Human Genome Recovered From 5,700-Year-Old Chewing Gum [View all]

Modern chewing gums, which often contain polyethylene plastic, could stick around for tens or even hundreds of years, and perhaps much longer in the right conditions. Some of the first chewing gums, made of birch tar and other natural substances, have been preserved for thousands of years, including a 5,700-year-old piece of Stone Age gum unearthed in Denmark.

For archaeologists, the sticky stuff’s longevity can help piece together the lives of ancient peoples who masticated on the chewy tar. The ancient birch gum in Scandinavia preserved enough DNA to reconstruct the full human genome of its ancient chewer, identify the microbes that lived in her mouth, and even reveal the menu of a prehistoric meal.

“These birch pitch chewing gums are kind of special in terms of how well the DNA is preserved. It surprised us,” says co-author Hannes Schroeder, a molecular anthropologist at the University of Copenhagen, Denmark. “It’s as well-preserved as some of the best petrous [skull] bones that we’ve analyzed, and they are kind of the holy grail when it comes to ancient DNA preservation.”

Birch pitch, made by heating the tree’s bark, was commonly used across Scandinavia as a prehistoric glue for attaching stone tools to handles. When found, it commonly contains toothmarks. Scientists suspect several reasons why people would have chewed it: to make it malleable once again after it cooled, to ease toothaches because it’s mildly antiseptic, to clean teeth, to ease hunger pains, or simply because they enjoyed it.

https://www.smithsonianmag.com/science-nature/human-genome-recovered-5700-year-old-chewing-gum-180973801/