in and out

The baby poop of hunter-gatherers could unlock better gut health

The Hadza are known for their exceptional microbiomes.

A curious young African child of the Hadzabe tribe (Africa's last hunter/gatherer tribe) in Tanzania...
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Baby poop is not something you might typically think about unless you’re a new parent. But the squishy, frequently malodorous stuff is incredibly important: It’s a window into not only a baby's current health but also their well-being for the rest of their lives.

Your own bowel movements are important for your health too, but the magic really starts when you are young. A new study involving members of some of the last hunter-gatherers living on Earth reveals why you should pay more attention to what’s coming out as well as what’s going in your body.

Here’s the background — Poop contains a multitude of microorganisms — that is the bacteria, viruses, and fungi that inhabit our guts — and gives us a glimpse into the health of our microbiomes, what researchers dubbed the ecosystem of these tiny critters that make the inside of our bowel walls their home.

Infant poop, as gnarly as it might seem, is crucial to study and scrutinize. This microbial ecosystem isn’t fully established the moment we are born. It takes time for the various microbes to organize themselves into a thriving community. Microbiologists have found our microbiomes start to establish themselves during the first six months of life — in western, industrialized countries at least. These tiny communities are unique to every individual and vary depending on where a person lives and what they eat.

Once our gut microbiomes are established, they pretty much stay that way for the rest of our lives — so understanding early development is key.

Scientists know a lot about the gut microbiomes in babies growing up in industrialized countries, such as the United States, but they know far less about this same process occurring in infants living in nonindustrialized populations. In the past decade or so, researchers have also come to realize that adults in nonindustrialized areas typically have a much more diverse set of microbes established in their guts compared to those in industrialized places. And importantly, they've found a diverse set of microbiomes might be key to better health.

The gut microbiome has an influence on many aspects of the mind and body.


What's new — In a study published Thursday in the journal Science, a team of researchers collected stool samples from infants belonging to the Hadza people, a group of hunter-gatherers living in Tanzania.

The Hadza are unique in that they are among the last remaining hunter-gatherer communities in the world and they have incredibly diverse microbiomes. And because they consume almost no processed foods, they take in upwards of 100 grams of fiber per day (in contrast, Americans take in a fraction of that amount).

Researchers who study the microbiome surmise that this diet and lifestyle could be contributing to the development of the Hadza people’s robust microbiome.

“These patterns suggest that more species are lost than gained as lifestyles industrialize.”

How they did it — To tease this apart, researchers sequenced the stools of Hadza infants, which helped them identify what strains of bacteria and other organisms live within.

Then, they compared what they found to a database of sequences of infant stool samples from 18 population groups around the globe. The researchers found that, overall, most babies start out with similar types of gut microbes. Particularly, they all have a lot of Bifidobacteria. But slowly, their bacterial makeup starts to shift.

For infants living in industrialized countries, their microbiomes start to change and develop at about six months. For babies living in less industrialized environments, such as the Hadza, their microbiomes didn’t start to change until they were about 30 months old, or two and a half years.

When the scientists further scrutinized the bacterial species that thrive in Hadza infants, they found that about 20 percent of those species were novel, meaning researchers had never found them in anyone else's guts before.

The researchers found that the main driver for these shifts in gut microbes was the lifestyle — industrialized versus nonindustrialized — rather than geography.

“These data support that — similar to the adult Hadza gut — the Hadza infant gut contains extensive previously uncharacterized diversity,” the researchers write.

“Together these patterns suggest that more species are lost than gained as lifestyles industrialize.”

This is key, the researchers say, because it tells us that something in industrialized societies is causing us to lose microbial diversity, which is associated with better health.

Why it matters — The composition of our gut microbiomes is incredibly important. While researchers are still learning about all the ways that these bugs interact with our bodies, they have found that they can influence everything from how well our immune system functions to our mental health and even how well our muscles work when we exercise.

Scientists haven’t yet fully pinned down all the mechanisms through which these microbes do these jobs, but, again, they have found that a more diverse microbiome is vital. The Hadza have some of the most diverse microbiomes in the world.

The most recent work shows that in addition to Hadza adults, Hadza infants also have guts that are teeming with diverse species. In contrast, babies in areas that are more industrialized have far less diverse species.

The research is important for another reason, too. Research on the microbiome is often limited to rich countries with mostly white participants. This leaves giant gaps in our understanding of the human gut microbiome.

“The Hadza specific discoveries reported in this work exemplify the importance of studying people outside of industrialized nations and highlights the need for additional studies to provide equity in understanding microbiomes across global societies,” the researchers write.

What’s next — Researchers are currently studying how the gut microbiome plays a role in our health, specifically in chronic diseases. A common one is inflammatory bowel disease, which scientists have found mainly in industrialized countries, where the immune system goes haywire and causes ongoing inflammation in the gut.

The gut microbiome might also play a key role in many other diseases as well. Understanding what keeps our guts diverse and healthy might be crucial to preventing or treating these diseases.

“Our results also highlight the question of whether lifestyle-specific differences in the gut microbiome’s developmental trajectory predispose populations to diseases common in the industrialized world, such as those driven by chronic inflammation,” the researchers write.

Researchers have already found that factors like taking many antibiotics in the first few years of life, being born via C-section, and being formula-fed can all alter the diversity of our gut microbiome. But all of these scenarios are also life-saving in the majority of cases.

Understanding what a healthy microbiome is, and how to cultivate it, is crucial: It can help us get back on track.

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