Preserve old bones with modern technology

A team of anthropologists from the University of Colorado at Boulder aims to change the way scientists study old bones without damage.

If this sounds like a macabre goal, consider this: Well-preserved pieces of bone are valuable to researchers who are studying humans who have lived thousands, even hundreds of thousands of thousands of years ago.

These samples sometimes contain collagen, a useful molecule that can reveal a mine of information about human remains – how long has a person died until she was able to eat.

"Bone collagen is truly a treasure in the field of archeology," said Christina Ryder, a postgraduate student in the Department of Anthropology at CU Boulder.

Now, she and her colleagues have come up with a creative way to save this treasure.

In the research published this week in the journal Scientific reports, the group describes a new method of screening bone samples to determine if they contain collagen. Unlike existing tools that are looking for this type of fabric, the approach of the team will not damage the bones.

For anthropologists, the test could change the rules of the game, said co-author of the study Matt Sponheimer, professor of anthropology at CU Boulder.

"These remains have remained intact for thousands of years, so always destroy a sample," he said. "It's doubly tragic if you do it, and it's in vain – that's what we're trying to prevent."

It's a goal that has emerged from many hours of frustration. Several years ago, one of Sponheimer's colleagues was responsible for extracting collagen from a series of old bone samples. Collagen in the bones is a lot like a birth certificate; If scientists can find enough, they can use collagen to determine the age of a human specimen by radiocarbon dating.

But this material, which helps to maintain bones and other human tissues, does not age well either. Many skeletal remains, even those from well-preserved tombs, do not contain much.

"My student spent weeks and, in the end, months of lab trying to get nutritional information from old collagen, and the results were incredibly mediocre," Sponheimer said. "I thought to myself, there must be a better way."

It turned out that there were some. In their latest study, Sponheimer, Ryder and their colleagues discovered that they could calibrate a machine called a near infrared spectrometer to test the presence of collagen in bones.

The process is surprisingly easy, Ryder said. The instrument, which uses a portable probe, analyzes bone samples and, in a few seconds, provides an estimate of how much collagen is inside.

"I'll say the longest part of the process is typing the file name," Ryder said.

To make sure of the accuracy of their method, the researchers tested their instrument on more than 50 samples of bone crushed with known collagen concentrations. The tests correctly predicted the approximate concentrations of collagen in each of these samples. It worked with 44 pieces of whole bone, too.

Ryder added that the entire spectrometer was about the size of a briefcase, which meant that the team could carry it with it on the ground.

He has already gone through a high level dry race. Last year, Ryder traveled to Germany to meet colleagues at the Max Planck Institute of Evolutionary Anthropology. The researchers wanted to date human remains discovered in Dolni Vestonice, a unique archaeological site in the Czech Republic that houses some of the oldest known examples of figurative art in the history of humanity.

"The graduate student of this project had only six flasks of samples from human burials," Ryder said. "It was all she had, and that was all that anyone was going to have for the foreseeable future."

Thanks to its near-infrared spectrometer, researchers have been able to limit the amount of bone to be destroyed for their radiocarbon dating. The group released its results earlier this month in the press. Journal of Archaeological Science: Reports.

And, according to Sponheimer, the team's method could one day also allow them to track the bones to detect the presence of something more valuable than collagen: the old DNA.

"For those doing this job, the practical benefits are obvious," said Sponheimer.