NOV 19, 2018 10:34 AM PST

The Gut Microbiome Changes Dramatically When Hunter-gatherers Start Farming

WRITTEN BY: Carmen Leitch

Researchers have shown that the microbial community that organisms host in their digestive tract, the gut microbiome, has a major impact on the host’s health and well-being. It’s been established that environmental factors can have an influence on the composition of the microbiome, and we know that industrial societies have different microbiomes than rural ones. In a first, researchers have now shown that the gut microbiomes of closely related populations can be very different even when those people are living in roughly the same geographical area. According to the findings, the diets that people are eating because of their lifestyle appear to be a major factor in gut microbiome composition. The work has been reported in PLOS Biology.

Scanning Electron Micrograph of Enterococcus faecalis, a common gut microbe / Credit: CDC / Pete Wardell

"This study indicates that human microbiomes may have changed gradually as human lifestyle changed, and those changes can happen within a human's lifetime," said lead study author Aashish Jha, Ph.D., a postdoctoral scholar at Stanford University.

For this work, the researchers studied four groups living in the Himalayas - the Tharu, Raute, Raji, and Chepang peoples. While they all have similar ancestry, cultures, and languages, the diets of these four communities have diverged. Agricultural has been a part of the Tharu lifestyle for about the past 300 years while the Raute and Raji have only been farming for the past thirty or forty years. The last group, the Chepang, are still hunter-gathers to this day. 

This study indicated that shifts in the gut microbiome were influenced strongly by when the community ceased hunting and gathering as their way of life. 

About 10,000 years ago, humans transitioned from a nomadic way of life as hunter-gatherers and settled as farmers. That change had a profound impact on our diet, which had been a seasonal variety of berries, nuts, roots, and seeds, with some meat and fish.

Related: Major Diet Changes may Improve Microbiome Health, but Only in Kids

In this study, the researchers examined how that lifestyle change might have affected the gut microbiome. The team assessed the microbial composition of the four different Hiumalayan groups over two months, by collecting stool samples from 56 study participants in those populations and ten North Americans with European ancestry. They also recorded lifestyle data including diet, alcohol and tobacco use, medications and health status, and environmental variables.

The samples revealed four types of gut microbiome compositions, which paralleled the transition from hunter-gatherer to farmer. In the Chepang hunter-gatherers, bacteria called Ruminobacter and Treponema were abundant, which is common in foraging populations. Those bacteria phyla are found in decreasing levels as hosts move further from the hunter-gatherer lifestyle. In an industrialized society like North America, those bacteria are rarely found. Instead, phyla like Actinobacteria and Verrucomicrobia are present in industrial populations (and nearly absent from hunter-gatherers).

The data from the Raute and Raji groups indicated that it only took a few decades for major shifts to occur in the human microbiome. We don’t yet know what that means of human health.
"We have always thought of humans as human DNA and the collection of humans cells that we walk around with," said senior author Justin Sonnenburg, Ph.D., associate professor of microbiology and immunology at Stanford. “But now we know that we have this microbial identity and that microbial portion of our biology is malleable. It can change over really short time periods."

The research continues, as the investigators search for the cause of the microbial shift. Right now, the sources of drinking water that communities use appear to be a factor. The scientists are also planning to assess diet in more detail.

"As the world is urbanizing rapidly, our microbiomes are also changing rapidly," added Jha. "So, if we don't study the traditional societies today, 20 years down the road we may be too late."

Learn more about how the microbiome influences health and disease from the video.

Sources: via Stanford University, Microecology, Cell ReportsPLOS Biology

About the Author
  • Experienced research scientist and technical expert with authorships on 28 peer-reviewed publications, traveler to over 60 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
APR 16, 2020
APR 16, 2020
How Many COVID-19 Cases Have There Really Been?
It's widely accepted that we don't have a good idea of how many COVID-19 cases are circulating, so researchers are using ...
APR 19, 2020
Genetics & Genomics
APR 19, 2020
Two New Viruses IDed in Brazilian Patient Samples
After an assessment of blood samples collected in Brazil between 2013 and 2016, scientists have found two new species of ...
APR 19, 2020
APR 19, 2020
SARS-CoV-2 Aerosols May Travel up to 13 Feet
SARS-CoV-2 has now caused tens of thousands of deaths worldwide, and hundreds of thousands of infections.
MAY 20, 2020
Cell & Molecular Biology
MAY 20, 2020
Researchers Detect a Vulnerability in Viruses
Myriad organisms share this planet, and there is an ongoing evolutionary arms race between competing traits or species, ...
MAY 25, 2020
MAY 25, 2020
The Symbiotic Bacteria That Stow Away in Ship-Destroying Clams
Shipworms are known as the 'termites of the sea.' They are not actually worms; these infamous mollusks that have brought ...
JUN 30, 2020
Plants & Animals
JUN 30, 2020
Consequences of Sixth Mass Extinction Threaten Humanity
Many scientists have taken note of the rapid decline many of the world species, and several have declared that Earth's s ...
Loading Comments...