We’re all teeming with microbes. We’ve got guts full of them, and they’re crawling all over our skin. These tiny, ancient life forms have evolved with us. And over the last couple of decades, scientists have come to realize just how important they are to our health and well-being. They help extract nutrients from our food, influence the way our immune systems work, and can even send signals to our brains that play a role in our mental health.
But some researchers believe our microbiomes are in crisis—casualties of an increasingly sanitized, industrialized, and antimicrobial way of life. Disturbances in the collections of microbes we host have been associated with a whole host of diseases, ranging from arthritis to Alzheimer’s.
“It’s very clear in industrialized nations we have lost many species that were probably fundamental to human evolution,” says Justin Sonnenburg, a microbiome scientist at Stanford University. “They’ve just become extinct.” Some have seemingly disappeared before we’ve even had a chance to figure out what they do.
Some might not be completely gone, though. Scientists believe many might still be hiding inside the intestines of people who don’t live in the polluted, processed, and antimicrobial-laden environment that most of the rest of us share. They’ve been studying the feces of people from hunter-gatherer societies like the Yanomami, an Indigenous group in the Amazon, who appear to still have some of the microbes that other people have lost.
And so the race is on to find those missing microbes. Both academics and companies are building catalogues of microbes seen in hunter-gatherer societies, and attempting to re-create this microbial brew as a treatment for people in industrialized societies. The hope is that with the proper mix of microbes, many people might gain protection from disorders, like depression and metabolic disease, that seem to affect people living in industrialized societies at much higher rates. But there is a rather major catch: we don’t know whether those in hunter-gatherer societies really do have “healthier” microbiomes—and if they do, whether the benefits could be shared with others.
At the same time, members of the communities being studied say some projects aren’t being done ethically or equitably. Even recent research projects have taken biological samples without consent and attempted to artificially manipulate the way hunter-gatherers eat and live, says Shani Mangola, a member of the much-studied Hadza society in Tanzania. He and others are concerned about the risk of what’s called biopiracy—taking natural resources from poorer countries for the benefit of wealthier ones.
[...] Those of us who live in industrialized societies have changed the habitats of our gut microbes to a fairly drastic degree. We use antibiotics and antibacterials and eat a diet of novel ingredients and heavily processed foods.
As a result, microbiologists believe, we’ve been killing off some of the microbes that humans once carried. Compare modern-day fecal samples with ancient ones, and there are clear differences. The microbiomes of today are less diverse, with more of some bugs and fewer of others. Scientists believe that some of the ones that are missing have very important functions, like breaking down certain carbohydrates and producing chemicals that might be important for gut health.
Some people call it a great extinction. And the decline in these microbes has been linked to an uptick in a range of chronic diseases like asthma, diabetes, and inflammatory bowel disease.
Aleksandar Kostic, a microbiologist at Harvard Medical School, wants to know what microbes our ancestors did have. A couple of years ago, he and his colleagues looked for microbial DNA in eight samples of ancient human feces collected from the southwestern United States and Mexico. These remains, known as paleofeces, were estimated to be between 1,000 and 2,000 years old.
When Kostic and his colleagues compared the fossilized poo with modern-day microbiome samples from people from eight different countries, they found significant differences. But some samples were more similar than others.
Specifically, modern-day samples from people who live in “nonindustrialized” communities had a lot more in common with the ancient feces. “The paleofeces and the Yanomami samples almost matched,” says Emma Allen-Vercoe, a microbiologist at the University of Guelph in Canada, who was not an author of the study.
[...] “Taking advantage of an Indigenous population and using their microbes to try to reinstate health in somebody from a wealthy, industrialized nation, I think, is a problematic thing to do,” says Sonnenburg. He doesn’t think such experiments should never be done—just that the ethical implications should be thoroughly explored, and that the Hadza should be fully informed and consent to the research.
[...] The Yanomami have had experiences similar to those of the Hadza. “They’re angry that scientists have come, taken their samples, and never come back,” says Good. The results of the research aren’t shared with them. And neither are any potential profits.
He is working to redress that with the Yanomami Foundation, a nonprofit organization that aims to conduct ethical research with the Yanomami by seeking consent and addressing the wishes and needs of the community.
[...] Even if these ethical problems are ever solved, scientific ones will endure. For a start, while we believe that microbial diversity is important, we haven’t firmly established anything other than a correlation between health and a more diverse microbiome. Is this diversity responsible for a lack of chronic disease, or is it a consequence of a particular diet that might not even benefit everyone in the same way?
We know that antibiotics can disrupt our gut health. But the details of the link between microbial diversity and health are still largely a mystery. Even if you assume diversity is good, it’s not clear how much is needed—or what’s the best way to foster it.
Not too long ago, the line of thinking was that the more diverse your diet, the better. Now Allen-Vercoe isn’t so sure. People who live in big cities have such a wide range of food options that they can eat a different meal every day of the month. But they are thought to have some of the “least healthy” microbiomes, she says.
And for all we know, people in industrialized societies may have lost microbes because they no longer serve any purpose in our diet. Maybe they would be likely to cause an infection. Maybe doing away with some of them is really no great loss after all. Maybe the rise of chronic illness is only correlated with the loss of microbial diversity, and other factors are responsible.
Because microbes evolve and adapt to their environments, we should expect the microbiomes of people who live in cities to look different from those of people who live in forests. “There is no archetypal microbiome that everyone should [aspire to],” says Good. “Your microbiome is a reflection of your intimate interaction with your surrounding ecosystem, including the foliage, the air, the water, the food—and that all plays a role in driving the diversity of the microbiome within your gut and on your skin.”
(Score: 2) by Barenflimski on Monday December 25, @04:03PM
The 8 year old in me is giggling that in essence, these scientists are walking up to folks in the 3rd world and asking, "Can we have a bit of your poo?"
I suppose an easy way to get things dirtier would be to stop washing your hands. Handshakes anyone?