Trends like the paleo diet and probiotic supplements attest to the popular idea that in industrial societies, our digestion has taken a turn for the worse. The scientific community is gathering evidence on how the overuse of antibiotics affects our microbiome, and on what might be causing the increasing incidence gastrointestinal inflammatory disorders like Crohn's disease and colitis. Scientists are now one step closer to knowing exactly what has changed since the majority of humans were hunter-gatherers.
Yesterday, a paper published in Nature Communications found that an entire genus of bacteria has gone missing from industrialized guts. Treponema are common in all hunter-gatherer societies that have been studied, as well as in non-human primates and other mammals. Treponema have primarily been known as pathogens responsible for diseases like syphilis, but the numerous strains found in the study are non-pathenogenic and closely resemble carbohydrate-digesting bacteria in pigs, whose digestive system is notably similar to that of humans. The genus is undetectable in humans from urban-industrial societies.
The study, led by anthropologists from the University of Oklahoma and the Universidad Científica del Sur in Peru, used genomic reconstruction to compare microbes in stool samples from two groups in Peru, one of hunter-gatherers and one of traditional farmers, with samples from people in Oklahoma. Each group comprised around 25 people. This is the first comprehensive study of the full-spectrum of microbial diversity in the guts of a group of hunter-gatherers - in this case, the Amazonian Matses people.
The researchers also sought to understand how diet affects gut health: The hunter-gatherers ate game and wild tubers, the traditional farmers ate potatoes and domestic mammals, and the Oklahomans ate primarily processed, canned, and pre-packaged food, with some additional meat and cheese.
Science published a news report discussing the findings, in which co-author Christina Warinner, PhD, an anthropologist at the University of Oklahoma, is quoted as saying:
Suddenly a picture is emerging that Treponema was part of core ancestral biome. What’s really striking is it is absolutely absent, not detectable in industrialized human populations... What’s starting to come into focus is that having a diverse gut microbiome is critical to maintaining versatility and resiliency in the gut. Once you start to lose the diversity, it may be a risk factor of inflammation and other problems.
Further research is needed to answer the next question: Is there a direct link between the absence of Treponema and the digestive health and prevalence of certain diseases (like colitis and Crohn's) in industrialized humans? If so, this could be a valuable key to increasing our digestive health. It would also indicate that imitating a paleo diet is not enough to achieve a real "paleo gut."
Previously: Drugs for bugs: industry seeks small molecules to target, tweak, and tune-up our gut microbes, Tiny hitchhikers, big impact: studying the microbiome to learn about disease, Civilization and its dietary (dis)contents: Do modern diets starve our gut-microbial community?, Stanford team awarded NIH Human Microbiome Project grant, and Contemplating how our human microbiome influences personal health
Photo by AJC1