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New Mass Spectrometry Techniques Uncover Clues from Ancient Proteins

Researchers used a mass spectrometry technique to analyze glue used to repair a punch bowl once owned by Mary Washington. | Courtesy of the George Washington Foundation

Researchers can now pinpoint when early cultures began consuming animal milk and what kind of homemade glue was used to repair a punch bowl owned by George Washington’s mother using new mass spectrometry chemical analysis techniques.

Three scientists participating in a news briefing at the 2019 AAAS Annual Meeting in Washington, D.C., described advances including instantaneous analysis of artifacts and techniques to extract proteins from fossilized bones that are leading to new findings in archeology and paleontology.

Christina Warinner, an associate professor of microbiome sciences at the Max Planck Institute for the Science of Human History, is using a new application of mass spectrometry to identify milk proteins in calcified dental plaque taken from ancient Mongolians’ teeth to determine how long ago the culture adopted the practice of using milk from horses and other grazing animals.

“The first step was finding that we could recover milk protein. It decomposes very readily,” she said. Previously, archeologists relied on recovering dairy fats from pots, she said, but Mongolians didn’t use pottery. They are also nomadic, so they didn’t have settlements that could be excavated. Before modern dental hygiene practices began destroying these fascinating historical records, Warinner said, dental plaques would build up in layers over a person’s lifetime, trapping information not only about a person’s diet, but also pollen and environmental pollutants that can give clues as to what they did.

Using this analysis, Warinner’s team found the Mongolians began consuming dairy as early as 1300 BCE. “DNA will just tell you what species” something is from, she said, but “proteins are amazing because they’re highly tissue specific. That’s why we can tell it’s milk, not meat,” Warinner said. Also, using the kinds of technology we have today, DNA analysis is limited to about one million years ago, but proteins that extend even farther into the past can be analyzed, she said.

Elena Schroeter, Christina Warinner and Ruth Ann Armitage speak Friday during a 2019 AAAS Annual Meeting press briefing. | Andrea Korte/AAAS

Ruth Ann Armitage, professor of chemistry at Eastern Michigan University, is using a mass spectrometry technique called direct analysis in real time, DART, to do instantaneous analysis of historically important samples. In one case, she took a couple of strands of fabric from a museum textile to find what type of red dye was used, information that influences the type of exhibit lighting that can be used without damaging it.

“To get results instantaneously is great. We can answer questions quickly, which might be useful, depending on what your question is,” Armitage said.

Armitage also employed DART to analyze glue used to repair a small 18th century punch bowl Mary Washington had owned. She found it was a water-soluble glue made from cheese and lye, from which historians could conclude that Washington had probably kept the bowl for display purposes, since it could no longer be used to hold food.

Elena Schroeter, a paleontology postdoctoral fellow at North Carolina State University, developed a new technique to extract and analyze proteins from fossilized bones, which can clarify ancient animals’ family trees. While extracting proteins from modern bones is “pretty straight-forward,” Schroeter said, with fossils, you “also get junk — products of decay called humic substances,” that increase as the fossils age, and make it difficult to analyze their proteins.

Schroeter developed a method to remove large amounts of humic substances from samples, and when she tested it on a relatively young fossil, she was able to extract 20 bone proteins using the new method, compared with three using the old one. “I’m looking forward to seeing what it can do with older, more problematic fossils,” she said.


[Associated image: Ferry Farm, George Washington’s childhood home | J. Albert Bowden II/Flickr CC BY 2.0]



Kathleen O'Neil

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