Our ancestors lived in close contact with the environment

The microbiota in our environment influence the human intestine microbiome, via direct contact with soil and feces as well as via food (quality). Our ancestors lived in close contact with the environment (a, a cycle for pre-industrial microbiota). In contrast, human activities such as urbanization, industrialization of agriculture, and the modern lifestyle, including the use of pesticides and antibiotics as well as hormones (medication), together the loss of direct contact with soil and feces has depleted the richness of and overlapping with microbiota (b, a cycle for industrial microbiota). This depletion of microbial richness in all compartments can substantially affect human health.