Blood residue from ancient tools reveals clues about past
Blood residue on spear points and other ancient stone tools made by American Indians thousands of years ago is providing scientists based at the Savannah River Site with new clues about life in the Carolinas thousands of years in the past.
The research is producing interesting information that indicates what animals those early people hunted and when huge Pleistocene creatures such as mammoths and mastodons might have ceased to exist.
“The results are interesting, but they are not conclusive,” said Christopher Moore, outreach coordinator for the Savannah River Archeological Research Program. “The evidence needs to be tested further; right now, there still are a lot of unknowns.”
Moore and his colleagues are working to interpret the data from the three studies. The tools they looked at were made anywhere from 13,000 to 500 or 600 years ago. They were found at a Carolina bay at the Savannah River Site known as Flamingo Bay, at other locations in the CSRA and in the Fort Bragg area in eastern North Carolina.
Some of the tools were excavated while others were found on the ground’s surface. Some were collected without human hands touching them to help rule out contamination.
All were sent to the University of Calgary in Canada to be analyzed using a technique called crossover electrophoresis. The scientists also examined soil samples from areas surrounding some of the tools.
“It appears that when hunter-gatherers made a tool by flaking, it produced numerous microfractures in the rock,” said Moore, who has a doctorate in geoscience. “Those microfractures apparently absorb blood protein or blood residue during any kind of butchery or cutting or scraping activity. The cracks in the rocks are like tiny caves that protect the residue from the elements, and it is preserved.”
After being extracted, the residue can be tested using antisera from various beasts that are modern versions of the ones that used to roam the earth. During the three studies, residue was discovered on about 20 percent of the tools, according to Moore.
“Many of the archaeologists I know in the Southeast either don’t have any knowledge of this method or are just very skeptical,” he said. “But it’s proven science. We know it works.”
On the oldest tools from the Paleo-Indian Period, testing revealed traces of deer, rabbit, cat and bison, which were quite common.
There was no elephant residue, which would have indicated that American Indians in the Carolinas were hunting mammoths and/or mastodons back then, even though there are signs that people who lived in other parts of the country did.
“It would have been really cool to have seen that, so I was a little disappointed,” Moore said. “But it’s also interesting that it wasn’t there.”
One explanation for why signs of mammoths and mastodons didn’t show up was that the animals were extinct in the Carolinas by then. It’s also possible that not enough tools were tested to find the evidence. Yet another possibility is that the massive creatures were still around, but the American Indians didn’t hunt them very often because there was plenty of easier game to kill.
“We just don’t know,” Moore said.
Testing done on the tools from the Early Archaic Period, which was from 11,500 to about 9,000 years ago, revealed residue results similar to the findings on Paleo-Indian Period tools. Traces of doglike mammals also turned up.
Analysis using antisera, in general, didn’t identify the exact species of the animals that the residues were from. For example, the deer samples could have come from “anything from whitetail deer to elk to caribou,” Moore said.
For that reason, Moore and his fellow scientists would like to have DNA extracted from the residues and tested. They also want to study more ancient American Indian tools from different areas of the Carolinas.
Dede Biles is a general assignment reporter.