Modern humans may be losing microbial diversity, show teeth samples from Bronze Age

Higher diversity of bacteria linked to gum disease found in 4,000-year-old teeth found in limestone cave

Ancient human teeth can also provide information about how the oral microbiome evolved over the years. Representative photo: iStock

Researchers looking at Bronze Age tooth samples found that the bacteria in our mouths were once more diverse. The well-preserved microbiome of 4,000-year-old teeth from limestone caves suggests modern humans are losing microbial diversity, according to a new study.

Old tooth samples contain higher diversity of bacterial strains Tannarella Forsythia – A bacterium linked to gum disease – compared to modern humans, the study published in the journal Molecular Biology and Evolution famous.

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“Although these modern samples come from Europe, Japan and the United States, these strains from a single ancient mouth are genetically more distinct than any pair of modern strains in our dataset. The two sample teeth contained distinct strains Tannarella Forsythia” Iseult Jackson, a doctoral student and lead author of the study, said in a statement.

This is because biodiversity loss can have a negative impact on the oral environment and human health, she added.

The new study also adds data on how the human oral microbiome evolves over time. Currently, three-quarters of published ancient oral metagenomes are from the past 2,500 years, with few complete genomes from before the Middle Ages.

Currently, researchers have a limited understanding of prehistoric bacterial diversity and how they responded to recent dietary changes, such as the expansion of agriculture that began about 10,000 years ago. Ancient human teeth can also provide information about how the oral microbiome evolved over the years.

In the new study, researchers recovered bacterial genomes from teeth found in a mass of skeletal remains excavated from a limestone cave in Killara, County Limerick, Ireland.

Team discovery There was no evidence of caries on the sample teeth, while one root produced a large number of sequences Streptococcus mutans — Bacteria involved in causing decay.

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The research team recovered the first ancient Streptococcus mutans Genomes and two different strains Tanella forsythia. They also found that both species have undergone dramatic changes over the past 750 years.

“We were very surprised to see such a large number of amoeba “This tooth is 4,000 years old,” Lara Cassidy, assistant professor at Trinity College Dublin and senior author of the study, said in a statement.

She added that this suggested the man had a high risk of tooth decay before his death.

However, the team found no other Streptococcus species.According to the paper, this shows Streptococcus This persons outcompetes other species, resulting in a pre-disease state.

Their success and expansion has been linked to the growing popularity of sugar. “Streptococcus mutans are very good at exchanging genetic material between strains, Cassidy explained, adding that this exchange would allow beneficial innovations to spread to individual strains. amoeba Bloodlines, rather than one bloodline becoming dominant and superseding all other bloodlines.

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On the other hand, there is only one lineage Tannarella Forsythia Dominate the world Now, suggestion One strain in particular has some genetic advantage over others.

The research team noted that since the industrial era, Tanella forsythia The genome acquired many new genes that help it colonize the oral environment and cause disease.

The findings support the vanishing microbiome theory, which suggests that our ancestors' microbiomes were more diverse than ours today, and that this loss of diversity could lead to chronic disease.

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