For the first time, researchers have been able to reconstruct a complete human genome without using physical remains. Instead, they used chewing gum — from the Stone Age.
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Gobs of birch pitch (tar) have been found around ancient toolmaking sites, imprinted with human teeth marks. Archaeologists say the pitch was likely chewed to help soften it before use. Recently, a chewed birch pitch excavated at the site of Syltholm on the Danish island of Lolland, estimated to be 5,700 years old, was recently used to tell the story of “Lola.” Researchers extracted Lola’s DNA and microbiome from the pitch and were able to identify the DNA of plants and animals she had likely recently consumed, as well as the DNA of her oral microbiome.
According to the results, published in the journal Nature Communications, Lola lives around 3,700 B.C. on an island in the Baltic Sea. She had recently consumed duck and hazelnuts, she was lactose intolerant and she may have suffered from gum disease.
Study co-author Hannes Schroeder explained, “This is the first time we have the complete ancient human genome from anything other than [human] bone, and that in itself is quite remarkable. What’s so exciting about this material is that you can also get microbial DNA.”
The majority of bacteria found in Lola’s oral microbiome was normal, except for those associated with severe periodontal disease. Streptococcus pneumonia was also found in her microbiome, but researchers say it’s impossible to determine from the small pitch sample whether she was suffering from pneumonia at the time. According to researchers, Lola’s lactose intolerance supports the theory that European populations were unable to digest lactose until they began consuming milk from domesticated animals.
By having the ability to sequence ancient DNA, Schroeder said, researchers will be able to better understand the evolution of the human microbiome over time.