Gut microbes carry genetic traces of ancient human migrations
A peer-reviewed Nature study found 1,231 gut microbial species shared by the Hadza in Tanzania and the Tsimane in Bolivia. Genetic relationships are consistent with microbes travelling alongside people during ancient migrations. Many shared species are uncommon in industrialized populations, while the consequences of their loss for human health remain uncertain.
Science··Morning
Two communities share 1,231 microbial species
The gut microbes of the Hadza in Tanzania and the Tsimane in Bolivia carry genetic patterns consistent with ancient human migrations. A peer-reviewed Nature study compared present-day stool samples from these communities and identified 1,231 shared microbial species. The findings support the interpretation that some microbes travelled with people across continents.[1], [2]
The team, including Stanford University researchers Justin Sonnenburg and Benjamin Good, reconstructed microbial genomes from the samples’ DNA. Stanford’s announcement places the shared species at approximately 90 per cent of those identified in the Tsimane samples. Many are uncommon in industrialized populations.[1]
Genetic differences point to prolonged separation
For many species, microbial lineages within one community are more closely related than those compared across continents. Researchers examined identical genome segments and genetic divergence, using models of mutation and recombination to estimate when lineages separated. The pattern fits microbes accompanying human movement out of Africa and into the Americas. The historical timing is inferred from living microbes and depends on those models.[1]
The health effects of missing species remain open
Princeton University researcher Andrew Moeller, who was interviewed by NPR, raised the possibility that industrialized microbial communities are adapted to modern lifestyles. Whether restoring missing species would benefit health remains uncertain. The research compares genetic histories; it includes no treatment trial establishing a benefit from replacing microbes. Individual-level sample data remain under controlled access, and the authors emphasize Tsimane participants’ authority over their use.[1], [2]
