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Stone Age humans chewed birch bark pitch, or birch tar, to make a glue-like paste that could be used for tool construction and other kinds of technology. Photo by Jorre/Wikimedia Commons/CC ================================================================ May 15 (UPI) -- Scientists have recovered human DNA from 10,000-year-old chewing gum found in Sweden. The DNA is the oldest to be sequenced from the region. Researchers found the masticated lumps of birch bark pitch, a sap-like tar, among the remains of an early Mesolithic hunter-fisher site called Huseby Klev, located on Sweden's west coast. During the Stone Age, humans used the bark-derived chewing gum as a...

Chewed tar is an unexpectedly great source of ancient DNA. No one today quite understands how they did it, but people in the Stone Age could turn ribbons of birch bark into sticky, black tar. They used this tar to make tools, fixing arrowheads onto arrows and blades onto axes. And they chewed it, as evidenced by teeth marks in some lumps. These unassuming lumps of chewed birch-bark tar turn out to be an extraordinary source of ancient DNA. This month, two separate research groups posted preprints describing DNA from the tar in Stone Age Scandinavia. The two papers have...