Ancient 'chewing gum' reveals life of young Stone-Age girl

Doyle Rice | USA TODAY

Some 5,700 years ago in present-day Denmark, a young girl chewed a wad of "chewing gum," then spat it out.

While her remains have not been found, the chewing gum – actually a bit of birch bark – was recently discovered and analyzed.

Amazingly, the entire genome of the child was determined, along with her DNA, according to a new study published Tuesday.

The DNA in the gum was so well preserved that researchers were able to get a glimpse of the girl who had chewed it and a snapshot of her life, according to Science magazine. The child had black hair, blue eyes and dark skin. Her most recent meal included duck and hazelnuts.

‘It is amazing to have gotten a complete ancient human genome from anything other than bone," said study lead author Hannes Schroeder, an archaeologist at the University of Copenhagen.

The study authors also suggest that she was more closely related to western hunter-gatherers from continental Europe than hunter-gatherers from central Scandinavia.

Schroeder told the Guardian that "the preservation of the gum is quite extraordinary. We didn’t expect to get the whole genome.”

He added, "what is more, we also retrieved DNA from oral microbes and several important human pathogens, which makes this a very valuable source of ancient DNA, especially for time periods where we have no human remains."

The gum, a black-brown substance known as birch "pitch," was made by heating birch bark and was used as an adhesive since the Middle Pleistocene Era (approximately 760,000 to 126,000 years ago). Small lumps of this material have been found at archaeological sites and have often included tooth imprints, which suggests that they were chewed.

According to the study, the results highlight the potential of chewed birch pitch as a source of ancient DNA. In addition, birch pitch "can help us understand how pathogens have evolved and spread over time, and what makes them particularly virulent in a given environment," Schroeder said. "At the same time, it may help predict how a pathogen will behave in the future, and how it might be contained or eradicated."

The lump of ancient gum, about 3/4 of an inch long, was discovered during archaeological excavations on Lolland Island, prior to construction on a tunnel that will connect Denmark to Germany.

The study was published in the peer-reviewed British journal Nature Communications.