If you have access to the latest issue of THE MAGAZINE OF FANTASY AND SCIENCE FICTION (July-August), be sure to read this issue’s Science article by Pat Murphy and Paul Doherty, “Aliens Inside You.” It discusses our relationship with the microbes that inhabit our bodies. Microorganisms living inside us outnumber our own cells ten to one. The average person’s intestinal bacteria alone weigh about three pounds in the aggregate. Fortunately, most of them are harmless or beneficial. It’s well known that taking antibiotics sometimes leads to yeast infection because the drug kills off the bacteria that protect against yeast. Recent research suggests that H. pylori, the bacterium that causes ulcers (but only in 15% of the people who harbor it), helps to keep the immune system healthy, guarding against conditions such as allergies and asthma. And there’s an intestinal bug called C. difficile that can attack people whose benign gut bacteria have been wiped out by antibiotics. An experimental cure has been devised that works on some patients—a fecal transplant. Yep, just what it says.
The value of intestinal bacteria reminds me of a novel by Brian Aldiss, THE DARK LIGHT YEARS, in which human space explorers meet aliens called the Utod, who resist all attempts to communicate and are therefore regarded as mere animals. Disgusting ones, at that, because they wallow in their own feces. Misguided human observers try to force the Utod captives to exist in sterile conditions, unaware that the aliens' health depends on the symbiotic creatures living in their excrement. Here’s a review of the novel:The Dark Light Years
Murphy and Doherty suggest we might think of the inhabitants of our personal interior ecosystem as our “secret pets.”
Margaret L. CarterCarter's Crypt