Researchers at Stanford University have revealed that indigenous Tsimane in Bolivia share 1,231 bacterial species with Hadza in Tanzania, accounting for roughly 90 percent of the Tsimane microbiome. Published in the journal Nature, the genetic findings highlight a microbial loss in industrialized populations.
Industrialized Societies Lack Rare Bacterial Species Shared by Traditional Populations
- Microbial Depletion: About 60.2 percent of the bacterial species shared between the Tsimane and Hadza are either rare or completely missing in industrialized societies.
- Evolutionary Timeline: Genetic tracking of 636 shared bacterial strains reveals common ancestors dating back roughly 17,000 years, aligning with prehistoric human migration patterns.
- Dietary Complexity: Recent laboratory studies demonstrate that gut bacteria rely on complex, interdependent community structures rather than simple dietary inputs alone to process nutrients.
Deep Sequencing of Tsimane and Hadza Microbiomes
The study, led by Stanford University and published in Nature, relies on deep sequencing of 133 stool samples collected from 85 adult Tsimane individuals in Bolivia between 2009 and 2012–2013. This genetic screening yielded 12,746 microbial genomes grouped into 1,408 total species.
When cross-referenced with data from Hadza populations in Tanzania, the comparative analysis showed that the two groups share 1,231 bacterial species. This overlap constitutes 87.4 percent of the total species cataloged in the Tsimane cohort. Tracing the evolutionary paths of 636 shared strains indicates that these microbial lineages diverged roughly 17,000 years ago, mirroring early human migrations out of Africa and into the Americas.
Industrialized Populations and the Missing 848 Bacterial Species
The contrast between traditional lifestyles and modern urban environments remains stark. Out of the 1,231 species shared by the Tsimane and Hadza, 848 species—representing 60.2 percent—are virtually absent or extremely rare in industrialized populations.
Earlier research demonstrated this disparity by measuring overall species richness. A typical Hadza individual hosts an average of 750 distinct gut bacterial species, whereas subjects tested in California harbor only about 250 species. Despite these differences, the primary causes behind this microbial attrition in industrialized nations remain unproven, and researchers have yet to establish a direct causal link between the loss of specific taxa and chronic disease development.
| Population Cohort | Average Bacterial Species Count | Shared Lineage Retention |
|---|---|---|
| Hadza (Tanzania) | ~750 species | High overlap (~90%) |
| Tsimane (Bolivia) | ~1,408 cataloged species (total) | Baseline reference |
| Industrialized Urban Groups (e.g., California) | ~250 species | Missing 848 shared species (60.2%) |
Bacterial Interdependence and the Role of Dietary Fiber
Furthermore, microbiome data drawn from roughly 1,000 healthy adults highlighted a positive correlation between higher numbers of Enterobacteriaceae species and an elevated proportion of S. copri within non-industrialized populations. These findings underscore that dietary intake alone cannot fully account for the microbial divergence observed across global populations.
References
- Nature: Genomic insights into the human gut microbiome of traditional populations
- Nature Microbiology: Helmholtz Centre for Infection Research studies on microbial cross-feeding and carbohydrate metabolism
