Just me, myself and I?
You pride yourself on your individuality? Your looks, your tastes, your goals, your lifestyle, your relationships, and perhaps even your health and longevity?
Fairly normal if you are based in an urban setting with westernised values…
And yet, as self-defined and -determined as you like to perceive yourself, you are at heart a community. A highly distinctive community, yes, but a community, nonetheless.
What are we talking about? Your microbiome, of course. And not just the one that sits in your gut, but the one that colonises your entire digestive tract – beginning in your mouth. Not to mention the communities nestled all over your skin, in your nose and lungs, in your ears and around your eyes as well as in and around your urogenital organs.
Feeling slightly dizzy or downright disgusted? Just wait till you hear more of the hard facts…
Your very own jungle!
So, who or what exactly is populating you? Your microbiome is primarily comprised of bacteria, fungi, archaea, protists and viruses. But it’s not just a few dozen that you may have caught, sprinkled here and there – be it on the doorknob, while shaking hands, sharing a telephone or… a toilet. No, the numbers are sheerly staggering. Indeed, you host between 10 and 100 trillion microbial cells.
In fact, the bacteria living on and in your body outnumber your own cells by a factor of 1.3 with a total mass of about 1-3% of your body. Hence, if you weigh e.g., 60 kg, this amounts to between 0.6 and 1.8 kg of “alien life” colonising you! And that’s leaving the smaller populations of archae, viruses and fungi out of the equation…
If you’re still unimpressed, wait till you hear what this represents in DNA terms!
Unique variety?
Fascinatingly, it appears that our microbiomes actually hold one of the most significant keys to our “individualities” – more so than our personal genetic profiles. Indeed, if you just narrow your perspective down to the human gut microbiome, it contains “a gene catalog of 3.3 million non-redundant genes as compared to the ∼22,000 genes present in the entire human genome”. So, our jungle metaphor may not be that far-fetched! What this concretely implies is that: “individual humans are about 99.9% identical to one another in terms of their host genome, but can be 80-90% different from one another in terms of the microbiome of their hand or gut.” (Ursell & al. 2012).
Moreover, a team around Harvard researcher Michael Snyder found out that the microbiome is not only as unique to an individual as a fingerprint, but its individuality also persists over time, and it modulates our health:
“A lot of people would suspect that the bacteria shared among us would be the most important and thus the most stable,” Snyder said. “We found the complete opposite — the personal microbiome is the most stable. It further suggests that our personal microbiome, different from everyone else’s personal microbiome, is pretty integral to our health. This makes sense because all have different healthy baselines.” (Williams, 2024)
So, you’re not just teeming with non-human life, this non-human life is so incredibly abundant and differentiated that it may even outshine your human individuality and “remote”-control your health. Ouch…
Biological steering wheels
But biochemist Hamid Zand pertinently reminds us that our human (mammal) uniqueness is the fruit of the complex interplay of at least three “information systems” as they interact with distinct environments (Zand 2024). First comes the (epi-)genome, then the central nervous system or so-called brain “connectome” and finally, the microbiome as the most influential modulators of our individualities – be they physical, mental or emotional.
Hence, the microbiome, as just one of the crucial factors, may not have the upper hand in defining who we are and how we (can) act. But by distinguishing these overlapping systems, concepts such as “individuality”, “free will” and “personal agency” become rather fuzzy and may indeed appear tenuous. Especially when you realise that you have very little conscious control over the three “-omes” … Who is “I” anyway?
From alienation to empowerment
Now you’re beginning to see why we playfully alluded to French poet Arthur Rimbaud [1854-1891] in our title. When he famously stated “I is another” [je est un autre], he alluded to the necessity for poets to sensorily and emotionally internalise as many human perspectives as possible, in order to convincingly distil them into their work. However, Rimbaud could not yet foresee the multitude of perspectives already embodied in our individual biologies.
Are *you* now feeling overwhelmed by all these internal and external control layers that seem to threaten your individuality and autonomy?
Despair not! You needn’t feel completely alienated and disempowered – even if biological fate seems to have let you down on all three of the “-ome” fronts. And even if bad habits and/or experiences seem to have left an indelible mark on your health and your sense of self…
Indeed, contemporary medicine has been discovering strategies to tweak these information systems. Medical disciplines, such as microbiology, biochemistry, neurology and psychiatry, not to mention immunology and (epi)genetics, are all working towards fostering better systemic cooperation to improve your health and quality of life. And the microbiome is a case in point – even if research is still in its infancy when it comes to fully apprehending and regulating it.
But let’s not put the cart before the horses! Our next instalment will first attempt to unveil where our individual microbiomes come from, how they evolve and some of manifold ways in which they influence our lives…
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Sources and further reading
(last accessed 16.10.2024)
“10 Facts about your microbiome”, MyMicrobiome, Online: https://www.mymicrobiome.info/en/10-facts-about-the-microbiome
Looi, Mun-Keat, “The human microbiome: Everything you need to know about the 39 trillion microbes that call our bodies home”, BBC Science Focus, July 14, 2020. Online: https://www.sciencefocus.com/the-human-body/human-microbiome
Reynoso-García Jelissa , Miranda-Santiago Angel E. , Meléndez-Vázquez Natalie M. , Acosta-Pagán Kimil , Sánchez-Rosado Mitchell, Díaz-Rivera Jennifer , Rosado-Quiñones Angélica M. , Acevedo-Márquez Luis ,Cruz-Roldán Lorna , Tosado-Rodríguez Eduardo L., Figueroa-Gispert María Del Mar, Godoy-Vitorino Filipa. “A complete guide to human microbiomes: Body niches,transmission, development, dysbiosis, and restoration”. Frontiers in Systems Biology, 2:2022. doi 10.3389/fsysb.2022.951403. Online: https://www.frontiersin.org/journals/systems-biology/articles/10.3389/fsysb.2022.951403/full
Gilbert JA, Blaser MJ, Caporaso JG, Jansson JK, Lynch SV, Knight R. "Current understanding of the human microbiome". NatMed. 2018 Apr 10;24(4):392-400. doi: 10.1038/nm.4517. Online: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7043356/
Sender R, Fuchs S, Milo R. “Are We Really Vastly Outnumbered? Revisiting the Ratio of Bacterial to Host Cells in Humans”. Cell. 2016 Jan 28;164(3):337-40. doi: 10.1016/j.cell.2016.01.013. Online: https://www.cell.com/cell/fulltext/S0092-8674(16)00053-2?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0092867416000532%3Fshowall%3Dtrue
“Bacteria Versus Body Cells”, Beyond Science, eppendorf, January 10, 2022. Online: https://www.eppendorf.com/de-de/beyond-science/health-medicine/bacteria-versus-body-cells-a-11-tie/
Ursell LK, Metcalf JL, Parfrey LW, Knight R. "Defining the human microbiome". Nutr Rev. 2012 Aug;70 Suppl 1(Suppl 1):S38-44. doi: 10.1111/j.1753-4887.2012.00493.x. Online: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3426293/
Williams, Sarah C.P. „Our bacteria are more personal than we thought, Stanford Medicine-led study shows”. Stanford Medicine News Center. March 12, 2024. Online: https://med.stanford.edu/news/all-news/2024/03/personal-microbiome.html
Zand, Hamid, “The Role of the Microbiome in What Makes Us Unique. How much of us is determined by our microbiome?”. Psychology Today. September 12, 2024. Online: https://www.psychologytoday.com/intl/blog/the-behavioral-microbiome/202409/the-role-of-the-microbiome-in-what-makes-us-unique
« Je est un autre – Domaine Public. Extrait de la lettre d’Arthur Rimbaud à Paul Demuny le 15 mai 1871 ». De Plume en Plume. Online: https://www.de-plume-en-plume.fr/histoire/je-est-un-autre-extrait-lettre-du-voyant
Illustrations
golubovy / iStock & epiAge
Max Ravier / pexels
Pixabay /pexels
g-stockstudio / iStock
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