Thursday, February 12, 2009
Researchers at The University of Texas at Austin, in collaboration with the Ethiopian government, have completed the first high-resolution CT scan of the world’s most famous fossil, Lucy, an ancient human ancestor who lived 3.2 million years ago.
John Kappelman, professor of anthropology in the College of Liberal Arts, led the scientific team that conducted the scan of Lucy, whose remains include about 40 percent of her skeleton, making her the oldest and most complete skeleton of any adult, erect-walking fossil of a human ancestor.
Richard Ketcham, an associate professor of geology in the Jackson School of Geosciences, manages the CT laboratory and handled most of the scans.
Here are some of their thoughts and reactions.
Save the last scan
For Richard Ketcham, a highlight of the labor of Lucy came on the 10th day, when it was all supposed to have been over.
Scans had been made of all 80 pieces of Lucy’s skeleton in The University of Texas at Austin’s High Resolution X-ray CT Facility.
The team had even had its post-project toast the night before at Sao Paulo’s, a Brazilian restaurant on the north edge of campus, and had exhaled a sigh of relief.
“We were glad to see her come and glad to see her go,” Kappelman said.
But it was found that one of the bones had not been scanned. It was “a little toe flange,” Ketcham said.
So it was back in the laboratory the next morning, a Saturday, for the last scan.
The highlight for Ketcham is that he brought his daughter, Genevieve, 11 years old, and Tristan, who was nine at the time of the scan and is now 10.
“They were eager to see it, but disappointed they didn’t get to touch it,” he said.
Then Ketcham and Lucy headed out of town, within hours of each other, to different destinations. He went to a conference in Anchorage, Alaska, and she went to Seattle for her next exhibition.
An exciting first
Kappelman had studied Lucy since he was an undergraduate student, but hadn’t seen her up close, personal and laid out at life size until he went to her exhibit at the Houston Museum of Natural History–”the way a quarter of a million other people saw her.”
When she arrived for the CT scans in Austin, it was the first time he’d seen Lucy outside a display case.
“That part of it was very exciting because she’s really one of the centerpieces of human evolution,” he said. “There’s no question about that.”
Protocol for a national treasure
The operation to scan Lucy in the university’s CT machine was as top secret as they come and the UT participants didn’t question any of it.
“Whatever it takes for a project like this,” Ketcham said. “It being a national treasure, the only national treasure we’ve ever scanned, an extra layer of care in all respects is understandable.”
Alemu Admassu, a curator with the National Museum in Addis Ababa, was the only person who could touch Lucy’s bones. Ron Harvey, a conservator from Maine, assisted in the process.
Ketcham said Admassu and Harvey followed a set protocol in preparing a specimen for scanning.
“He (Admassu) and the conservator would take it out and compare it to the photograph of the specimen,” he said. “Then they would weigh it, record the weight of the specimen, which is always a few micrograms off because it absorbs humidity. Then they shined an ultraviolet light on it.”
They repeated each step when the specimen went from the scanner to the case.
Learning from Lucy
Even though she’s 3.2 million years old and has been exhaustively studied since her discovery in 1972, Lucy isn’t done telling us about herself and her world, Kappelman said.
“There’s still new information to gain and some of that information is asking new kinds of questions built on what we’ve learned over the last 30 years,” he said.
Many of those questions might be asked and answered by some of the thousands of children who see Lucy on exhibit and who will be able to examine her bones online, he said.
“In thinking about the hundreds of thousands of kids who’ve gone through that exhibit,” he said, “the chances are quite good that some of those kids are going to be the ones doing the groundbreaking studies in another 10 or 20 or 30 years, and having the opportunity to see this fossil may have ignited the spark that puts them on this kind of career. It’s just a remarkable opportunity for us, for one, but also for the public to see this fossil and it’s very generous for the Ethiopian government to share this national treasure with us.”
The images from the CT scans will provide scientists the means to see things about Lucy that were not possible before.
Kappelman said they can look at detail of how certain bones are constructed and where force was transmitted.
Looking at an arm bone, that could help them determine how much Lucy climbed. Or, looking at her well-preserved mandible, tell what she ate.
Lucy the Longhorn?
While it’s probably not good to project too much humanity into Lucy, it is nice to think that maybe she enjoyed her time at UT.
That, maybe, as she was leaving town, Lucy was wearing a Longhorns football jersey, the number 3.2 million on the back, and mustering as many hand and finger bones as she could, she flashed a “Hook ‘Em” sign as the Tower receded into her past.