But emerging evidence on the role of bacteria in human physiology brings the wonder and promise — and the hazards of misunderstanding them — up close and personal.
Because in a very real sense, bacteria are us.
In 2007, the National Institutes of Health began an ambitious program called the Human Microbiome Project, which aims to take a census of all the microorganisms that normally live in and on the human body. Most of these live in the digestive tract, but researchers have also discovered unique populations adapted to the inside of the elbow and the back of the knee. Even the left and right hands have their own distinct biota, and the microbiomes of men and women differ. The import of this distribution of microorganisms is unclear, but its existence reinforces the notion that humans should start thinking of themselves as ecosystems, rather than discrete individuals.
Furthermore, we may be less singularly sentient and animal than thought. As research has shown bacteria:
“Bacteria can distinguish “self” from “other,” and between their relatives and strangers; they can sense how big a space they’re in; they can move as a unit; they can produce a wide variety of signaling compounds, including at least one human neurotransmitter; they can also engage in numerous mutually beneficial relationships with their host’s cells. Even more impressive, some bacteria, such as Myxococcus xanthus, practice predation in packs, swarming as a group over prey microbes such as E. coli and dissolving their cell walls.”
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