On an autumn day approximately 9,700 years ago, a group of individuals were encamped on the western shore of Scandinavia. These hunter-gatherers engaged in a variety of activities, including fishing, scavenging, and resource gathering.
A group of adolescents, including both boys and girls, were masticating resin to produce adhesive after consuming trout, deer, and hazelnuts. A severe gum infection known as periodontitis made it difficult for an adolescent to consume the chewy deer flesh and prepare the resin through chewing.
The DNA analysis of ingested resin, which we have conducted and have now published in Scientific Reports, provides this snapshot of the Mesolithic period, which occurred just prior to the onset of agriculture by Europeans.
Huseby Klev, which is situated to the north of Gothenburg (Göteborg), is the current name of the location. Archaeologists excavated the site in the early 1990s, and they recovered approximately 1,849 flint artifacts and 115 fragments of resin (mastic). The site’s age is estimated to be between 10,200 and 9,400 years old, as determined by radiocarbon dating. It is important to note that one of the resin fragments has been dated to the year 9,700.
The presence of tooth impressions on a portion of the resin indicates that it was consumed by children, particularly adolescents. Masticated aggregates are frequently discovered at Mesolithic sites, and they often contain tooth impressions, fingerprints, or both.
The resin fragments that we have examined were composed of birch bark pitch, a substance that has been employed as an adhesive in stone tool technology since the Middle Palaeolithic. Conversely, traditional civilizations also consumed them for medicinal or recreational purposes.
In numerous global regions, analogous applications have been documented for a variety of substances that exhibit comparable properties, such as bitumen derived from coniferous trees, resins, and other plant compounds.
DNA’s capacity to
Half of the DNA extracted from certain resins was of human origin. This is extensive when contrasted with the commonly found in ancient bones and molars.
Scandinavian human chromosomes from this period are among the earliest known. The region was previously inhabited by Mesolithic hunter-gatherers who shared a unique ancestry profile with it.
Nevertheless, the remaining half of the DNA was derived from organisms other than humans. As the mastic was discarded 9,700 years ago, the preponderance of this DNA is derived from microorganisms, such as bacteria and fungi. Nevertheless, a portion of the birch bark pitch was ingested by a human as a result of the presence of microbes in the mouth and detritus from the human’s previous food consumption.
Analyzing all of this DNA is a novel and challenging endeavor. We were obligated to develop novel analytical strategies and adapt existing computing instruments. This work has therefore inspired the creation of a new methodology for this form of analysis.
This entails the attempt to determine which DNA fragments are associated with pathogens (hazardous microorganisms) by mining the DNA using a variety of strategies to characterize it and assembling brief DNA fragments into longer ones using machine learning techniques. It also entails a comparison of the data to the conditions observed in the jaws of contemporary individuals with periodontitis and tooth decay (caries).
Organisms that are pronounced
We identified the diverse array of microorganisms that naturally inhabit the oral cavity, which is consistent with the expected composition of an oral microbiome. Additionally, traces of bacteria that are believed to be associated with systemic diseases such as endocarditis and Hib disease, as well as conditions such as caries or tooth decay (Streptococcus mutans), were identified. Bacteria that could induce abscesses were also present.
Although the prevalence of these pathogenic microorganisms increased, their levels did not significantly exceed those expected in a healthy oral microbiome. Consequently, there is a lack of definitive evidence that connects group members to maladies associated with these microorganisms.
Nevertheless, we did discover a significant quantity of bacteria that are linked to a severe periodontal disease known as periodontitis. We concluded that the girl who chewed one of the resin fragments had likely suffered from periodontitis with a probability exceeding 75% when we implemented a machine learning strategy, specifically Random Forest modeling.
DNA from organisms that were larger than bacteria was also identified. DNA traces were detected in brown trout, red deer, and hazelnuts. It is highly probable that the adolescents had been consuming material to obtain this DNA prior to consuming the birch pitch.
However, it is crucial to exercise caution, as the precise results we observe are contingent upon the quality of the comparison data at our disposal. The assembly of a high-quality eukaryotic genome is more complex due to the larger and more intricate genomes of eukaryotic organisms, which include plants and animals, in comparison to microorganisms.
eukaryotic genomes are present in resin samples in a diminished quantity and of inferior quality. Therefore, although it is feasible that the brown trout in question does not exactly correspond to the salmon family’s species name, it is certain that it is this species.
Fox DNA was also prevalent; however, its interpretation is more challenging. Although it is feasible that these adolescents consumed fox flesh, they may have also employed fox tendons and pelt for textile purposes. It is also conceivable that the fox DNA entered the resin as a consequence of territorial marking after its expulsion.
However, the acquisition of these compelling artifacts of Stone Age human civilization certainly represents a substantial improvement in our understanding of the subject. It is possible that additional unanticipated discoveries may be discovered through additional analysis.
