The unsung heroes of scientific research are the graduate students*. Graduate students provide the enthusiasm to run experiments 7 days a week and all hours of the day and night to generate data for publications and their own thesis projects. The fresh perspective a graduate student brings to an area of research can also provide new ideas to their mentors and collaborators, spotting connections or opportunities that might have been missed by those with more experience. In even the biggest discoveries, graduate students play a critical role.
That was the take-home message from Neil Shubin’s keynote lecture at last week’s Scientific Diversity: People, Research, Careers Symposium organized by the Biological Sciences Division. Following talks by graduate students, post-docs, and young professors, Shubin delivered a characteristically fascinating and funny tale about his laboratory’s discovery in 2004 of Tiktaalik, an important transitional fossil between sea and land animals. The story of Tiktaalik may have been familiar if you’ve read Shubin’s excellent Your Inner Fish or seen him speak before. But this time around, Shubin put added emphasis on the critical role of his graduate students and collaborators, both in setting the stage for the fossil’s excavation and in the continued quest to learn from Tiktaalik’s remains.
In fact, Shubin said the very spark for Tiktaalik’s discovery came from a friendly argument between him and his former graduate student at the University of Pennsylvania, Ted Daeschler. Shubin and Daeschler had found many Devonian era fossils of fish with primitive limb-like structures in their home state, but wanted to find even earlier examples of the transition from fins to limbs. So they had to pick the right place for an expedition, with exposed rocks of the right age for finding such an elusive fossil.
“Everything changed for us in a conversation in my office in 1998. We were having an argument, as graduate students and their advisors typically do, and we settled the debate with a college geology textbook,” Shubin said. “I was thumbing through the book, and I hit a diagram that changed the course of my career.”
The diagram showed the three areas where the ancient deltas Shubin was seeking were known to be exposed. Two of them had already been the site of expeditions, but the third – a cluster of islands in the Canadian arctic – was largely unexplored. Shubin and Daeschler “ran to the library,” he said, and found a paper that confirmed the region held the exact type of rock they were looking for.
“It was truly exciting; here was a whole part of the world that was unexplored,” Shubin said. “After we saw this, we went to Chinese food for lunch, and my fortune cookie said, ‘Soon you will be at the top of the world.’”
It took six more years for an expedition to find Tiktaalik, embedded in the rocks of Ellesmere Island. It took a further two years for the fossil to be prepared sufficiently (by preparator Robert Masek) for analysis and publication. The rest is history – massive media coverage, a book, and even The Colbert Report. But the story of Tiktaalik isn’t over, and it is graduate students that are writing the newest chapters.
“It’s really a nice system, because so many bones are so well preserved, for us to ask new kinds of questions, and this is where graduate students come in,” Shubin said.
One of the mysteries about Tiktaalik is a simple matter of biomechanics: how does he open his mouth? With a broad, flat head and not a lot of room where jaw muscles would have attached, it doesn’t make intuitive sense how the creature could have opened its mouth when underwater. So graduate student Justin Lemberg, working with professor of organismal biology and anatomy Michael LaBarbera, built a model of Tiktaalik, put it into a water flow tank, and watched what happened.
“The shape of the head in the water can actually bring about passive jaw opening,” Shubin said. “Justin and Michael looked at this in an entirely different way.”
Another question about Tiktaalik is how it might have taken those important early steps on land. The fossil and artist’s reconstruction shows “legs” that are still very fin-like: small, thin, and seemingly not that well suited for supporting the animal’s weight. To figure out how Tiktaalik might have looked in motion, Heather King, graduate student in Department of Organismal Biology and Anatomy, turned to its closest living relative – the lungfish. When moving quickly, the lungfish propels itself with its tail, like most fish. But when it moves slowly, a surprise was revealed.
“I looked at this fish for my entire career,” Shubin said. “But Heather looked at this fish in a completely different way. She put the creature in a flow tank, and watched it move…at slow locomotion, this thing is a walking bratwurst.”
Those projects have blended elegantly into the primary mission of Shubin’s laboratory, to understand the formation of limbs and organs in both the fossil record of evolution on Earth and the embryonic development of individual species. Other graduate students have worked on the embryonic side of the lab, such as former student J. Andrew Gillis’ project on the genes that control appendage growth in sharks and elephant fish. At each level of Shubin’s laboratory, graduate students are driving the research in new and unexpected directions. Hence the alternate title of Shubin’s talk: “How Graduate Students Can Change Everything.”
“I’m an old person and I look at the world in a set way,” Shubin said. “Oftentimes it takes a graduate student, new and raw, to look at a problem in a whole new way, and often that sets us off in an entirely new direction.”
* – full disclosure: I used to be one.