The study of ancient humans’ microbiomes is a topic of growing interest, because it is believed that these microbiomes more closely resemble native or ‘natural’ microbiomes than the ones we have today. There have been a few studies on humans’ microbiomes at different periods of history, and another data point was added to the list last week. Researchers from Italy and California were able to measure the microbiome of a pre-Columbian human (11th century to be exact) that was mummified naturally after he died in the cold, harsh, and high elevations of the Andes Mountains in Chile. The researchers published their findings in the journal PLoS ONE.
The researchers sequenced the bacteria that were in the mummy’s colon, as well as the mummy’s feces. Strikingly, around 99% of the bacteria belonged to the Firmicutes genus, mainly dominated by Clostridia, and Turicibacter. In addition, the human appeared to have many bacteria associated with modern day diseases. For example the mummy’s microbiome contained Clostridium difficile (the cause of C. difficile infection), Trypansoma cruzi (the cause of Chagas’ disease), and many types of human papilloma virus (HPV). Finally, the researchers noted that many genes associated with antibiotic resistance were found in the mummy’s microbiome, long before these antibiotics were introduced.
This paper revealed many fascinating aspects about our ancient microbiomes. First, it is interesting to see that Firmicutes dominated our ancient flora, especially because Bacteroidetes, which are much more common in our guts today, are broadly associated with health. Also, it appears that many of the pathogens that afflict all sorts of diseases today have prehistoric counterparts, and may have been more abundant, or even more tolerable long ago. Finally, the revelation about antibiotic resistance genes show that the mutations that cause them appear common enough that they occurred naturally in thousand year old colons.