Humans and other primates carry complex communities of microbes in our guts, and while we know how important these microbiomes can be for health, we still don't know very much about the evolutionary histories of this symbiotic relationship. In new work, researchers have examined the gut microbiomes of our closest primate relatives - chimpanzees and bonobos, and compared them to humans. This research assessed the bacteria found in primates and revealed specific bacterial groups that are only found in the distant ancestors of humans and primates. The investigators also determined that these ancestral microbes are quickly being lost from humans, although the reason is unclear. The researchers suggested that these changes in gut microbiomes are likely due to diet alterations. The work has been reported in Nature Microbiology.
"The working idea is that the losses we see spanning all human populations, regardless of lifestyle, were likely driven by dietary shifts that happened early in human evolution since we've diverged from chimpanzees and bonobos," explained senior study author Andrew Moeller, an assistant professor at Cornell University.
Humans have been moving away from consuming diets that contain many complex plant polysaccharides, which are found in leaves. In general, people are tending to eat more animal fat and protein, said Moeller.
This work used a metagenomic approach to identify the microorganisms that were present in a sample and the proportions of these microbes within the sample. The study authors utilized metagenomes from the guts of human and non-human primate metagenomes. This showed that many gut bacteria and their hosts have a shared evolutionary history.
Humans were found to lack about 44 percent of microbes that were found in African apes, and about 54 percent of bacteria in apes' microbiomes were gone from industrialized human populations.
This is the first study of the microbiome that has shown that many bacteria have been associated with primates and humans for millions of years, and there is a shared evolutionary history, said Moeller.
Moeller also noted that microbiome studies should include samples from many places, particularly those that are not in industrialized nations, so that the diverse composition of the human gut microbiome cam be fully characterized. It seems likely that things like diet and medications could be affecting the microbiomes of people in industrialized nations. The disruption of ancestral bacteria may have some role in diseases like autoimmune disorders or metabolic syndrome, some scientists have suggested.
Another study involving these researchers has recently shown that the microbes in a gut microbiome tend to be locally adapted to their hosts.
Sources: Cornell University, Nature Microbiology, Science Advances
