There are some parts of the world where spitting your gum out on the street will earn you a night in jail. It's gross, it sticks to your shoes, and it doesn't go away. Consider the case of the 5,700-year-old piece of ancient chewing gum recently found in Denmark. Made from heated and processed birch pitch, this piece of gum is so well preserved that researchers were able to sequence the DNA of the careless gum-chewer who spit it out. She had dark hair, dark skin, blue eyes, and never heard of a trashcan in her life. They wouldn't be invented for a while, so it's not really her fault.
According to the study recently published in Nature Communications, researchers were able to examine the DNA of the woman chewing the gum, but also of the bacteria in the microbiome of her mouth. With this information, researchers say they can discover the common diet and diseases that were prevalent among the people living in Denmark 5,700 years ago. Researchers found evidence of DNA that resembles modern-day diseases like pneumonia, gum infections, and herpes. They also found the DNA of a Mallard duck and hazelnuts, suggesting a pretty fantastic dinner.
The archaeologists examining this particular site on the Danish island of Lolland haven't found any human remains, so this piece of chewed up gum is actually an incredibly useful window into a place and time that may otherwise be completely unknown. Carbon dating revealed the chewing gum to be approximately 5,700-years-old. This places it right at the time when people in the area moved from a nomadic hunter-gatherer way of life to a more settled, agricultural existence. This particular woman's DNA, however, showed no signs of the more recent agricultural people, suggesting that during this transitional time, hunter-gatherers may have remained genetically independent from agricultural societies.
While the constituent ingredients of modern chewing gum are industry secrets (listed on the ingredient list as "gum base," we don't really know what's in it nor would we probably want to), gum used to be made from heated tree pitch. As far back as the Pleistocene era, or "stone age," people were chewing on tree gum for basically the same reasons we use it now. Chewing tree pitch with antiseptic properties freshened breath, reduced the risk of disease, and gave people something to do before the commodification of distraction. Different trees were used depending on the region, and researchers have found tiny clumps of chewed tree pitch all over the world. In Denmark, birch trees were used. Interestingly, xylitol from birch is still used as a sweetener in sugar-free gum.
This isn't the first piece of gum that researchers have genetically sequenced. Earlier this year, researchers found DNA on a 10,000-year-old piece of gum. Now that the ability to study the DNA of these finds is becoming more commonplace, there's a lot we can learn from the refuse of our ancestors. Like the fact that we really haven't changed all that much.