An article published in Science Advances studied the microbiome of Yanomami subjects in the Amazon with no previous record of contact with non-Yanomami – the most isolated community ever explored in the microbiome literature.

Researchers sampled the oral cavity, forearm skin, and feces from 34 Yanomami villagers. Overall, they found that the microbiome had the highest diversity ever reported in a human group. Village populations previously studied in the Amazon had less bacterial diversity than the Yanomami, suggesting that it may have been the isolation of the Yanomami that was responsible for their high-diversity microbiome. A causal relationship between microbiome diversity and lack of Western contact is possible but not confirmed by this study.

Bacterial diversity in the feces and skin were more diverse than in healthy US subjects from Colorado. Yanomami also had lower microbiome variability than US subjects, and metagenomic predictions showed distinct functional profiles in the two groups.

Oral bacterial diversity was similar in the Yanomami and US subjects, despite a different bacterial composition in the two groups.

Antibiotic resistance genes were found in the Yanomami population, even though they had no known antibiotic exposure. Researchers hypothesized that these genes may have originated from soil microbes.

Researchers say extensive functional characterization of the microbiome and resistome in nonwesternized populations is needed to tease out the effects of ‘modern practices’ on the microbiome.

Maria Gloria Dominguez Bello, an author of the paper, presented this work at the 2015 Gut Summit – See the video of session 3 here.

This work was covered widely in the media. Some coverage, however, misrepresented the conclusions of the paper by saying that Western diets and practices have a causal relationship with the lower diversity found in Western microbiomes.


Clemente, J C, et al. (2015) The microbiome of uncontacted Amerindians. Science Advances, DOI: 10.1126/sciadv.1500183