The entire human genome decoded from a thousand year-old “chewing gum”

Researchers at the University of Copenhagen have successfully extracted the entire ancient human genome from a type of “pitch gum” made of birch wood discovered by archaeologists. This is the first time that the entire human genome has completely been extracted from materials other than human bones. Results from this new research are published in the scientific journal, Nature Communications.

Based on this information, researchers have determined that the gum was chewed by a woman. Genetic analysis revealed that the woman may have dark skin, dark hair, and blue eyes. Birch pitch is a dark brown material produced by heating birch bark. In prehistoric times, it was often used as a glue for sticking stone tools. Birch pitch had been used since the Paleolithic age. Fragments of birch pitch are usually imprinted with teeth, meaning they have been chewed. Since the pitch solidifies as it cools, it is presumed that it should have been chewed before it was used to make it ductile again.

An artist’s reconstruction of Lola, a woman who chewed the Syltholm birch pitch. Image credit: Tom Björklund.

Besides, birch pitch is also considered to be used for other uses such as relieving toothaches or other diseases because it has a medium preservative. Another inference is that prehistoric people might have used it as a toothbrush to suppress hunger or as chewing gum just for fun. This is the earliest historical evidence of chewing gum.

Notably, the researchers successfully retrieved DNA from oral microbes on this pitch, including many symbiotic species and opportunistic pathogens. DNA from Epstein-Barr virus, which can cause infectious mononucleosis or glandular fever was also found.

The ancient “gum” has great potential for studying the composition of the ancestral microbiome and the evolution of human pathogens. It helps us understand how pathogens have evolved and spread over time, and what makes them particularly toxic in specific environments. This can be used to predict the future evolution of pathogens and how to prevent or eradicate them.

References

1. https://www.nature.com/articles/s41467-019-13549-9
2. https://healthsciences.ku.dk/newsfaculty-news/2019/12/ancient-chewing-gum-yields-insights-into-people-and-bacteria-of-the-past/

Author

Sherry Hsiao