The porous bones and teeth by their nature constitute a kind of “trap” for the DNA of the mammals from which they were taken, as well as for DNA that comes from “microbial colonization or from human use”, as there are traces of blood sweat or saliva on them.
Traces of vein on a necklace carved from a deer tooth thousands of years ago made it possible to determine the date this piece dates back to and to obtain information about its owner, thanks to the use of a new DNA extraction technique.
A study published this week in the scientific journal Nature showed that the necklace belonged to a woman about 20,000 years ago.
The study, conducted by researchers from the German Max Planck Institute for Evolutionary Anthropology, indicated that “pieces made of stones, bones and teeth are important in understanding the human approach to living, behavior and culture in the Ice Age,” more than 12,000 years ago.
A large number of these pieces are available, but it is difficult to link them to a specific individual, unless they are found inside a coffin, which is very rare.
The Max Planck team was able to overcome this difficulty by using, for a test, a non-harmful technique to extract DNA from a necklace found in the Siberian Denisova Cave, which is famous for housing a number of human species for about 300,000 years.
This piece is a small flat disc, two and a half centimeters long, with a hole that allows it to be placed as a necklace. It is carved from the tooth of an antelope, which is one of the largest species of deer.
The porous bones and teeth by their nature constitute a “sort of trap” for the DNA of the mammals from which they were taken, as well as for DNA derived from “bacterial colonization or from human use”, as there are traces of blood sweat or saliva on them.
The researchers tested a range of chemical solutions to extract DNA from samples of bones, animals and teeth found at archaeological sites, and ruled out techniques that would damage the surface of the samples.
The researchers adopted a solution based on sodium phosphate and placed the necklace in it, and used it as an incubator for parts of the DNA, which they subjected to different temperatures. In order to avoid anything that might contaminate the necklace, it was extracted with gloves and immediately placed in a sealed bag.
DNA samples belonging to humans and antelopes made it possible to date them between 19,000 and 25,000 years. It was also established that the necklace was made or used by a woman, and that it belonged to a human group from northern Eurasia, whose location was previously located in eastern Siberia.
The study authors believe that their method will allow in the future to combine cultural and genetic analyzes of objects made of bone, provided that excavation protocols are applied systematically to reduce the potential for human contamination of the samples.