Microbiota and microbiome… a question of genes

It was the year 2000 and the scientific world was in a state of excitement over the final phase of the Human Genome Project, thanks to which the DNA sequence would be divided into its functional parts: the genes.

How many genes are needed to form a human being? This was the question that everyone was eagerly awaiting an answer to.

Considering the complexity of the human being, it was to be expected that this number would be particularly high, certainly much higher than that of a mouse which has around 23,000 genes, or of wheat with its 26,000 or even of a worm with 20,500 genes.

Some rumors spoke of 55,000 or even 150,000 genes, hypotheses that are absolutely plausible considering the innumerable human capabilities, compared to other forms of life.

And yet the long-awaited conclusion of the study was rather disappointing: 21,000 genes, little more than the genetic makeup of a worm.

The Human Genome Project was considered the key to understanding the complexity of the human being, but the contribution of that important study after many years has not fully met expectations. However, what was possible thanks to those studies, which are still considered a scientific achievement, was the creation of another important scientific project: The Human Microbiome Project – human microbiome project, the logical continuation of the Human Genome Project.

This project has not received the same media attention and the financial allocations have also been much lower, but despite this, the first results of these studies have already been astonishing.

The 21,000 genes that make up the human genome are not the only genes in our body, we do not live alone, a much more impressive number of microorganisms that we host make us a true SUPERORGANISM. We are talking about 100 trillion microbes, better known as MICROBIOTA which include bacteria, viruses, fungi and archaea. All together these microbes that live in the human body contain 4.4 million genes – 21,000 vs 4,400,000! These genes are our MICROBIOME, the collective genome of the MICROBIOTA.

Doing the math, one wonders whether our concept of “human being” today needs to open up to new awarenesses.

The studies on the human genome that were supposed to reveal “the language of God” as announced by Bill Clinton in those years, actually led us and are leading us to reveal what it really means to be human. But from another point of view.

Our evolution is closely linked to the existence of microbes and bacteria, these microorganisms were at our side even before we became "human". The more cells that make up an organism, the more microbes live in it. Coexistence and cooperation with microbes is fundamental in every evolutionary process and it was a billion years ago when the first living beings began to evolve.

But who are these microbes and what do they do for us? Do they “scrounge” a ride or do they offer an important service to our well-being and health in exchange?

The Human Microbiome Project, run by the National Institutes for Health in the United States, along with many other studies in laboratories around the world (including Italian ones) has revealed that our health and happiness are completely dependent on our symbiotic microbes.

Our body represents a real ecosystem that hosts different communities of microbes, it is colonized by them, but our microbes are unique, like our fingerprints.

This perception of the microbial side of ourselves is giving us a new vision of individuality. A new sense of connection to the microbial world. A sense of the legacy of our personal interactions with family and environment early in life makes us pause and consider whether there may be another dimension to our human evolution.

Jeffrey Gordon, biologist, Director of the Center for Genome Sciences and Systems Biology at Washington University in St. Louis. Member of the National Academy of Sciences, the American Academy of Arts and Sciences, the Institute of Medicine of the National Academies, and the American Philosophical Society.

Recognizing the value of our symbiotic bacteria is the first step towards a new frontier, towards a new awareness of the real meaning of being “human” that puts us in another perspective, different from the highest point of the podium from which we are used to considering everything that surrounds us. It means that we are not as we think we are and that our health and happiness also depend on the ability we have to take care of that 90% of us that we are not used to considering part of us but that represents a part, not only frighteningly large, but also fundamental.

How? In the meantime, starting with the little bit of us that remains wouldn't be bad! Our health and well-being depend largely on the choices we make: the foods we eat, the medications we take, the lifestyle we lead determine the quality of our life and also that of our population of microbes. Our superorganism is programmed to function well if we make the right choices, if we don't hinder that balance. Welcoming our microbes with awareness and gratitude, recognizing them as a fundamental part of us, knowing which habits to adopt to best nourish our microbial colony, the microbiota, that internal garden that makes our life more beautiful, is essential to have a real awareness of who we are and to observe ourselves or consider ourselves in our entirety, 100% human but in happy company, in peace, harmony and balance with the bacteria that travel with us during our existence and that contribute to creating the best part of us.

Because the more happy bacteria there are, the more happy and healthy humans will populate the Earth. And perhaps it will be the beginning of a new Era.

Bibliography

International Human Genome Sequencing Consortium, “Finishing the euchromatic sequence of the human genome” Nature 431: 931-945 (2004)

The Human Microbiome Project Consortium, “Structure, function and diversity of the healthy human microbiome” Nature 486: 207-214 (2012)

“Role of microorganism in the evolution of animals and plants: the hologenome theory of evolution” FEMS Microbiology Reviews 32: 723-735 (2008)

Zilber-Rosenberg, I. and Rosenberg E. “Diet rapidly and reproducibly alters the human gut microbiome” Nature 505: 559-563 (2014)

David, L.A. et al. “Impact of diet in shaping gut microbiota revealed by a comparative study in children from Europe and rural Africa”, Proceedings of The National Academy of Science 107 (2010): 14691-14696, De Filippo, C. et al.

Reading tips

“The Happiness Bacteria” Alanna Collen

“ The Human Superorganism: How the Microbiome Is Revolutionizing the Pursuit of a Healthy Life” Rodney R. Dietert Phd

“I Contain Multitudes: The Microbes Within Us and a Greater View of Life” Ed Yong