Scientific and medical communities are increasingly discovering the importance of the microbiome – the community of microorganisms residing in our bodies. But a new study finds that, compared with our closest relatives – African apes – humans have significantly less diverse gut bacteria, suggesting possible human health implications.

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Compared with many humans, apes tend to eat a more plant-based diet, a potential factor in why we have lost much of our microbial diversity.

The study, which is published in the journal Proceedings of the National Academy of Sciences, was conducted by researchers from the University of Texas at Austin, Yale University and the University of Pennsylvania.

Previous studies have shed light on the importance of gut bacteria. One such study found that gut bacteria are essential for immune cell development, while another suggested changes in gut bacteria could predict infection and inflammation.

So important is a good balance of bacteria in the gut, that Medical News Today recently reported on a study showing how fecal capsules resolved a bacterial infection in 90% of patients. The research, published in JAMA demonstrated how a capsulized version of a procedure called fecal microbiota transplantation (FMT) – whereby stool from a healthy donor is transplanted to an infected individual – is safe and effective.

But researchers from this latest study wanted to examine how the gut microbiome has changed since the diversification of humans and apes. They explain that a lack of human gut microbial diversity has also been linked to asthma, colon cancer and autoimmune diseases.

Though humans contain trillions of microorganisms, the team says the evolutionary history of our bodily ecosystems is not well known because we do not know much about the microbiomes of African apes.

As such, the team assessed the genetic makeup of bacteria in fecal samples from humans, chimpanzees, bonobos and gorillas to learn more.

After conducting their analysis, the team found that microbial diversity changed slowly and steadily over millions of years as humans diverged from apes, but this rate of change has increased recently in humans from certain parts of the world.

In detail, people from non-industrialized societies have gut microbiomes that are 60% different from those of chimpanzees, while people in the US have gut microbiomes that are 70% different.

The researchers add that previous studies have shown that, compared with several populations, people in the US have the lowest diversity of gut microbes.

Prof. Howard Ochman, study co-author from The University of Texas at Austin, explains:

”It took millions of years, since humans and chimpanzees split from a common ancestor, to become 60% different in these colonies living in our digestive systems. On the other hand, in apparently only hundreds of years – and possibly a lot fewer – people in the US lost a great deal of diversity in the bacteria living in their gut.”

The analysis reveals that, compared with the microbiomes of wild apes, ours have lost microbial diversity, and it may have something to do with a shift in our diets.

The researchers note that humans shifted to a diet with more meat and fewer plants, compared with our ape ancestors, and this could be an explanation for why we have less diversity in our gut microbiomes. They add that plants require complex ecosystems of microbes to break them down, whereas meat does not.

But why do people in the US have such different gut bacteria compared with individuals in less industrialized societies? The researchers suggest it may be down to more time spent indoors, frequent use of antibacterial soaps and cleaners, higher use of antibiotics and more births by Cesarean section (C-section).

Mothers pass good bacteria to their babies during vaginal births, so C-section deliveries could prevent babies from getting this vital good bacteria.

Prof. Ochman says this declining gut bacteria diversity “has been a trend for a long time,” adding that it is “tantalizing to think that the decrease in microbial diversity in humans is due only to modern medical practices and other lifestyle changes, but this research shows other factors over time also must have played a role.”

The researchers conclude their study by noting their results “indicate that humanity has experienced a depletion of the gut flora since diverging from Pan.”

MNT compiled an article outlining the health benefits of probiotics.