More than 30 trillion microorganisms—roughly as many as the number of cells in our own bodies—inhabit each of us. Without them, we—and indeed all animals and plants—would not be able to survive. We call the entire, highly active community of bacteria, fungi, algae, and other microorganisms—as well as viruses—on and inside our bodies, on plants, in food, or in other places where they interact with one another the “microbiome.” [40]
This “primordial community of all diversity” organizes the exchange of nutrients and biological information both within a single organism and between organisms. Microbiomes build up and break down, digest and process, and have thus formed the basis of all life for billions of years. Their “home” is the soil, where everything that lives in the countryside—and eventually decays—comes together.
Humans have been purposefully interacting with these organisms since the dawn of time—for example, in medicine, food production, and the promotion of soil fertility. Nevertheless, research into them is still in its very infancy. One thing seems certain so far: it is the diversity of the microbiomes that ensures a healthy balance and effective interaction.
Since the Industrial Revolution, the microbiome has been shaped by many new factors. At the same time, we have lost contact with the soil, plants, and even feces, resulting in a drastic reduction in the biodiversity of the human microbiome today. [41]
