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Study Suggests Gut Bacteria Traveled With Humans Across Continents
Confirmed
In Short: A new study published in Nature suggests that certain gut bacteria have co-evolved with humans over millennia, traveling with them across continents.
Researchers from Stanford University, led by Justin Sonnenburg, found that the Hadza hunter-gatherers in Tanzania and the Tsimane forager-farmers in the Bolivian Amazon share nearly 90% of their gut bacteria, despite living thousands of miles apart.
Sonnenburg explains that if humans have been inhabited by very similar microbes over a long period of time, it suggests that our human genomes may have come to expect a certain set of microbes and their functions.
The study relied on stool samples from both groups, revealing that both the Hadza and Tsimane microbiomes were markedly different from those of city dwellers, even those living nearby.
Sonnenburg and colleagues previously completed a metagenomic sequencing on Hadza samples, showing that the average Hadza individual has about 750 species in their microbiome, while the average Californian has a mere 250.
The findings suggest that some strains of gut bacteria have long coexisted with humans, possibly to their mutual benefit.
Other researchers not affiliated with the paper say the hypothesis is intriguing but not yet proven, and that perhaps there's a reason these microbes tend not to appear in city dwellers' guts.
Andrew Moeller, an associate professor of evolutionary biology at Princeton University, suggests an alternative idea: the industrialized microbiome profile may actually be adapted to an industrialized lifestyle.
The study also highlights the potential health implications of losing ancestral microbial taxa, as biodiversity loss in the gut may lead to significant issues for human biology to adjust to and accommodate.
What this adds
The study's findings suggest that certain gut bacteria have co-evolved with humans over millennia, traveling with them across continents, which is consistent with prior WarpBeat coverage.
Background
A new study suggests that certain gut bacteria have co-evolved with humans over millennia, traveling with them across continents.
Researchers have uncovered evidence suggesting that ancient animals may have evolved much earlier than previously thought based on fossil records.
What's confirmed
- Researchers from Stanford University, led by Justin Sonnenburg, found that the Hadza hunter-gatherers in Tanzania and the Tsimane forager-farmers in the Bolivian Amazon share nearly 90% of their gut bacteria, despite living thousands of miles apart.
- Sonnenburg explains that if humans have been inhabited by very similar microbes over a long period of time, it suggests that our human genomes may have come to expect a certain set of microbes and their functions.
- The study relied on stool samples from both groups, revealing that both the Hadza and Tsimane microbiomes were markedly different from those of city dwellers, even those living nearby.
- Sonnenburg and colleagues previously completed a metagenomic sequencing on Hadza samples, showing that the average Hadza individual has about 750 species in their microbiome, while the average Californian has a mere 250.
- The findings suggest that some strains of gut bacteria have long coexisted with humans, possibly to their mutual benefit.
- Other researchers not affiliated with the paper say the hypothesis is intriguing but not yet proven, and that perhaps there's a reason these microbes tend not to appear in city dwellers' guts.
- Andrew Moeller, an associate professor of evolutionary biology at Princeton University, suggests an alternative idea: the industrialized microbiome profile may actually be adapted to an industrialized lifestyle.
- The study also highlights the potential health implications of losing ancestral microbial taxa, as biodiversity loss in the gut may lead to significant issues for human biology to adjust to and accommodate.
What's still developing
- Studying which microorganisms have been long-term residents of the human gut and may have co-evolved with humans 2, 7, 8 could provide insights into how microbial biodiversity loss affects human health.
- Our findings indicate that a diverse gut microbiome co-migrated with humans worldwide and has persisted over millennia.
- Paleontologists studying Cretaceous fossils have repeatedly found that the teeth of many ancient animals contain more of a heavier carbon isotope, carbon-13, than their presumed plant-based diets would predict.
- Image credit: Forster et al., doi: 10.3389/fevo.2026.1895247.
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