Understanding Gut Microbes

To give you some context, our gastrointestinal tract is home to an enormous number of microorganisms, primarily bacteria. In fact, we carry over two pounds of these tiny organisms in our gut—more than 100 trillion in total. This staggering number means we are more bacteria than human cells, which is quite a mind-boggling realization.

These microscopic entities wield considerable influence over both our physical and mental health. They form a connection with our brain, often referred to as the gut-brain axis, working closely with our central nervous system. Previously, I discussed how our appendix might serve as a reservoir for beneficial bacteria. The ongoing research continues to explore how these microbes communicate with our brain and affect our overall well-being.

For a long time, it was believed that diet played the primary role in shaping our gut microbiome. However, new insights suggest that many of these microorganisms were inherited from our ancestors, coevolving with us over generations.

Recent Discoveries in Microbiome Research

Taichi A. Suzuki, a postdoctoral researcher at the Max Planck Institute in Germany, recently released findings in Science that illuminate how some of the beneficial microbes in our gut were passed down through countless generations. This study highlights the evolution of our microbiomes alongside our early human ancestors, spanning hundreds to thousands of years.

The diversity of gut microbiomes varies significantly among individuals across different regions of the world. While we understand that diet contributes to this diversity, the exact reasons for these variations among similar species remain largely unclear.

To illustrate, just as people from different continents exhibit varying physical traits due to their unique ancestral paths, our microbiomes have undergone a similar evolutionary journey.

Suzuki elaborates on his findings, stating:

"Our recently published study found that not only did microbes diversify with their early modern human hosts as they traveled across the globe, they followed human evolution by restricting themselves to life in the gut."

This suggests that many gut microbes adapted to live exclusively within us, sacrificing their ability to survive outside our bodies.

The Study's Methodology

Suzuki and his team analyzed human genome and microbiome data sourced from diverse populations worldwide. They collected samples from individuals in Cameroon, North America, South Korea, the UK, and Western Europe, including data from mothers and their young children in Gabon, Germany, and Vietnam. Ultimately, they compiled data from 836 adults and 386 children.

Using this information, they constructed phylogenetic trees to trace the lineage of 59 commonly shared microbial species. Their analysis revealed varying degrees of correspondence between human and microbial trees, indicating some strains have been passed down through generations, while others appear to be more closely related to free-living bacteria found in the environment.

This study suggests that many gut microbes are easily shared within communities and passed down from mothers to their children, minimizing exposure to external factors. This was confirmed through comparisons of samples from mothers and their children, which showed the same microbial strains.

Implications of the Findings

Suzuki's research paves the way for further investigations into our gut microbiomes and their generational impact on health. These insights could also influence medical practices, especially as doctors are exploring probiotic transplants to treat malnutrition by utilizing gut microbiomes from community members.

Given the disruptions Covid-19 causes to our microbiomes, which can allow harmful bacteria to thrive, this research becomes even more critical. It makes one consider the importance of maintaining a healthy diet.

Rethinking Our Dietary Choices

After learning about the gut-brain connection, I became more mindful of what I consume. While I’m not perfect in my choices, I recognize the importance of fostering a healthy microbiome for both mental and physical health.

Suzuki's findings prompt an even deeper inquiry into how ancient microbial strains, which have coexisted with humans for millennia, might influence our well-being differently from non-ancestral microbes.

Could it be that those with a so-called "old soul" actually have gut microbes that carry ancient wisdom? It’s a whimsical thought, yet it sparks curiosity about the intricate relationship between our bodies and the microscopic world within us.

This article originally appeared in the author’s free newsletter, Curious Adventure. It has been revised and republished with permission on Medium.

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