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Fossil discovered by University of Chicago professor bridges gap between fish and humans

by Marlena Chertock, March 8, 2010

Professor at Chicago University, Neil Shubin, researched the link between humans and fish and presented his findings at Elon University. Photo by Marlena Chertock.

A fish paleontologist and author of “Your Inner Fish: A Journey Into the 3.5 Billion-Year History of the Human Body” recounted the seven years he spent digging for fossils March 8 at Elon University.

Neil Shubin searched for the connection between humans and fish.

“You spend your day looking on the ground for bones weathering out of the surface, for bones that sparkle in the light,” Neil Shubin said. “Your eye gets really good at seeing them.”

Shubin, a professor at University of Chicago, described the interconnection between fish and humans, saying that most of human history can be told by understanding fossils, genes and embryos of other creatures. According to Shubin, fossils and DNA explain human evolution.

“In every cell, organ and gene, we carry an entire 3.5-billion-year branch of history inside of us,” Shubin said.

Shubin spent seven years searching for fossils among Devonian rocks in Arctic Canadian islands. The rocks were the perfect age for the fossils he was looking for: 375-380 million years old.

In Melville Island, Canada, Shubin found a flat-faced fish with a head that moves independently of the neck and shoulders. He said the creature had characteristics of both land-living animals and fish. This creature was the “bridge between” fish and early land-living creatures.

“(The island) is incredibly remote,” Shubin said. “It’s daylight 24 hours a day.  We have to bring our own food. It’s 100 miles from the nearest base, and apparently there are polar bears. And polar bears eat people. Being eaten by a polar pear wasn’t the fate I had in mind.”

But Shubin and other researchers took the risk after Shubin found a 1998 college textbook that portrayed a map detailing an unexplored territory in Canada containing Devonian rocks, where he said he thought he would find the link between fish and land-living animals.

“We were debating whether to go out into the field in 2004,” he said. “I looked at (what a researcher had found on the fourth day) and I knew that our seven years of effort was now successful. What I saw was a flat-headed fish and it was sticking out of the rock.”

Photo by Marlena Chertock.

Shubin stressed the importance of finding out how creatures evolved from being water-bound to land-walking. The flat-headed fish his group found is an explanation of this evolution.

As the founder of the fossil, Shubin had the privilege of naming it. He said he wanted the link to have an Inuit name since it was found in Inuit territory.

“We met with the Council of Elders,” Shubin said. “We wanted a name that’s meaningful to them and to us. But a third criteria was a name we could pronounce. They have no word for fossil (but) Tiktaalik means large, freshwater fish.”

So Tiktaalik was the name, and it helped connect the development of humans and fish. Shubin said fish are simpler versions of the human body. According to Shubin, the bones are shaped differently but the patterns are similar.

“Knowing something about fish anatomy changes the way you look at the world,” he said. “(It changes the way) you look at the human body.”

The features found in Tiktaalik are part of “our own anatomy,” Shubin said. Through time the gills became human necks, webbed limbs became wrists, he said.

Shubin said the muscles and bones he used to give the speech and the muscles and bones the audience used to listen correspond to gills in these ancient land-living creatures.

“We share so much with the rest of life on our planet and it’s seen when we look at fossils, when we look at embryos,” he said. “There’s a tree of life that goes from fish to reptiles to humans.”