I love the spectacular symbiosis of my vegetable garden as harvest time approaches. Beanstalks spiral up cornstalks, their tendrils teasing nearby tomato…
We can learn about life, past and present, anywhere we find DNA and determine its sequence. DNA Science has described intriguing sources of environmental DNA, aka eDNA: DNA in Strange Places: Hippo Poop, Zoo Air, and Cave Dirt and A Glimpse of the Ocean’s Twilight Zone Through Environmental DNA.
Human remains also harbor bits of DNA that can reveal how people lived long ago.
A recent report in PLOS ONE analyzes DNA from an adenovirus and a herpes virus discovered in preserved feces – coprolites – from 5,500 to 7,000 years ago at an archaeological site in Japan. The findings suggest that those people might have suffered from similar infections to humans today.
A second recent report uncovers clues in preserved chewing gum, reminding me of Flintstones gummy vitamins. (See A Brief History of Flintstones Vitamins).
About 9,700 years ago, a group of teens were hunting, gathering, and fishing along the western coast of Scandinavia, north of what is today Göteborg. They chewed a concoction of hardened birch tar, the preserved lumps bearing bitemarks that suggest the stuff was used as a chewing gum of sorts, perhaps also as an adhesive in construction. An international research team published their findings on the Mesolithic gum in Scientific Reports.
DNA preserved in the gum revealed a diet of brown trout, deer, and hazelnuts, with lesser amounts of apple, mistletoe, red fox, grey wolf, duck, and limpet, with no evidence of Fred Flintstone’s preferred Bronto Burgers.
Bacterial DNA sequences ringing a tooth suggest that one of the kids had periodontitis, with the microbial genetic material from infected gum pockets persisting after the soft tissue degraded. He must have suffered while chewing the gum and the stringy, tough venison. The people likely relied more on their teeth to grip, cut, and tear materials than we do today with so many tools.
The gum – called “mastic” – comes from an archaeological site, Huseby Klev, on the island Orust in western Sweden. Excavation began about three decades ago, when researchers discovered stone tools with the chewed resin, dating to about 9,700 years ago. The material harbors “a richness of DNA sequences,” said Emrah Kırdök, from Mersin University in Turkey, who originated the study while doing postdoctoral research. The snippets of ancient DNA are highly similar in sequence to those found in human dental plaque today.
The work was technically challenging. “We had to apply several computational heavy analytical tools to single out the different species and organisms,” and adapt them to working with ancient DNA, said Andrés Aravena, from Istanbul University.
“This provides a snapshot of the life of a small group of hunter-gatherers on the Scandinavian west coast. There are other well-established methods to work out nutrition and diet relating to the Stone Age, but here we know that these teenagers were eating deer, trout, and hazelnuts 9,700 years ago, while at least one of them had severe problems with his teeth,” added team leader Anders Götherström, at the Centre for Palaeogenetics of Stockholm University and the Swedish Museum of Natural History.
The teens were in sore need of a dentist. The presence of DNA sequences from Treponema denticola, Streptococcus anginosus, and Slackia exigua indicate tooth decay, and from Streptococcus sobrinus and Parascardovia denticolens, periodontal disease.
I had laser surgery for periodontal disease a few months ago – I wonder if the species blasted out of my gum pockets matched those in the stone age teens. Without toothpaste, anti-microbial mouthwash, dental floss, and water piks, I suspect the Mesolithic human teeth wouldn’t have lasted even a short lifetime.