In our understanding of evolution, we like to believe that humans are the end-all, be-all of a system that has slowly inched toward perfection for millions of years. We are the pinnacle of intelligence, independence, dominance, and control over ourselves and nature. From shapeless amoeba in a prehistoric sea to the internet-inventing humanoids who bested every living creature from neanderthal to sabretooth to microscopic viruses, we’re the alphas.
So how could trillions of microorganisms outnumber our cells by 10 to 1, making up nearly 3% of our body weight? How could microbial genes make up more than half of the human genome? How could our bodies contain enough living microbes to be considered an entire forgotten organ? How could it be true that without these microscopic bacteria and microbes, we would die within hours, if not minutes? What is a human being if our lives depend on trillions of organisms we cannot see or feel?
The gut microbiome is often described as an organ unto itself rather than a collection of bacteria, viruses, and non-pathogenic fungi. And microbes do not just live in our gut. They exist throughout our bodies. It has only recently been discovered that it is the lack of those microbes, not their presence, that often leads to disease and chronic illness. Our relationships with the trillions of tiny bugs in and on our bodies are the most intimate relationships we’ll ever have; they cannot exist without us, and we cannot live without them. We are only human because of our symbiotic relationship with bacteria, viruses, and fungi.
Your gut—and more broadly, your eyelashes, your mouth, and every inch of your skin—are a constant battlefield. Every minute of the day, microbes are working symbiotically, keeping you alive and maintaining an equilibrium between the good bugs and bad ones.
The broad category of “bacteria” can be broken into two categories: commensal and pathogenic. The commensal bacteria in our guts break down foods we cannot digest, regulate our immune systems and mental health (90% of serotonin receptors, the “feel good” hormone, reside in our gut), and produce vitamins that we cannot synthesize on our own.
The core of your microbiome is developed during gestation and at birth. What your mother ate, how you were born, and what you were fed as an infant are crucial to the composition of the microbes inhabiting your body. It is likely that one strain of bacteria once found in all humans, Bifidobacterium infantis, has gone completely extinct in nearly all human populations due to the use of antibiotics, along with the proliferation of c-section births and formula-feeding. However, the rest of your gut microbiome will shift throughout your lifetime based on what you eat, what medications you take, how active you are, where you live, and what chemical products you come into contact with daily.
The word “biotic” refers to living things, especially in an ecological sense. It follows then that the word “antibiotic” would refer to the opposite of that: anti-life. Overuse of antibiotics will not only cause bacterial resistance, but those bacteria-killing pills are indiscriminate in their work, annihilating both good and bad microbes in our bodies. Many physicians will prescribe probiotics to combat gastrointestinal issues (often originating from antibiotic use). Probiotics are the seeds of the gut microbiome. They are supposed to inoculate you with the strains of bacteria and fungi most often missing from your gut. However, their effectiveness is dubious. Prebiotics, on the other hand, are the food or fertilizer that those probiotics and microbes eat. Eating prebiotic foods can feed the bacteria already present in your gut, thereby increasing their population and effectiveness.
Akkermansia muciniphila. Bifidobacteria. Coprococcus. Lactobacillus. Prevotella. Roseburia. All these bacteria live inside of you, and all of them affect your day-to-day life. Each species and strain of bacteria or microbe functions differently in the body. Some of them, such as Akkermansia, help prevent inflammation by thickening the gut lining and producing many B vitamins in our body. _Corpococcus _helps regulate our moods; low levels are often found in the microbiome of people with depression. Roseburia works to deter pathogens through the creation of lactic acid bacteria. These microbes are nourished by different foods that we eat. Prevotella, for instance, helps regulate blood sugar and is abundant in the gut microbiome of hunter-gatherer tribes who consume hearty plant fibers. Lactobacillus, essential to balancing the pH of our gut, thrives on whole grains, grapes, apples, and berries.
Harmful bacteria can thrive in an environment with low acidity. Your gut is like a jar of pickles. It relies on good bacteria to produce lactic acid to keep the bad stuff out. That’s why fermented foods are chock-full of probiotics. Eating fermented foods like kimchi, sauerkraut, pickled fruits or vegetables, and fermented dairy, such as kefir or yogurt, is a delicious way to introduce natural and readily available microbes into your gut.
There is some speculation that pesticides and herbicides such as glyphosate may have the same effect on your gut bacteria that they do in the field, killing every microbe in sight. And it is possible that gluten sensitivity could, in part, be a reaction to the use of chemicals in wheat production that kill beneficial microbes and alter how wheat interacts with our bodies. It also appears that additives and binders in food, specifically those things on the ingredients list that you do not recognize and can barely pronounce, tend to disrupt gut microbiome activity by damaging good bacteria and feeding the bad. While many of those additives are derived the natural sources, our bodies are not used to digesting them in their singular and extracted form.
The advent of industrial farming has also killed much of the living soil that our food used to come from. A little dirt never hurt anybody, and in the case of the microbiome, the microbes from healthy soil are likely more beneficial than any probiotic pill you can buy. Microbes thrive on food with intact cell walls—essentially anything that has not been processed. The best way to get a dose of the soil microbiome into your diet is to grow or forage your own fruits, vegetables, and fungi.
People with pets and livestock tend to have a more robust microbiome and tend to get sick less frequently than those living in a sterile environment. Take that into consideration when gutting and skinning an animal you’ve hunted. In safe, small doses, contact with unique, wild microbes may increase the diversity of our gut microbiomes, increasing our resilience in the face of invading bacteria or viruses.
This view of the interaction between humans and microbes speaks to the new understanding of evolution as something that moves forward and sideways; a horizontal family tree in which genes are exchanged between organisms, and evolution occurs through cooperation rather than competition.
The next time you feel alone, remember that millions of tiny microbes are in and on your body, working to keep you alive. You are the evolutionary product of a galaxy’s worth of creatures living in symbiosis. All you need to do to keep yourself and your bugs healthy is to get outside, grow and gather food, ferment some of it, eat a wild animal now and then, and try not to wash off too much dirt.