A 5,700-Year-Old Piece of Gum Just Gave Up a Full Human Genome
Scientists sequenced a complete ancient human genome from chewed birch pitch, the first time DNA has been recovered from something other than bone or teeth.
Here’s a nice one to close out the year on: a team of researchers pulled a complete human genome out of a piece of ancient chewing gum. Not a fossilized tooth, not a bone fragment — a wad of chewed birch pitch that’s been sitting in the ground in Denmark for roughly 5,700 years.
Birch pitch is the tar-like resin you get from heating birch bark, and people used it for thousands of years as an adhesive — hafting stone tools, patching pottery, that sort of thing. Chewing it was apparently common too, maybe to soften it up before use, maybe just because people like to chew things. Whatever the reason, the habit left behind a genetic time capsule.
The researchers extracted and sequenced a full genome from the pitch, belonging to a girl who lived in what’s now Denmark during the Neolithic. Genetic markers suggest she likely had dark skin, dark hair, and blue eyes — the kind of combination that’s shown up in a few other ancient European genomes from around that period. Beyond the human DNA, the sample also contained oral microbiome material and pathogen DNA, giving a snapshot of what was living in her mouth alongside her.
Why this matters beyond one genome
The real headline isn’t really about this one individual — it’s about the method. Ancient DNA research has been bottlenecked for years by the fact that usable genetic material mostly survives in dense skeletal tissue: petrous bones, tooth roots, that kind of thing. Soft tissue, and anything organic that isn’t bone, typically degrades long before anyone digs it up.
Chewed birch pitch turns out to be an exception, probably because the tar itself has some preservative properties and the chewing process seals saliva and cellular material inside a fairly stable matrix. That’s a big deal for archaeology, because it means there’s a whole category of non-skeletal artifacts — pitch, resin, possibly other chewed or processed organic materials — that could be sequenced from sites where no bones survived at all, or where excavators simply didn’t find any.
The work was published in Nature Communications, and it’s been getting passed around in a bunch of year-end science roundups, for good reason. It’s the kind of study that quietly expands the toolbox rather than announcing some flashy result, but the toolbox expansion is arguably more useful long-term. If ancient chewing gum is a viable DNA source, museum collections and dig sites that have been sitting around for decades might have material worth revisiting.
I’ll be curious to see if this technique gets applied more broadly next year — pitch and resin artifacts aren’t rare in the archaeological record, they’ve just never been treated as a genetic goldmine before. Sometimes the biggest methodological leaps come from someone finally asking “wait, could we sequence that?”