In an archeological site in southern Denmark, a student at the University of Copenhagen picked up a piece of gray and black “gum”, Run to Associate Professor Hannes Schroeder and ask :

Can we extract DNA information from here?

Although never before, Schroeder did not refuse to try. As a result, we were able to release Nature Communications on December 17th I read a story hidden in “Gumball” more than 5000 years ago.

▲5,000-year-old “gum”

This “gum” is actually a piece of chewed birch gum, mainly made by heating the birch bark. Schroeder pointed out in a paper that such small pieces of organic matter are in Scandinavian Archaeological relics in Asia are quite common, and research speculates that they are mainly used for bonding stone tools.

▲ Picture from ” The Conversation “

Researchers often find the tooth marks left by ancient people on these materials. They think this is because the gum will harden after cooling. If the ancient people want to use it, they must chew it first. At the same time, there is also evidence pointing to the medical effects of birch gum, as it contains natural antibacterial properties and may be used to treat oral and other diseases.

It is also because of its natural antibacterial and hydrophobic properties that this piece of chewing gum retains the DNA of the chewing person and the information of the oral microbial flora. According to research, the quality of the DNA information in this gum is as high as the information in well-preserved teeth and bones.

With this information, Schroeder’s team constructed the complete genome of the chewr, and concluded that the chewr is a dark-skinned woman with dark brown hair and blue eyes. The ancestor was a hunter from continental Europe. Collector.

▲ The researchers used the genetic information to restore the image of the chew. There are also mallards and hazelnuts that seem to have been eaten. Pictured from ” Online “

From an evolutionary perspective, it is generally believed that residents of northern Europe have long had light skin tone and hair color because it is more conducive to the production of vitamin D in cold and dark environments. The results of this study, however, point to the fact that this characterization was formed in the last 5,000 years.

In addition, the researchers found that the girl had lactose intolerance. This is also consistent with previous research. The academic community believes that humans have gradually developed after entering the livestock industry.Ability to digest dairy products.

It is particularly interesting that more than 60% of the genetic information found by researchers this time in “gum” is not human, and the distinguished attributions are birch, hazelnut and mallard.

Birch is easy to understand because the gum itself is the birch bark. As for hazelnuts and mallards, the researchers reasoned that they should have been eaten before the chewing gum. In addition to the “gum” itself, researchers have also found traces of these two creatures in the site environment, and previous studies have pointed out that Scandinavian residents will collect hazelnuts to eat.

In addition to DNA information, this “gum” also provides a special “oral microbiome snapshot”.

▲ Researchers used to look for microbial information in calculus. The picture comes from Sepsis

Before that, researchers have found information about ancient human oral microbes in dental calculus. However, most of the information stored in calculus represents a long-term comprehensive situation, and the traces left on this gel can provide more “aging” microorganismsInformation can be used as a supplementary material for research.

Overall, Schroeder and his students were curious at the moment, discovering a whole new source of research information for archeological researchers.

Molecular archeologist at Harvard University Christina Warinner believes that is a creative way to obtain the genetic information of the ancients. She is the gene contained in this little piece of gum. The amount of information was surprising.

Many times, we find human genes in some objects, but usually they are very, very small.

In her opinion, with the rapid development of science and technology, scientists should try more to study things that we have never imagined will be useful:

We started to realize that it turned out that there were more things left than we thought.

This inspired me to start looking for more unusual things (to study), and we may find interesting information in them.

The picture is from 《Wired》