* All italicized passages are selected from Casey Dunn’s scientific publications.
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Casey Dunn is as much an adventurer as a scientist. His work brings him to remote corners of the world, where he gets to study some of the planet’s most esoteric and unsung creatures. In doing so, he hopes to better understand how life on Earth came to be so diverse.
Ever since Ernst Haeckel published his artistically illustrated phylogenetic trees, scientists have worked towards understanding the evolution of multicellular animals and the relationships between their main lineages.*
By all accounts, Dunn came out of the womb in a lab coat. Born in Reno, Nevada to an engineer father and an elementary school teacher mother, he cannot remember a time when science was not a driving force in his life.
Dunn’s father was a mining engineer and then an electrical engineer. Both jobs required moving often, and by the time Dunn went to college, they had moved at least 25 times.
Living in places like California, Oregon and Nevada, “I got to see a lot of amazing country in the West,” Dunn recalls. Spending time in mining camps sparked Dunn’s interest in geology, and from an early age he associated science with his love for being outdoors.
For Dunn, science has never been bound by discipline. When he wasn’t outdoors, he was figuring out how to build rockets. As he grew up, he became interested in chemistry and started doing more technical, hands-on science.
His chemical exploits drew him to molecular biology, which he approached with a fearless, autodidactic fervor. By high school, Dunn had set up a functioning molecular biology lab in his home’s kitchen. “It’s kind of surprising how much molecular biology you can do off the shelf,” he said.
Molecular biology, which enables the examination of organisms at the level of genes and gene products, provides the opportunity to collect many more character data relevant to discerning among competing phylogenetic hypotheses.
Dunn’s family alternately cultivated and tolerated his homegrown science. He would copy segments of DNA through a procedure called PCR by sitting three pots at different temperatures on the stove in place of the elaborate PCR machine used in labs. His younger sister, a willing research assistant, would sit at the stove for hours helping him move his samples from pot to pot. It became commonplace to open the refrigerator and find stacked plates of E. Coli.
Dunn’s interests, however, soon expanded beyond his home kitchen. He started working in a lab at the University of Oregon, where he gained valuable lab skills. While working there, he met some biologists doing work in the tropics. They convinced Dunn, who had already decided he wanted to take a gap year before college, to head to the tropics as well.
For a year, he was a guide in the Amazon and did butterfly surveys in Ecuador. For Dunn, the experience was a welcome return to the outdoors. “By then,” he said, “I knew I was interested in biology.”
Upon his return, he headed to Stanford for college. Having tinkered with electronics and engineering through high school, he took advantage of being in Silicon Valley with his characteristic knack for seamlessly traversing academic fencelines. Demonstrating the same enterprising spirit with which he approached molecular biology and field biology, Dunn worked in Silicon Valley throughout college, gaining computational experience and making some money for school along the way.
Computerized phylogenetic analysis allowed the researcher to handle much larger morphological datasets and analyze the information in a more objective and thorough manner. Hence, within a relatively short period, the computer and phylogenetic software became standard tools for systematists and prompted the publication of numerous morphology-based hypotheses on animal evolution.
Dunn seemed to approach this period of his life with a singular determination to have as many experiences as possible. In addition to working in Silicon Valley, he spent time doing bird surveys in Indonesia, writing a software for looking at butterfly population dynamics, working in a lab that built satellites and writing up a thesis on his butterfly work from Ecuador.
In an introductory biology class, Dunn met Erika Edwards, who would eventually become his travel companion, professional counterpart and life partner. Though they were instantly drawn to one another, they did not start dating right away, in part because Dunn was planning to take a semester off to cross the Pacific Ocean in a pedal boat.
We appraise the merits and limitations of several alternative molecular phylogenetic approaches that are currently used to address the vexing question of metazoan interrelationships.
At the time, he had met Jason Lewis and Stevie Smith, two men who were on a mission to circumnavigate the globe on solely human power — bicycling and skating across land, and pedal boating and kayaking across water. They recruited Dunn and his friend John Walker to make the 2,400-mile trip from the American West Coast to Hawaii. They departed from Monterey, California in Lewis and Smith’s 26-foot long pedal boat named Moksha, Sanskrit for liberation.
Alone at sea in a tiny boat, Dunn described, “The ocean’s color has changed from green to deep blue, and the last of land has long since slipped beneath the horizon. We have passed through several schools of jellyfish, and pedaled the night away listening to whales as they surfaced to breathe. We never caught a glimpse of the mammoths, but were very much aware of their presence.”
Most siphonophores are active swimmers that spend their entire lives in the deep-sea. They are typically elongate and rope-like, with some reaching lengths of 40 meters or more, making them the longest animals in the world — even longer than a Blue Whale.
Unfortunately that year, 1997, was an El Niño year — one of the strongest ever. Dunn and Walker made it 140 miles off the coast of Monterey before running into a wall of storms. With their lives in peril, they had no choice but to turn back.
Eventually, the pair had to be rescued and towed their last 20 miles to land by the Coast Guard. In total their journey lasted ten days. In the ensuing storm, Moksha capsized and sank, and the expedition team had to return later with kayaks and scuba gear to retrieve the sunken beast.
Fifteen years later, Dunn still struggles with how to convey the lasting impact the experience had on him. “There are a lot of ways to explain it,” he reflected. After minutes of stuttering and groping for words, he settled on describing how the event reordered his priorities.
“There’s a clarity that comes with situations where the outcomes have such big implications – like whether you’re going to drown or not. We might worry as much about a lot of things in our daily lives, but in the end, the implications aren’t actually that big. To experience something that really is life or death helps put a lot of other things into perspective.”
This experience perhaps gave Dunn a sense of urgency towards embracing life, or at the very least, helped him maintain a sense of balance in what would become an incredibly prolific early career.
He went back to school, this time pursuing a romance with Erika. Despite taking time off, Dunn finished in less than three years, loading up on courses during his other semesters.
After college, he and Edwards moved to Fairbanks, Alaska, where they lived in a cabin and worked odd jobs. Dunn scooped ice cream, waited tables and worked as a projectionist showing movies in a bar, while Edwards worked as a barista.
Though it was supposed to be their time off from science, Dunn and Edwards could not stay away from it for long, and both of them ended up working in labs. As a lab technician, Dunn drove snow machines around the countryside in the winter servicing science machines and equipment.
Dunn jests, in defense, that getting science jobs was partly pragmatic. “We lived in a cabin that didn’t have showers, which isn’t that rare in Fairbanks,” he said. Working in a university, he and Edwards had access to showers that were nicer than the ones at the laundromat, where many other people resorted to bathing. The thought process went something like, “I guess we have to do science if we want to shower in the winter,” he explained with a laugh.
The specimens were rinsed 3 times (10 min each) with ice cold buffer containing 500 mM sodium chloride and 50 mM sodium cacodylate.
After a year, Dunn and Edwards both headed to Yale for graduate school. It was there that Dunn discovered his favorite animal, and what would become one of his most prominent study subjects: siphonophores. They appear to be single jellyfish, but are actually colonies of specialized individuals — the most famous example being the Portuguese Man o’ War.
“Siphonophores have lots of bodies,” said Dunn, “and those bodies are all genetically identical, and they’re attached to each other. All of those bodies do completely different things — some just feed, some just reproduce and some move the whole colony around.”
Dunn studied the body form of siphonophores, hoping to piece together how they evolved their colonial structure. By looking at siphonophores’ evolutionary history, Dunn hoped to begin answering questions like how complex multicellular organisms such as humans evolved from single-celled organisms.
Siphonophores are free-swimming colonial hydrozoans (Cnidaria) composed of asexually produced multicellular zooids. These zooids, which are homologous to solitary animals, are functionally specialized and arranged in complex species-specific patterns. The coloniality of siphonophores provides an opportunity to study the major transitions in evolution that give rise to new levels of biological organization, but siphonophores are poorly known because they are fragile and live in the open ocean.
Following graduate school, Dunn and Edwards went to Hawaii for postdoctoral work. There, Dunn started to grow curious about evolutionary trees and how to go about filling in their missing branches. He began to apply the computational skills he had learned in Silicon Valley to figuring out the relationships between animals — work that he still carries on today.
After two years in Hawaii, Edwards got a faculty position at Brown’s Ecology and Evolutionary Biology department. A year after their arrival, Dunn also got a tenure track position in the same department. At Brown, he has continued to weave together his many threads of interest. He wants to continue constructing “genealogies” for all the organisms on the planet and determine how biodiversity has unfolded over the history of the Earth.
A clear picture of animal relationships is a prerequisite to understanding how the morphological and ecological diversity of animals evolved over time.
Dunn’s toolbox is large, and he’s constantly adding new pieces to it. His research relies on a combination of fieldwork, labwork and computation work. A given project might involve going on boats and collecting organisms with robots that can probe thousands of meters into the ocean, using traditional lab techniques like genome sequencing or microscope work and creating new computer programs to make sense of massive data sets. It’s a challenge of adaptation, and Dunn loves it.
So many questions are wide open — some requiring the same tools and approaches as the naturalists of the Age of Exploration, others necessitating modern high-throughput sequencing technologies … Rarely do biologists have such an excellent opportunity to pull together such disparate tools in the pursuit of core conceptual questions.
With his omnivorous curiosity, Dunn constantly finds himself wanting to do too many things. Now that he has the freedom and resources to dictate his own research, he has to restrain himself from taking on too much.
Being a professor is like “being at an amazing feast, with all this gorgeous food, and someone hands you a Dixie cup,” he said. Though it’s a painful limitation, “what you do get is wonderful.”
Beyond research, Dunn wants to share his awe towards the diversity of life with his students. Anyone who takes his invertebrate zoology class is first won over by his boyish grin and cozy beard, then by his infectious enthusiasm for the whole animal kingdom.
Dunn’s audience, however, is not just limited to his students and colleagues. In 2009, he created CreatureCast, a collaborative blog that showcases original podcasts, often made by Brown and RISD students, about biology. Inspired by podcasts like This American Life, Dunn wanted to use narrative storytelling to share compelling, digestible science lessons. Most of the episodes take the form of short videos, but Dunn encourages multimedia experimentation.
Since its inception, CreatureCast has expanded and gained considerable recognition. Many news outlets pick up CreatureCast videos, and episodes are re-posted on Scitable, a website run by the prestigious science publication Nature. By now some videos have received over tens of thousands of views. Dunn is excited about the changing landscape of science communication, particularly the increasing accessibility of science to audiences of all ages and backgrounds.
Coming from a childhood where he could never commit to just one discipline, Dunn is also determined to convey to students that they are not limited by binaries. For instance, “a lot of students have this tension about whether you can do art and science,” said Dunn. “That’s not a mutually exclusive decision — you can do both those things.”
Nearly all metazoans show signs of bilaterality, yet it is believed the bilaterians arose from radially symmetric forms hundreds of years ago.
He wants to extend that open-mindedness to the entire field of academic science. “Science is so tracked and hierarchical,” he said. “A lot of people in science think of themselves as people who don’t like tracks and hierarchy, but yet we’ve constructed one of the most hierarchical systems.”
Speaking from his own experiences, Dunn tries to emphasize to his students the value of taking time off. He believes that it’s important for students to have a broad range of experiences before committing to the confined track of academia.
Meanwhile, his biggest mentees are his and Edwards’s two children — a two-year-old son and six-year-old daughter. Dunn’s preferred way to spend free time is to go out and explore with his kids. “I just took them to the Ladd Observatory on Tuesday — oh, I love the Ladd,” he said with a giddiness that betrays his typical professorial composure.
Dunn seems to relish the excuse to relive the childhood magic that comes with discovering new things about the world — or perhaps he never lost it.
“The reason I do science is because I find so much of it so beautiful,” he said. “We tend to sterilize our presentation of science. The motivation for it can be just how beautiful something is: Look at this amazing idea. Look at this amazing organism.”
There is no doubt that metazoan systematists will continue refining the position of many of the branches and twigs in this entangled tree of animal life, but we are getting to a point where the main branches are becoming well understood, the prerequisite to exploring other evolutionary questions in animal biology.
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This piece was originally written for a Brown University course, “Introduction to Creative Nonfiction” by Kate Schapira.