The exact ratio of human cells in our bodies to cells of various bacteria, archaea, and fungus species living in and on us is still some matter of debate. But it is generally agreed that “they” outnumber “us”. Human adults average around 37 trillion body cells. The same body hosts perhaps 100 trillion bacterial cells.
We largely live in a symbiotic balance with our microbiome, our passengers providing us some protection, digestion, and other services. However, a few (such as C. difficile) are opportunistic and can overwhelm our defenses if we get sick.
Watercolor, ink, and gel pen on paper. 6”x6”.