Once we were thought to be the mirror of perfection, created in God’s image, made to rule the planet, separate and unequal from all the other critters. (I speak of the Judeo-Christian tradition, the one I know best.) This was before we discovered how hybridized we are, how interconnected, how evolutionary. Instead of created in some designer’s image — a wonderfully anthropomorphic thought, that — we are actually chimeras, jerry-rigged compositions of life.
10,000 or so species of bacteria live on and in our skin, mucus, eyes, and, most especially, our gut. Most of the time, this biota is good for us; in fact, it is essential; we would not be alive, we would not be “human,” without it, which I think deepens the definition of human. There more bacterial cells than human cells in each of us; indeed, well over 90% of the DNA in us is bacterial. Our 23,000 human chromosomes are absolutely dwarfed by our millions of bacterial chromosomes. Microorganisms, including archaea and fungi, make up from 1-3% of our body mass.
At a recent Secret Science Club meeting, microbiologist Martin Blaser of NYU gave a run-down of some of the current research into this microbiome. He slyly started by noting how we have radically changed the macrobiome of the earth, leading to tremendous disruption of the life system of the globe. You will not be surprised to learn that the disruption caused by indiscriminate use of antibiotics in the food chain and children is becoming more and more obvious.
Of course things are complicated: one particular gut bacteria, Helicobacter pylori, has been disappearing from us over nearly a century; its reduction and absence is associated with a decrease in stomach cancers, which is good; BUT its absence is also associated with an increase in esophageal cancers.
As part of the absurdity of our corporate controlled destiny, Blaser had a couple of slides about the American obsession with germs; an ad for antibacterial chewing gum and one for an antimicrobial stapler. A stapler? For all those cooties at work, I guess. And who doesn’t see people using those antibacterial soaps all the time, which do more harm than good. The rise in C-sections is also cutting down microbiome diversity, since a good spectrum of bacteria is transfered to a baby via vaginal birth.
Allergies and obesity have skyrocketed in just a few generations, and many like Blaser point to the radical restructuring of our inner flora as contributing factors.
But getting back to the chimera analogy. Our genome is chockfull of viral DNA, the results of millions of years of interactions with viruses. These fundamental entities of life on earth, which were originally thought of as not actually alive (some still contest the liveness of them, if not the liveliness), may yet hold the key to the old conundrum of how life could have come from not-life.
And something that never stops blowing my mind: within our cells, mitochondria, the little energy factories, seem to have come from bacteria that was absorbed into early cellular life forms. Yes, we are star dust, but we are also cell-stuff, bacteria, virus, and parasites.