Even when we are alone, are we ever truly alone? Dorion Sagan, the son of evolutionary theorist Lynn Margulis and famed astronomer and astrophysicist Carl Sagan, describes in a lecture and companion publication from 2011 how humans are not simply humans; we are, instead, a vast network of other living things working [mostly] symbiotically within our bodies. He asks the reader to imagine an alien descending upon the lecture hall, brandishing some kind of laser beam that can vaporize every human cell in the body. Upon pulling this trigger, the extraterrestrial visitor would not find the audience totally annihilated, but instead a collection of ghostly figures; these residues of the human body are composed of the bacteria, fungi, viruses, parasites, and other microorganisms that coat our skin, aid our digestive system, and interact with other systems. In this sense, we are never uniquely solitary – instead, every human body is composed of trillions of other bodies working within it. According to Sagan, even “most of the DNA of the estimated 100 quadrillion cells in our bodies is not ‘ours,’ but belongs to cohabiting bacteria.”

A greater understanding of the microbial components that exist in our bodies has contributed to recent advances in how we theorize the human body, and specifically how we care for the body in a medical sense. According to Harvard’s T.H. Chan School of Public Health, the human microbiome – the term used to describe this vast network of microbes functioning symbiotically within the human body – is “labeled a supporting organ because it plays so many key roles in promoting the smooth daily operations of the human body.” Humans’ microbiomes are as unique as their DNA, which plays a part in their formulation; a person is first exposed to microorganisms at delivery, through nursing, and continuing through infancy as influenced by the mother’s own microbiome. A healthy microbiome serves a variety of functions to keep the human body functioning correctly, including:

  • Stimulating the immune system
  • Synthesizing certain vitamins and amino acids, including B vitamins and vitamin K
  • Breaking down complex carbohydrates in the large intestine
  • Fermenting indigestible fibers to produce short chian fatty acids that play a role in muscle function as well as possibly prevent chronic diseases
  • Supporting healthy digestion overall
  • Protecting against infectious and or dangerous organisms that enter the body through contaminated foods or water
  • Stabilizing the flora of the gut, preventing overgrowth of harmful bacteria
  • Maintaining microbial balance in the skin, which can reduce conditions caused by the excess growth of bacteria (acne) , fungus (Pityrosporum folliculitis), or other microbes (rosacea)

The utility of the human microbiome, like an expansive universe, is still under scientific investigation to understand the breadth of its influence over human systems, and how we can best foster a healthy microbiome to treat illnesses and increase wellness.