Modern Hunter-Gatherers Have Thriving Gut Microbiome, Compared with Californians

Diversity dwindles

From these samples, Sonnenburg and his team sequenced more than 90,000 genomes from microbes found in the human gut, including bacteria, viruses that infect bacteria, and single-celled organisms from groups called archaea and eukaryotes. Some 44% of these microbial genomes had not yet been recorded in large catalogues such as the Unified Human Gastrointestinal Genome database. Among the genome sequences recovered from the Hadza samples, more than 1,000 were from bacterial or archaeal species that are new to science.

Furthermore, gut-microbe species commonly found in industrialized populations often contained genes associated with responding to oxidative damage. The team suspects chronic inflammation in the gut could trigger such damage, creating a selective pressure for those genes, says study co-author Matthew Olm, a microbiologist at Stanford. “If you have a state of chronic inflammation, it would make sense that your gut microbiome has to adapt,” he says. These genes were not detected in the Hadza microbiomes.

Samuel Forster, a microbiologist at the Hudson Institute of Medical Research in Melbourne, Australia, says that studying non-Western populations will help to build a more complete picture of the human gut microbiome and how it differs across lifestyles and regions. This could help researchers to track which species are disappearing in industrialized populations and how that affects human health, says Forster. “We have an opportunity to understand the full complement of microbes we carry,” he says. “It’s effectively avoiding an extinction event by understanding them now, before they’re lost.”

This article is reproduced with permission and was first published on June 22, 2023.