Research press release


Nature Communications

Genetics: Ancient ‘chewing gum’ reveals human genome and oral microbiome



今回、Hannes Schroederたちの研究グループは、カバノキの脂標本に含まれるヒトDNAの塩基配列を解読して、このDNAが女性のものと判定した上で、いくつかの遺伝子の遺伝的変異を根拠として、この女性は、黒い髪で、肌が浅黒く、青い目をしていた可能性が高いことも明らかにした。Schroederたちは、このヒトが、スカンジナビア半島の中央部の狩猟採集民よりもヨーロッパ大陸の西部の狩猟採集民に近縁だったと考えている。また、カバノキの脂標本に含まれるヒト以外の古DNAの解析では、口腔マイクロバイオームに特徴的な細菌種が検出され、その一部は、(歯周病に関係すると考えられている)Porphyromonas gingivalisなどの既知の病原体だった。さらに、植物種(例えばヘーゼルナッツ)や動物種(例えばマガモ)のDNA配列も特定できたが、Schroederたちは、これらの植物と動物が直前の食事の残りかすだとする考えを示している。

The entire genome of a 5,700 year-old human from Denmark has been obtained from a specimen of chewed birch pitch, reports a study published this week in Nature Communications. An analysis of plant, animal and microorganism DNA also contained within the pitch provides insights into the oral microbiome and potential sources of the individual’s diet.

Birch pitch is obtained by heating birch bark and has been used as an adhesive since the Middle Pleistocene (approximately 760,000 to 126,000 years ago). Small lumps of this material have been found at archaeological sites and have often included tooth imprints, which suggests that they were chewed.

By sequencing the human DNA contained within the birch pitch specimen, Hannes Schroeder and colleagues determined the individual’s sex as female and, based on genetic variation in several genes, find that she likely had dark hair, dark skin and blue eyes. The authors suggest that she was more closely related to western hunter-gatherers from continental Europe than hunter-gatherers from central Scandinavia. In an analysis of the non-human ancient DNA found in the birch pitch, the researchers detected bacterial species characteristic of the oral microbiome, some of which are known pathogens such as Porphyromonas gingivalis (implicated in gum disease). In addition, DNA sequences could be mapped to plant and animal species such as hazelnut and mallard, which the authors propose were left over from a recent meal.

doi: 10.1038/s41467-019-13549-9

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