Are bacteria culturally relevant? This was not the question put to me by Sputnik. Their question was, “What is the cultural relevance of bacteria?” This assumes that bacteria are culturally relevant. Bacteria? Culturally relevant? Huh?
Yeah, They Are! Or, More Than Your Average Sideshow
Actually, I think (although I had not considered the question before) the women of Sputnik are exactly right. I believe bacteria are culturally relevant, for a variety of reasons. First, when we examine how we have reacted to them, and how are views toward them have changed (or are changing) bacteria teach us something important about ourselves: how little we know how little we know, and how we overreact to the unknown, fearing it instead of learning about it.
In a sense, humanity’s learning of the existence of, initial negative attitude towards, and growing acceptance of bacteria provides a model for how we interact in general. Dutch fabric merchant turned microscope maker Antonie van Leeuwenhoek discovered bacteria. Before his groundbreaking microscope investigations in the 1600s—Leeuwenhoek was a little out of control—he looked not just at pond water but at the saliva of drunks and his own sperm in an attempt to unlock the secrets of this new world—the existence of a microscopic realm was not even suspected. At first microscopic life—and much of it, such at the protists, blood cells, rotifers, and nematodes Leeuwenhoek observed, are far bigger than bacteria—were considered something of drawing room oddity, a sideshow of Lilliputian lifeforms the meaning of whose existence wasn’t clear. (But then, was ours, really?)
Sick Creatures, More than Germs
But this was more the first cultural encounter with microbes than with bacteria. As these smallest of cells, bacteria, became recognized as ubiquitous in the environment, their special traits—and especially their role as causes of disease—came to the foreground. French chemist Louis Pasteur—whose name survives in the word pasteurization, the industrial process of killing bacteria by heating, for example, milk—showed that the widely believed theory of “spontaneous generation” was wrong. Spontaneous generation was the idea that life could arise spontaneously from the environment—for example decaying meat “turning into” maggots or, still more improbably, old rags morphing into rats. By curving and closing glassware, Pasteur prevented invisible-to-the-naked-eye floating bacterial and fungal spores from entering foods, preventing them from spoiling. This simple experiment showed that “spontaneous generation” was a nice idea but wrong—that bacteria were everywhere and they could get into stuff and grow, causing food to go bad for example. Still more important to the story of the original cultural reception of bacteria was the acceptance of the germ theory of disease. Very important, as it helped prevent many mysterious ailments that had before not been understood or, worse, attributed to the wrath of God. The most diabolical disease ever to harrow the minds and bodies of the Europeans—the black plague—was caused by a bacterium. A bacterium carried by rats and fleas but a bacterium: Yersinia pestis. Another scary killer, leprosy, was also laid at the feet of the bacterial bad guys. Not to mention tuberculosis—the deathly ailment of choice among the romantic beauties and deep souls of 19th century Europe. And of course syphillis, caused by the impolitic reproduction of a wriggling bacterium, the spirochete Treponema, at home in the human genital tract as it is in the hominid brain.
Needless to say, bacteria got a bad rap. As long as we paint them with too broad a brush: for bacteria are not all bad. As with prejudices against certain ethnic groups, our prejudice against them—“germs” we call them, as if the matter ended there—is based on first impressions and ignorance. Fortunately, this is changing. The trajectory of human knowledge goes from ignorance to recognition accompanied by fear of the unknown. There is a brief window where we become familiar and gain some knowledge, leading us to be less frightened. Finally, we may take for granted whatever we learned, forgetting about it—making it imperative that we keep on top of our knowledge, continuing to learn.
The Other Side of Fear
It turns out that bacteria’s potential for destruction is a drop in the bucket compared to their capacity for creation, transformation, survival and evolution. We live on a bacteria-infused planet with powers comparable to those of a superhero. As fast as a speeding neuron, more powerful than locomotive. This is true. Bacteria conduct signals via electrochemistry just as our brain does. Stronger, in a way, even than Superman, plate tectonics on Earth is partially a microbial phenomenon. Tiny skeleton-producing plankton in the sea fall to the ocean floor when they die. Their calcium carbonate accumulates, producing a lubricant for the spreading of tectonic plates. When the continental plates crash into each other, mountains appear. While not themselves bacteria, the marine microbes involved in mountain building had bacterial ancestors. Genetic evidence is quite clear on the once-controversial topic: the oxygen-using parts of our cells, the mitochondria, have free-living bacterial ancestors. So do the green parts of plant cells, the chloroplasts, and other-colored photosynthetic organelles in kelp and seaweed cells. Like the little marine microbes making shells that help make and move mountains, so the cells of our body come from bacteria that symbiotically merged. The original encounter of the different kinds of bacteria may have been precipitated by one infecting another but not killing it, or by one eating another and not fully digesting it. Bacteria don’t have immune systems to reject foreign beings. Eating without digesting and invading without killing happen all the time in the bacterial world, leading not only to infection but to transformation, and the acquisition of new powers. The ancestors of plant cells were not photosynthetic but received their solar power from the bacteria they ate but didn’t digest. The ancestors to animal cells were poisoned by oxgyen but, invaded by oxygen users that didn’t kill all of them, the ones that survived became powerful aerobes—able not only to detoxify reactive and potentially deadly oxygen gas, but to make energetic use of it. Long before humans, cyanobacteria—the green bacteria, that became trapped in ancestral plant cells—poisoned the planet. Taking the carbon from carbon dioxide in the atmosphere and hydrogen from dihydrogen oxide—water—they blew off oxygen gas as they spread. This very reactive gas spread, burning the tissues of surface organisms that could not get out of the way into the mud, or evolve tolerance. Long before the Industrial Revolution or the Information Age, trillions of bacterial modules, each with a separate set of genes were performing natural experiments in recombination, genetic engineering. They were metabolically evolving, and still show a much greater metabolic diversity—the basic instructions for growing in the cosmic environment—than all plants and animals combined. Bacteria live inside rocks and in geysers using inorganic chemical reactions, they can grow by fermentation and without oxygen, they can use light instead of food for energy, they can “breathe” arsenic, and on and on. Just one of their great inventions, the photosynthesis which produces oxygen as a “waste” and meanwhile grows food at room temperature with nanotechnological precision, would represent a tremendous breakthrough if it could be replicated in the laboratory. If we could only do what the “lowly” germs whom we were so quick culturally to peg—first as natural curiosities, and then as dreaded pathogens—if we were able to do technologically only a fraction of what they can do biologically, we would be able to produce green power plants, biodegradable plastic, rubber, and other materials, and designer foods without destroying the environment as we otherwise tend to. There is much more to be said about bacteria and you should check out my co-authored book, Microcosmos: Four Billion Years of Bacterial Evolution if you want to know more. But, in terms of the cultural relevance of bacteria, I think they are. Not just because of themselves, but because the example of humanity’s historical encounter with bacteria—which has led to disease prevention, pasteurization, characterization of the replicating antics of the DNA molecule, biotechnology, and a growing appreciation of the deep role they have played in evolution—is an object lesson in learning in general. We don’t know what we don’t know. Once we do encounter something new, our initial response is often fear. Nothing in life is to be feared, only understood, wrote Nobel laureate Marie Curie. And so it is: we must, to understand and continue to live in our world, move beyond fear to understanding. Whereas we once didn’t know of bacteria, and then feared bacteria as our mortal enemies, we must now recognize that we are in part bacteria. Some 10 per cent of the dry weight of our bodies comes from bacteria, and this doesn’t include the symbiotic groupies who “togethered” to make animal cells in the first place. Even today we cannot digest our food or produce vitamin B12 without gut bacteria. Yogurt with its lactic acid and other bacteria help us to remain healthy and free of the overgrowth of fungi, also natural hangers-on to the human body. If bacteria are the enemy we have met them and they are, to a surprisingly large extent, us. A fascinating recent example is the intracellular oxygen- and nitrogen-containing gas compounds that our bodies naturally deploy. This is a whole complicated aspect of the human immune system that was only discovered in the 1990s. Interestingly, those ancient oxygen-using bacteria that merged with anaerobic cells to become our mitochondria play a central part. Without plenty of functioning mitochondria, our immune system becomes significantly impaired. It is for this reason that some scientists suggest that the billions of dollars being spent on AIDs research—first set up before this discovery in the 1990s of the ancient bacteria-based immune system—is being wasted.
In the end the cultural relevance of bacteria can hardly be overestimated. Understanding them is a key not only to developing clean industry, solar energy, and biotechnology, but to sustainable ecology and the future of effective medicine. Bacteria, whose life style is so different than that of larger life forms like us that they would have been considered a new form of life if they were found on Mars or Venus rather than on Earth, are key to understanding who, what, and why we are on this crowded planet flowering forth new life forms for well over three billion years. They are not only pathogens but our ancestors, hardy organisms that survived multiple mass extinctions, coming back more diverse each time.
Perhaps the single most important lesson bacteria have to offer us culturally is what they say about the need to live and work together: merging bacteria, exchanging genes and living inside each other, becoming together the basic module for animals, plants, and all larger organisms, are radically diverse. Their principle is one of inclusion, incorporating more different and diverse types into ever more potent and sustainable metabolisms. We may fear the unknown but they seem to embrace it—literally!