- Birch pitch
- 9,880-9,540 year(s)
- Sweden ()
Birch pitch is a blackish-brown, gum-like substance created by heating the bark from birch trees. It was widely used as a form of adhesive in the Neolithic era to attach ("haft") worked stone to wooden handles to form tools and weapons as well as to repair broken ceramic vessels and plug holes in canoes, with evidence of its use as a "glue" emerging in Eurasia as far back as 200,000 years ago by Neanderthals. Owing to teeth impressions found in many examples, it's thought that the tar was probably chewed to make it more pliable for manipulation, however it's also widely believed that ancient people chewed the substance to benefit from its antiseptic qualities and to relieve toothache; it may have also been masticated to keep teeth clean and to stave off hunger, and perhaps simply because people enjoyed it, as with modern chewing gum. Examples of it being chewed date back at least 10,000 years; birch pitch excavated in western Sweden, aged at 9,880–9,540 years old, was reported in the journal Communications Biology on 15 May 2019.
An added archaeological benefit of ancient chewing gum is the DNA and bacteria that get trapped within the substance while being masticated. One such piece of chewed-up birch pitch was found in mud on the Danish island of Lolland and assessed to be approximately 5,700 years old by scientists from the University of Copenhagen (Denmark), as reported in the journal Nature Communications on 17 December 2019. The gum was so well preserved that scientists were able to extract the complete genome of the young woman that chewed it, the first time this has been achieved using non-human remains. With a complete genome, they were able to determine key physiological traits of the Stone Age chewer, including that she had dark skin, dark hair and blue eyes. The human was nicknamed "Lola" after the island where she was discovered. There were also traces of animal and plant DNA, such as duck and hazelnuts, embedded in the gum, which could have formed part of Lola's diet. The study was a collaboration between the Globe Institute at the University of Copenhagen, the National Museum of Denmark and the Museum Lolland-Falster (all Denmark), and was led by Theis Z T Jensen and Hannes Schroeder.