As a human being living on Planet Earth, I sometimes ponder where my species fits in to the planet’s ecosystem. I know, it’s not really a normal thought, and it might be more entertaining to see what one of the Kardashians wore yesterday (Who? LOL) but as the author of The Symbiont Factor I really do think about such things. You see, from a physics point of view (yes, I was initially an engineering major before biology) this planet really only has one source of incoming energy to keep “the circle of life” going. That incoming source of energy is of course sunlight. Only photosynthetic organisms can convert sunlight into biomass that is usable by other life forms such as humans. Photosynthetic organisms are all some version of a plant, simple or complex. Yes, cyanobacteria and algaes, it could be argued, are not plants-but they have chlorophyll and they photosynthesize, so they could for this purpose be grouped as “plants” in a looser way of thinking.
Here’s where things get interesting, because the only organisms which can digest cellulose are bacteria. The only remaining photosynthetic organisms are cyanobacteria, which are bacteria. It is therefore accurate to say that the processing of all “incoming energy” beyond the plant is dependent on bacteria. Think about it for a moment-termites cannot digest wood fiber, being completely dependent on their microbiome (gut bacteria!) to digest it. The same thing can be said of any other organism on the planet which eats plant material! Cows, horses, rabbits-all depend on a complex gut microbiome to digest plant fiber. We humans also depend on our gut bacteria to digest plant fiber. Nothing can digest plants without the aid of bacteria.
Why is this important? The above discussion should point out that without bacteria there could not be much life beyond the plant world and cyanobacteria. Indeed, some researchers have stated the belief that cyanobacteria may have been the first organisms on the planet, with complex groups evolving into what we see as plants and algaes today. Our present life form would not exist if it were not for our symbiont bacteria. Symbiont organisms, as explained in The Symbiont Factor, have provided us with a fast acting rapid evolution capability that has aided our survival and permitted our continued development. These symbiont organisms guide the development of our brain, endocrine system, and immune system. Without a balanced microbiome we cannot develop normally. Our microbiome greatly enhances our ability to cope with famine, stress, or immune challenges without having to resort to inter-generational evolution. The microbiome has at least 100x the gene count as our human cells and can change the activation of those genes (and our own!) to help us adapt and survive.
When you consider the above discussion and realize that we are routinely destroying our internal microbiome as well as the planet’s microbiome, it should be food for thought that our present level of function at the top of the food chain may be more precarious that we believe. The delicate microbial balance that allows our brain and body to function at a high level is easily disturbed by poor nutrition (think McDonald’s) and high levels of antibiotics from both medicinal use and residues in meats, as well as other factors discussed in my book. Learning the importance of the microbiome is essential to understanding life itself!