An ancient wad of chewing gum has yielded a complete human genome, enough information for researchers to reconstruct the visage of a girl who lived 5,700 years ago in what's now Denmark.
It marks the first time a full genome has been extracted from anything other than bone, the researchers said.
"It is amazing to have gotten a complete ancient human genome from anything other than bone," University of Copenhagen associate professor Hannes Schroeder, who led the research, said in a statement Tuesday. "What is more, we also retrieved DNA from oral microbes and several important human pathogens, which makes this a very valuable source of ancient DNA, especially for time periods where we have no human remains."
The "gum" is made of birch pitch, and was chewed by a female, the analysis showed. The researchers were able to deduce enough to get a glimpse of the girl's life. Genetically, she bore closer resemblance to mainland Europe's hunter-gatherers than to her contemporary inhabitants of central Scandinavia, the researchers said in the study, published Tuesday in the journal Nature Communications.
In addition she was shown to have dark skin and hair, and blue eyes. They were also able to determine that a recent meal probably consisted of duck and hazelnuts. The gum also contained more than 40 types of microbes, The Guardian reported.
Lola, as the researchers named her _ after the island of Lolland, where the wad was found _ lived around 3,700 B.C., according to National Geographic, and was lactose-intolerant.
Birch pitch is a black-brown substance made by heating birch bark that was used as an adhesive starting in the Middle Pleistocene Era, which stretches back to between 760,000 and 126,000 years ago, according to USA Today. Small lumps bearing tooth marks have been found before and indicate that birch pitch was masticated, but DNA has only been present in fragments, such as with an 8,000-year-old piece of it found a year ago, according to Science Magazine.
The pitch was made into glue by the chewing, Science noted, and Scandinavian hunter-gatherers used it frequently to craft their tools. In addition, it may have been used as a "prehistoric toothbrush," The Guardian noted, because such tar has been found to contain juvenile tooth marks, and is known for its antiseptic properties.
Indeed, the microbiome extracted from the pitch showed that the girl may have contended with the Epstein-Barr virus, known as the chief cause of mononucleosis, the researchers said. She also may have suffered from periodontal disease, as well as the main cause of pneumonia, Streptococcus pneumoniae, The Guardian reported. The presence of these microbes did not definitively mean she was ill, however.
Also unknowable is how long she lived, or where, or when she died, National Geographic noted.
The excavation, at a site called Syltholm in southern Denmark, is being overseen by the Museum Lolland-Falster during the construction of a tunnel to connect Denmark and Germany.
"Syltholm is completely unique. Almost everything is sealed in mud, which means that the preservation of organic remains is absolutely phenomenal," said Theis Jensen, a University of Copenhagen Globe Institute post-doctoral student who both worked on the study for his Ph.D. and also participated in the excavations at Syltholm. "It is the biggest Stone Age site in Denmark, and the archaeological finds suggest that the people who occupied the site were heavily exploiting wild resources well into the Neolithic, which is the period when farming and domesticated animals were first introduced into southern Scandinavia."
Such information is invaluable in terms of learning about humanity's past in order to shed light on our present.
"Each genome contributes to this bigger story," Harvard University molecular archaeologist Christina Warinner told NPR. "And as we get more and more information, we're able to reconstruct so much more about the human past than we ever could before."
