UPPSALA, SWEDEN—Science Magazine reports that human genetic material has been recovered from 8,000-year-old pieces of birch bark pitch that were unearthed in western Sweden in the 1980s. Birch bark pitch, derived from resin, was heated and chewed to make it pliable, and used as a fastener by hunter-gatherer toolmakers. It also may have just been chewed, like gum. A team led by Natalija Kashuba, who was then a student at the University of Oslo, ground samples from three wads of the hardened resin into powder. They then detected human DNA in all three samples, from three different individuals—two female and one male. Based on the size of the tooth marks and signs of tooth wear evident in the resin, the chewers are all thought to have been between five and 18 years old. The DNA analysis also suggests the chewers were from a group known as Scandinavian hunter-gatherers, who lived in Sweden and Norway. For more on archaeology in Sweden, go to “Hoards of the Vikings.”