Tree pitch has been used as a natural chewing gum for thousands of years. Chewing gum drives cheek cells into the sticky goo and preserves them once they are spit out. A wad found in Denmark dating 5700 years ago contained DNA that geneticists say was a woman with dark hair and blue eyes. The genome, or gene map of the individual, can be patched together from the pieces of DNA left in the gum. The gum also had evidence of duck and hazelnut DNA—maybe the woman’s last meal before she had some after dinner breath freshener!