Happy Tuesday, Friends!
Over the last few weeks, I’ve discussed the recently approved COVID vaccines. So, this week, instead of looking to the future, I’d like to go way…way back in the past.
What would you do if you found a small hunk of brownish-black birch pitch in the ground? Frankly, I probably wouldn’t want to pick it up. Especially since I now know that Stone Age people in Scandinavia used to take the bark of birch trees, heat it up, and then use the resulting goo for glue or chewing gum.
A hunk of this Stone Age chewing gum was found by archeologists from the Museum Lolland-Falster at the Syltholm site on Lolland, which is an island off of Denmark. Archeologists are all about picking things up from the ground, and I’m glad they did.
Why am I excited about 5,700-year-old chewing gum?
Because, for the first time, Scientists were able to extract ancient human genetic material in the form of deoxyribonucleic acid (DNA) from something other than bone.
Here is a video where scientists talk about extracting DNA from bone, but briefly:
- Ancient DNA is fragmented – and often mixed with all sorts of other DNA, so scientists work in a clean room to protect the delicate DNA.
- Then, the sample is ground up, added to a salt solution with helps to protect the DNA. Then, a detergent, such as SDS (sodium dodecyl sulfate), is added to help break down the sample to release the DNA.
- Any proteins in the sample are separated but adding a salt such as ammonium or by adding an enzyme that digests (chews up) the proteins.
- Then, they add ice-cold ethanol or isopropanol to clean and precipitate the DNA.
- Then, they further wash and clean the DNA with more alcohol and resuspend it in a water solution, readying it for DNA sequencing. The video above explains a bit more about sequencing.
Fascinating things scientists learned from this ancient birch-pitch chewing gum:
- The person who chewed the gum 5,700 hundred years ago was a girl with blue eyes, dark skin, and dark hair.
- She’d just eaten duck and hazelnuts, based upon the traces of plant and animal DNA from her mouth that were trapped in the pitch.
- She was lactose intolerant, so it was unlikely she chased down her duck meal with a glass of milk.
- There were also traces of bacteria in the sample, and there were indicators that the girl suffered from early gum disease. This along with evidence from other sites leads scientists to believe that ancient people used to chew birch pitch to clean their teeth or to relieve a toothache.
All in all, not only was this an advance in the science DNA extraction, but it gave scientists a little window into the life of a girl who lived once upon a time in Denmark.