Ancient piece of chewing gum offers surprising insights into the human genome

Five thousand and seven hundred years ago, “Lola,” a blue-eyed woman with dark skin and hair, chewed on a slice of birch bark pitch. Then this woman spat out her chewing gum into the mud on an island in Denmark we call Syltholm today, where it was discovered thousands of years later by archeologists. A genetic analysis of the chewing gum has provided us with a wealth of information on this nearly six-thousand-year-old Violet Beauregarde.

This is the first time the human genome has been extracted from such data. “It’s fantastic to get a full ancient human genome from anything other than bone,” said a comment from lead researcher Hannes Schroeder.

“What’s more,” he added, “we have collected DNA from oral microbes and several important human pathogens, making it a very useful source of ancient DNA, especially for periods of time when we don’t have any human remains.”

In the pitch, researchers identified the DNA of the Epstein-Barr virus, which infects about 90 percent of adults. They also found DNA belonging to hazelnuts and mallards, which were likely the most recent meal that Lola had eaten before spitting out her chewing gum.

The birch pitch was discovered at a site called Syltholm on the island of Lolland (the inspiration for the name of Lola). “Syltholm is exceptional,” said Jensen, who worked for his PhD on the analysis. “Almost everything is covered in mud, which ensures that it is absolutely phenomenal to conserve organic remains.

“It is Denmark’s largest Stone Age site as well as the archeological finds indicate that the site’s inhabitants were extensively exploiting wild resources well into the Neolithic period when farming and domesticated animals were first brought into southern Scandinavia.”

Since the genome of Lola does not show any of the markers associated with the agricultural populations that had started to appear in this area around her period, it provides evidence of an emerging theory that hunter-gatherers lived longer than previously thought alongside farming communities in northern Europe.

Her genome supports additional theories on northern European peoples. For example, her dark skin bolsters the idea that northern populations only recently acquired their light-skinned adaptation to the low sunlight in the winter months. She was also lactose intolerant, which researchers believe was the norm for most humans prior to the agricultural revolution. Most mammals lose their tolerance for lactose once they’ve weaned off of their mother’s milk, but once humans began keeping cows, goats, and other dairy animals, their tolerance for lactose persisted into adulthood. As a descendent of hunter-gatherers, Lola wouldn’t have needed this adaptation.

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