 Also trapped within the gum was genetic material from one of her meals—duck and hazelnuts—along with DNA from the bacteria and viruses she harbored in her mouth. | Ancient people in Scandinavia used birch pitch as chewing gum. Scientists were able to sequence a complete human genome from a piece of birch pitch that was chewed up and spat out in southern Denmark some 5700 years ago. The chewer was female, with dark skin, dark hair, and blue eyes. 17,000-year-old puma shit from the southern Andes contains the oldest parasite DNA yet recorded. It proves pumas were infested with roundworm long before humans and their animals arrived. |  |
 | Centuries-old manuscripts are appreciated for their words and illustrations, but recent research has shown they can also be treasure troves of DNA. Scribes often wrote on parchment made from the skin of animals.
Religious pages containing oaths are rife with human microbial DNA, likely because they were often handled and kissed by clergymen. DNA played a crucial role in identifying the bones of Richard III, which were unearthed beneath a city parking lot in Leicester, England in 2012. |  |
 | Rodents of millennia past were nest builders. They collected bits from their surroundings and sealed the deal with their urine, which acts as a binder that preserves the nests for tens of thousands of years. These nests, middens, offer a snapshot of the local environment at the time they were built. Because the enamel that coats our teeth is 97% mineral, human teeth are more likely to survive through time. In 2010 genetic material from a wisdom tooth discovered in Siberia lead scientists identify the Denisovans, a little-known group that shared a common ancestor with Neanderthals and Homo sapiens. |  |
