麻豆淫院

Ancient bones, artifacts and texts offer numerous insights into the past, as does the chewing gum that Neolithic people chewed on and spat out long ago. Analysis of lumps of birch bark tar from ancient settlements has revealed widespread uses by Neolithic farmers, such as for assembling tools, repairing ceramics and chewing, possibly for medicinal purposes.

Birch bark tar is the world's oldest known synthetic material, made from heating birch bark over a fire until it produces a sticky, black resin. Studies have previously revealed that the tar was a common prehistoric adhesive. But archaeologist Hannes Schroeder and geneticist Anna White of the University of Copenhagen's Globe Institute and colleagues wanted to know more about other possible uses.

The team examined 30 samples of birch tar, including loose lumps and fragments of residue scraped from tools and pottery. They were taken from nine Neolithic settlements principally around lakes in the Alpine region of Europe. To uncover secrets from the past inside the material, the researchers adopted a two-pronged approach.

First, they used chemical analysis to confirm that the material was, in fact, birch bark tar. Then, they used ancient DNA analysis to look for any genetic material that might be preserved in the resin.

The scientists their findings in the Proceedings of the Royal Society B: Biological Sciences. Male and female human DNA and oral bacterial DNA were found on several chewed samples, confirming that people were chewing the tar. The team also found DNA from barley, beech, wheat, pea and hazel in these lumps, which were likely remnants from their recent meals. Analysis of the ceramic tar revealed traces of plant DNA, suggesting they were used for storage or cooking.

The tar also had other possible uses. Residue found along break lines of pottery strongly hints that it was used as glue to fix broken pieces. Additionally, tar residue was found on flint blades at the point where they would have joined a wooden handle.

Deeper insights

One of the most important aspects of this research is that it fills in major gaps in our knowledge about Neolithic communities. Human bones and teeth rarely survive the wet environment of these lake communities, but tar is water-resistant and preserves genetic material.

"This study underscores the value of integrating organic residue and ancient DNA analysis of archaeological artifacts to deepen our understanding of past cultural practices," wrote the scientists in their paper.

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