Biodiversity of Self: We Are More Than “Us”

by Galen Guerrero-Murphy on August 12, 2012

human torus microbiome

Did you ever consider the biodiversity inhabiting your own organism, your self? Your body is much more than just “you.” Well, what is “you” anyway?

Our bodies, and those of most animals, can be visualized as a torus (a donut, thank you Radiolab for this visualization). Out is in and in is out.

Our mouths are gates, but they are not closures to the outside. We take in the outside with every meal, kiss, and breath. And on the other end, our release of waste is evidence enough of our permeability. We are not closed systems.

We are superorganisms–biodiverse, seemingly single beings who are actually comprised of many, many different species. Much more than just Homo sapiens, we are biodiverse metacellular amalgamations of many organisms.

Thinking beyond the torus visual, there really is no “out.” Our skin creates an illusion of ourselves as discrete beings, but even these cell layers are somewhat permeable and crawling with tiny species. Sure, self is contained, but we are porous.

So what is within? Well, as it happens, the majority of “our” cells are bacteria. 100 trillion of them to be precise. This is 10 times the number of “our own” human cells. Among mammals, this includes 500 to 1,000 unique species comprising our “microbiomes,” including Bacteroides, Eubacteriales, Clostridium, Ruminococcus and Faecalibacterium. There’s also some fungi and archaea in the mix.

According to Scientific American:

The infestation begins at birth: Babies ingest mouthfuls of bacteria during birthing and pick up plenty more from their mother’s skin and milk.

What is now being realized is that many of these species are unique to our species and our individual bodies (see here and here and here). They have coevolved with us over millennia, resulting in beneficial, symbiotic relationships that are uniquely our own–they help us resist infection and diseases, digest and extract energy from our food, and synthesize vitamins; we provide them a comfortable home.

We have been loaded with microorganisms throughout our evolutionary history–it makes perfect sense that they would evolve along with us! Thus, just like our genetics, our microbial build-up is uniquely ours–other species (and other people) have different microbiomes.

Perhaps you enjoy yogurt, inhabited by billions of Lactobacillus acidofilus and others. Or maybe kombucha and the beloved SCOBAY (symbiotic culture of bacteria and yeast) it contains, comprised of a similarly diverse concoction for our gut. All the time we are introducing new lifeforms to our body to enhance the microbiome (…which may or may not be too effective)

Meanwhile, with a fear of bacteria we wash our hands and brush our teeth with antibacterial agents, prescribe (and flush…) large doses of antibiotics, and inhabit ultra-hygienic environments.

We imagine ourselves as distinct entities, a single species, some thing that can and should remain pure. This is an illusion. 

We are in fact many species–a fantastic orchestration of many lifeforms creating the bioresilience of self.

How is your microbiome today?

[EDIT 08/29/12: It turns out that there is mounting evidence that microbiome formation begins well before birth, within the previously-thought-to-be sterile amniotic environment of the womb! See Jimenez et al 2005, Jimenez et al 2008, DiGiulio et al 2008 and Francino et al 2012.

And here is a favorite, illuminating quote from Francino et al on the early dynamics of the microbiome:

…maternally inherited populations detected in the infant at one month had been lost by 11 months, suggesting that early colonizers can be easily replaced by externally acquired species. Such dynamics limit the potential for development of long-term coadaptations between specific bacterial and host genotypes. Rather, an intermittent pattern of interactions between different strains and human genotypes is likely to result in a diffuse process of coevolution among all interacting partners.

There’s still so much to learn about the human microbiome!]

Image by Galen Guerrero-Murphy

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Ajanobi Benjamin Chibuzo September 17, 2012 at 5:11 am

Symbiotic association of self and micro-bacterium is a fabrics of living and sustenance, well done for your research work

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Galen Guerrero-Murphy September 17, 2012 at 7:42 am

Yes, our interconnectedness with symbiots, both species inside and outside of our body and in beneficial (mutualistic) and adversarial (parasitic) coupling, is so much the essence of life, sustenance and sustainability.

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