Male Bonobo in Apenheul Primate Park, Apeldoorn, NL. Credit: Bogdan Gruia
Key points:
- New study shows humans have lost close to half of the gut bacteria found in chimpanzees and bonobos.
- Changing diets may have caused the distinction.
- Researchers speculate the disruption of ancestral flora could be playing a role in modern diseases.
A new study finds that hundreds of bacterial groups have evolved in the guts of primate species over millions of years, but humans have lost close to half of these symbiotic bacteria. The study results showed that populations of gut bacteria found in chimpanzees and bonobos—humans’ closest relatives—are rapidly being lost from human lineage.
Though the cause of these shifts in human gut microbiomes is not known, the study’s authors suspect changing diets probably caused the divergence. In particular, human diets shifted away from complex plant polysaccharides found in leaves and fruits toward more animal fat and protein.
For the study, published in Nature Microbiology, researchers analyzed 9,640 human and non-human primate metagenomes.
The results showed that 44% of clades—a bacterial group that has evolved from a common ancestor and share an evolutionary history with African apes—were absent from the human metagenomic data and 54% were absent from industrialized human populations. At the same time, only 3% of bacterial clades in African apes that did not share an evolutionary history with these hosts were absent in humans.
“This is the first microbiome-wide study showing that there are a great number of ancestral co-diversifying [shared evolution] bacteria that have been co-living within primates and humans for millions of years,” said Andrew Moeller, assistant professor of ecology and evolutionary biology and faculty curator of mammalogy at the Cornell University Museum of Vertebrates.
Still, Moeller highlighted the importance of improved sampling in human populations, especially those outside of industrial countries, in order to fully represent human gut microbiome diversity.
The discrepancy in extinct bacteria between the general human population and those from industrialized countries may point to differences related to modern diets and medicines, such as antibiotics that are known to alter microbiomes. Some researchers have even speculated that the disruption of ancestral flora could be playing a role in modern diseases, such as autoimmune disorders and metabolic syndrome.