Humans lack gut bacterial diversity compared to their ape ancestors

The diversity of microbes in the human body has important consequences on disease and nutrition, with less diversity often linked to autoimmune diseases, obesity, and gastrointestinal disorders. In a study published this week in the journal Proceedings of the National Academy of Sciences, researchers studied the evolution of the human microbiome by comparing the microbial communities in the gut of human’s closest relatives, the African apes, to human’s. They found that the human microbiome had much less diversity than that of African apes, and even less diversity was observed in American’s guts compared to humans in non-industrialized nations.

The scientists collected hundreds of fecal samples from wild chimpanzees from Tanzania, wild bonobos from the Democratic Republic of the Congo, and wild gorillas from Cameroon, as well as from humans living urban lifestyles in the U.S. and Europe, rural lifestyles in Malawi, preindustrial lifestyles in southern Amazon rainforests of Venezuela, and hunter-gatherer lifestyles in Tanzania.

Results of the identification of microbes found in each fecal sample showed that the human gut microbiome is significantly less diverse than that of apes, even though there are also substantial differences among the multiple ape species. These findings confirm that microbial diversity has decreased significantly during human evolution and has changed even more rapidly in humans than among ape populations.

People living in urban cities in the United States had the least microbiome diversity, which could be a result of cultural differences, differences in diet, increase in c-section prevalence, increased use of antibacterial cleaning products, and antibiotics. As we have seen in previous studies, lower levels of microbiome diversity in humans has been linked to both immune system and gastrointestinal diseases. At this point we don’t fully understand the implications that these changes in human gut diversity over time are having but it is important to better understand this as we develop new therapeutics by manipulating the microbial communities in our gut.  

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