By KIM BELLARD
You may have heard about the microbiome, that collection of microorganisms that fill the world around, and in, us. You may have had some digestive tract issues after a round of antibiotics wreaked havoc with your gut microbiome. You may have read about the rafts of research that are making it clearer that our health is directly impacted by what is going on with our microbiome. You may even take probiotics to try to encourage the health of your microbiome.
But you probably don’t realize how interconnected our microbiomes are.
Research published in Nature by Beghini, et. al., mapped microbiomes of almost 2,000 individuals in 18 scattered Honduras villages. “We found substantial evidence of microbiome sharing happening among people who are not family and who don’t live together, even after accounting for other factors like diet, water sources, and medications,” said co-lead author Francesco Beghini, a postdoctoral associate at the Yale Human Nature Lab. “In fact, microbiome sharing was the strongest predictor of people’s social relationships in the villages we studied, beyond characteristics like wealth, religion, or education.”
“Think of how different social niches form at a place like Yale,” said co-lead author Jackson Pullman. “You have friend groups centered on things like theater, or crew, or being physics majors. Our study indicates that the people composing these groups may be connected in ways we never previously thought, even through their microbiomes.”
“What’s so fascinating is that we’re so interconnected,” said Mr. Pullman. “Those connections go beyond the social level to the microbial level.”
Study senior author Nicholas Christakis, who directs the Human Nature Lab, explained that the research “reflects the ongoing pursuit of an idea we articulated in 2007, namely, that phenomena like obesity might spread not only by social contagion, but also by biological contagion, perhaps via the ordinary bacteria that inhabit human guts.” Other conditions, such as hypertension or depression, may also be spread by social transmission of the microbiome.
Professor Christakis thinks the findings are of broad importance, telling Science Alert: “We believe our findings are of generic relevance, not bound to the specific location we did this work, shedding light on how human social interactions shape the nature and impact of the microbes in our bodies.” But, he added: “The sharing of microbes per se is neither good nor bad, but the sharing of particular microbes in particular circumstances can indeed be good or bad.”
This research reminded me of 2015 research by Meadow, et. al., that suggested our microbiome doesn’t just exist in our gut, inside other parts our body, and on our skin, but that, in fact, we’re surrounded by a “personal microbial cloud.” Remember the Peanuts character Pigpen, who walked around in his personal dirt cloud? Well, that’s each of us, only instead of dirt we’re surrounded by our microbial cloud–and those clouds are easily discernable from each other.
Dr. Meadow told BBC at the time: “We expected that we would be able to detect the human microbiome in the air around a person, but we were surprised to find that we could identify most of the occupants just by sampling their microbial cloud.”
Those researchers predicted:
While indoors, we are constantly interacting with microbes other people have left behind on the chairs in which we sit, in dust we perturb, and on every surface we touch. These human-microbial interactions are in addition to the microbes our pets leave in our houses, those that blow off of tree leaves and soils, those in the food we eat and the water we drink. It is becoming increasingly clear that we have evolved with these complex microbial interactions, and that we may depend on them for our well-being (Rook, 2013). It is now apparent, given the results presented here, that the microbes we encounter include those actively emitted by other humans, including our families, coworkers, and perfect strangers.
Dr. Beghini and colleagues would agree, and further suggest that it’s not only indoors where we’re sharing microbes.
I would be remiss if I didn’t point out new research which found that our brains, far from being sterile, are host to a diverse microbiome and that impacts to it may lead to Alzheimer’s and other forms of dementia.
Could we catch Alzheimer’s from someone else’s personal microbiome cloud? It’s possible. Could we prevent or even cure it by careful curation of the brain (or gut) microbiome? Again, possible.
The truth is that, despite decades of understanding that we have a microbiome, we still have a very limited understanding of what a healthy microbiome is, what causes it to not be healthy, what problems arise for us when it isn’t healthy, or what we can do to bring it (and us) to more optimal health. We’re still struggling to understand where besides our gut it plays a crucial role.
We now know that we can “share” parts of our microbiome with those around us, but not quite what the mechanisms for that are–e.g., touch, sharing objects, or having our personal clouds intersect.
We feel like we are where scientists were two hundred years ago in the early stages of the germ theory of disease. They knew germs impacted health, they even could connect some specific germs with specific diseases, they even had rudimentary interventions based on it, but much remained to be discovered. That led to vaccines, antibiotics, and other pharmaceuticals, all of which gave us “modern medicine,” but failed to anticipate the importance of the microbiome on our health.
Similarly, we’re justifiably proud of the progress we’ve made in terms of understanding our genetic structure and its impacts on our health, but fall far short of recognizing the vastly larger genetic footprint of the microbiome with which we co-exist.
A few years ago I called for “quantum theory of health”–not literally, but incorporating and surpassing “modern medicine” in the way that quantum physics upended classical physics. That kind of revolution would recognize that there is no health for us without our microbiome, and that “our microbiome” includes some portion of the microbiomes of those around us. We talk about “personalized medicine,” but a quantum breakthrough for health would be treating each person as the symbiosis with our unique microbiome.
We won’t get to 22nd century medicine until we can assess the microbiome in which we exist and offer interventions to optimize it. I just hope we don’t have to wait until the 22nd century to achieve that.
Kim is a former emarketing exec at a major Blues plan, editor of the late & lamented Tincture.io, and now regular THCB contributor
