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NewsAncient gut bugs hitched a ride with humans across the globe. A Stanford-led study published in Nature found that hundreds of bacterial species shared between two non-industrialized populations — the Hadza of Tanzania and the Tsimane of Bolivia — have co-evolved with humans since prehistoric migrations out of Africa. Alarmingly, about 60% of these ancient microbes are now rare or absent in people living in industrialized societies.
A landmark Stanford University study published in Nature reveals that the human gut microbiome has deep evolutionary roots — with many bacterial species co-migrating alongside humans as they spread across the globe tens of thousands of years ago. Researchers compared the gut microbiomes of the Hadza (Tanzania) and the Tsimane (Bolivia), two non-industrialized populations separated for millennia, and found they share over 1,200 bacterial species. Strikingly, about 60% of those species are rare or completely absent in industrialized populations.
Using deep metagenomic sequencing and population genetics analysis, the team traced the evolutionary histories of shared microbial strains — finding divergence timelines that align with major prehistoric human migrations out of Africa and into the Americas. This suggests these microbes weren't just passengers; they've been integral biological companions, passed down through generations for thousands of years.
By the Numbers:
Why it matters: The rapid loss of microbial diversity driven by antibiotics, processed diets, and sanitized living conditions may be stripping away microbes our genomes evolved alongside — potentially contributing to rising rates of autoimmune disease, obesity, and Type 2 diabetes in industrialized nations.
