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Looking after the multitudes of bacteria, fungi and other microorganisms living in our guts could help us think better and even offer new ways of treating mental health conditions. Your gut is a bustling and thriving alien colony. They number in their trillions and include thousands of different species.
Many of these microorganisms, including bacteria, archaea and eukarya, were here long before humans, have evolved alongside us and now outnumber our own cells many times over. Indeed, as John Cryan, a professor of anatomy and neuroscience at University College Cork, rather strikingly put it in a TEDx talk: “When you go to the bathroom and shed some of these microbes, just think: you are becoming more human.”
Collectively, these microbial legions are known as the “microbiota” – and they play a well-established role in maintaining our physical health, from digestion and metabolism to immunity. They also produce vital compounds the human body is incapable of manufacturing on its own.
But what if they also had a hotline to our minds? In our new book, Are You Thinking Clearly? 29 Reasons You Aren’t And What To Do About It, we explore the dozens of internal and external factors that affect and manipulate the way we think, from genetics, personality and bias to technology, advertising and language. And it turns out the microbes that call our bodies their home can have a surprising amount of control over our brains.
Over the last few decades, researchers have started to uncover curious, compelling – and sometimes controversial – evidence to suggest that the gut microbiota doesn’t just help to keep our brains in prime working order by helping to free up nutrients for it from our food, but may also help to shape our very thoughts and behaviour. Their findings may even potentially bolster how we understand and lead to new treatments for a range of mental health conditions, from depression and anxiety to schizophrenia.
The picture is still very far from complete, but in the wake of the Covid-19 pandemic, which has had a deleterious impact on people’s mental health in many parts of the world, unpicking this puzzle could be more important than ever.
One of the research field’s key origin stories took place in the North American wilderness – and, be warned, it makes for some stomach-churning reading. The year was 1822 and a young trader named Alexis St Martin was loitering outside a trading post on what is now called Mackinac Island, in what is now Michigan, when a musket accidentally went off next to him, firing a shot into his side from less than a yard (91cm) away.
His injuries were so bad that part of his lungs, part of his stomach and a good portion of his breakfast that day spilled out through the wound in his left side. Death seemed certain, but an army surgeon named William Beaumont rode to the rescue and saved St Martin’s life, although it took the best part of a year and multiple rounds of surgery.
What Beaumont couldn’t repair, however, was the hole in his patient’s stomach. This persistent fistula would remain a grim and lasting legacy of the accident, but Beaumont wasn’t one to pass up a good opportunity – however unpleasant. Realising that the hole provided a unique window into the human gut, he spent years investigating the intricacies of St Martin’s digestion.
Exactly how willing a volunteer St Martin was is open to debate as Beaumont employed him as a servant while conducting research on him – the murky arrangement almost certainly wouldn’t be considered ethical today. Among the findings Beaumont uncovered during his studies of St Martin’s guts, however, included how they were affected by its owner’s emotions, such as anger.
Through this finding, Beaumont, who would go on to be lauded as the “father of gastric physiology“, had hit upon the idea of a “gut-brain axis” – that the gut and the brain aren’t entirely independent of one another but instead interact, with one influencing the other and vice versa. And now we know that the microorganisms within our gut make this process even more complex and remarkable.
“More and more research is revealing that the gut microbiome can influence the brain and behaviour across a variety of different animals,” says Elaine Hsiao, associate professor in integrative biology and physiology, at the University of California, Los Angeles (UCLA).
It’s important to remember that the microbes were here before humans existed, so we have evolved with these ‘friends with benefits’ – John Cryan
How exactly our microbiota might be influencing our mind is a growing, pioneering and still relatively novel field. But there have been advances over the last 20 years or so, particularly in animals. And, slowly, a case is being built to suggest that these microorganisms aren’t just a vital part of our physical selves, but also our mental and emotional selves, too.
“In medicine, we tend to compartmentalise the body,” says Cryan. “So, when we talk about issues with the brain, we tend to think about the neck upwards. But we need to frame things evolutionarily. It’s important to remember that the microbes were here before humans existed, so we have evolved with these ‘friends with benefits’. There has never been a time when the brain existed without the signals coming from the microbes.
By Miriam Frankel and Matt Warren
Source: How gut bacteria are controlling your brain – BBC Future
31. Ancient Life: Apex Chert Microfossils”. http://www.lpi.usra.edu. Retrieved 12 March 2022.McCutcheon, JP (6 October 2021).
“The Genomics and Cell Biology of Host-Beneficial Intracellular Infections”. Annual Review of Cell and Developmental Biology. 37 (1): 115–142. doi:10.1146/annurev-cellbio-120219-024122. ISSN 1081-0706. PMID 34242059. S2CID 235786110. Archived from the original on 7 July 2022. Retrieved 19 August 2022.oese CR, Kandler O, Wheelis ML (June 1990). “
Towards a natural system of organisms: proposal for the domains Archaea, Bacteria, and Eucarya”. Proceedings of the National Academy of Sciences of the United States of America. 87 (12): 4576–79. Bibcode:1990PNAS…87.4576W. doi:10.1073/pnas.87.12.4576. PMC 54159. PMID 2112744.Godoy-Vitorino F (July 2019).
“Human microbial ecology and the rising new medicine”. Annals of Translational Medicine. 7 (14): 342. doi:10.21037/atm.2019.06.56. PMC 6694241. PMID 31475212.Schopf JW (July 1994).
“Disparate rates, differing fates: tempo and mode of evolution changed from the Precambrian to the Phanerozoic”. Proceedings of the National Academy of Sciences of the United States of America. 91 (15): 6735–42. Bibcode:1994PNAS…91.6735S. doi:10.1073/pnas.91.15.6735. PMC 44277. PMID 8041691.Brown JR, Doolittle WF (December 1997).
“Archaea and the prokaryote-to-eukaryote transition”. Microbiology and Molecular Biology Reviews. 61 (4): 456–502. doi:10.1128/mmbr.61.4.456-502.1997. PMC 232621. PMID 9409149.Battistuzzi FU, Feijao A, Hedges SB (November 2004). “
A genomic timescale of prokaryote evolution: insights into the origin of methanogenesis, phototrophy, and the colonization of land”. BMC Evolutionary Biology. 4: 44. doi:10.1186/1471-2148-4-44. PMC 533871. PMID 15535883.Homann, Martin; et al. (23 July 2018). “
Microbial life and biogeochemical cycling on land 3,220 million years ago” (PDF). Nature Geoscience. 11 (9): 665–671. Bibcode:2018NatGe..11..665H. doi:10.1038/s41561-018-0190-9. S2CID 134935568.Gabaldón, T (8 October 2021). “
Origin and Early Evolution of the Eukaryotic Cell”. Annual Review of Microbiology. 75 (1): 631–647. doi:10.1146/annurev-micro-090817-062213. ISSN 0066-4227. PMID 34343017. S2CID 236916203. Archived from the original on 19 August 2022. Retrieved 19 August 2022.Callier, Viviane (8 June 2022). “
Mitochondria and the origin of eukaryotes”. Knowable Magazine. doi:10.1146/knowable-060822-2. Retrieved 19 August 2022.Stephens TG, Gabr A, Calatrava V, Grossman AR, Bhattacharya D (May 2021). “
Why is primary endosymbiosis so rare?”. The New Phytologist. 231 (5): 1693–1699. doi:10.1111/nph.17478. PMC 8711089. PMID 34018613.“
Extremophilic Microorganisms for the Treatment of Toxic Pollutants in the Environment”. Molecules. 25 (21): 4916. doi:10.3390/molecules25214916. PMC 7660605. PMID 33114255.
“The biomass distribution on Earth”. Proceedings of the National Academy of Sciences of the United States of America. 115 (25): 6506–11. Bibcode:2018PNAS..115.6506B. doi:10.1073/pnas.1711842115. PMC 6016768. PMID 29784790.Kushkevych I, Procházka J, Gajdács M, Rittmann SK, Vítězová M (June 2021). “
Molecular Physiology of Anaerobic Phototrophic Purple and Green Sulfur Bacteria”. International Journal of Molecular Sciences. 22 (12): 6398. doi:10.3390/ijms22126398. PMC 8232776. PMID 34203823.
“A centimeter-long bacterium with DNA compartmentalized in membrane-bound organelles”. bioRxiv (preprint). doi:10.1101/2022.02.16.480423. S2CID 246975579..
“Mycoplasma hominis: growth, reproduction, and isolation of small viable cells”. Journal of Bacteriology. 124 (2): 1007–1018. doi:10.1128/JB.124.2.1007-1018.1975. PMC 235991. PMID 1102522.Velimirov B (2001). “
Nanobacteria, Ultramicrobacteria and Starvation Forms: A Search for the Smallest Metabolizing Bacterium”. Microbes and Environments. 16 (2): 67–77. doi:10.1264/jsme2.2001.67.Yang DC, Blair KM, Salama NR (March 2016). “
Staying in Shape: the Impact of Cell Shape on Bacterial Survival in Diverse Environments”. Microbiology and Molecular Biology Reviews. 80 (1): 187–203. doi:10.1128/MMBR.00031-15. PMC 4771367. PMID 26864431.Claessen D, Rozen DE, Kuipers OP, Søgaard-Andersen L, van Wezel GP (February 2014). “
Bacterial solutions to multicellularity: a tale of biofilms, filaments and fruiting bodies”. Nature Reviews. Microbiology. 12 (2): 115–24.
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