came to Harvard and the field station in 2008 from the Miller Institute at Berkeley, where she studied the flight of wild orchid bees in Panama. A wind tunnel, smaller than the one for birds, is also planned to be built for her study of insect flight. However, Combes too is interested in behaviors beyond smooth flight in a wind tunnel. “In all the years of studying flight nobody has ever looked at how turbulence affects flight,” says Combes highlighting her research interests. In Panama, Combes studied bees with a fan blowing out into the open air, which causes air to curl in and out creating turbulence. There she found that instead of retracting their large legs to reduce drag at high speeds, the bees actually stick out their legs to reduce rolling and pitching, much like a figure skater sticking out his arms to slow a spin.
Combes’ research builds on foundational work done in the past few decades. Until twenty years ago, the aerodynamics of insect flight was a mystery. Insect flight works differently from the more familiar aerodynamics of a bird or airplane, in which air flows faster over the top than the bottom of the wing to create lift, and the myth once circulated that “insects can’t fly.” The mystery was solved by studying robotic wings in mineral oil, which found that insects beat their wings so fast as to create a negative vortex around their wings, thus generating lift. Combes is interested in taking the study of insect flight outside of controlled lab spaces like a vat of mineral oil and marrying biomechanics with ecology, thus the dragonfly habitat outside. Turbulence, of course, is found in any natural environment, and an insect’s ability to fly in turbulence is likely to have evolutionary importance. Whether or not an insect can fly higher in the tree canopy, where there is turbulence, may affect its success at mating or evading capture.
Additionally, Combes studies the shape and material properties of insect wings, which bend and flop remarkably in flight, though the aerodynamic effects of this flexibility are unclear. Some of this work is done in collaboration with Professor Rob Wood’s Microrobotics Lab at the School for Engineering and Applied Sciences, which builds miniature robotic insects.
The use of robotics is a theme that runs through other research projects too. Until recently, Biewener’s lab group worked in collaboration with Boston Dynamics, the biorobotics company famous for Big Dog, an amazingly agile robot dog. Data from the goat studies as well as other dog studies at the Concord Field Station went into figuring out the mechanics of Big Dog’s movements.
Researchers at the Concord Field Station continue to undertake a wide range of studies on the biology and biomechanics of movement.The insights they obtain have applications in diverse fields, like robotics and human locomotion. Throughout its forty year history, the Station has harbored countless animals and scientists, and today it continues to be a center for novel research. Harvard’s ‘Animal House’ parties on.