Source: “The Ultimate Social Network,” Jennifer Ackerman, Scientific American, June 2012, pages 36-43.
Even after taking a shower, there are trillions of one-cell organisms on and in your body, over six pounds for a typical adult. And it is a good thing.
Bacterial cells outnumber human cells ten to one. Over the past ten years scientists have begun to understand where they come from and what they do. The human DNA has between twenty and twenty-five thousand genes. Microbes have over three million. This allows many variations. Some of these include genes that encode for beneficial compounds that the body cannot produce. Other bacteria train the body not to overreact to outside threats. And some microbes bring disease, decay and death.
In the womb the fetus is fairly sterile of bacteria, encountering the first while passive through the birth canal. The environment provides the rest, and no two people end up with the same cluster of bacteria (commensals, from the Latin for “sharing a table”, also called our microbiome). Even identical twins have differing commensals.
The inadvertent overuse of antibiotics and sterilization may destroy beneficial microbes. “Our individual fates, health and perhaps even our actions may have much more to do with the variation in the genes found in our microbiome than in our own genes.” Even beneficial microbes can cause us harm if they end up in the wrong place, in the blood for example.
Much more study, now in progress, will determine tests for the presence or absence of important microbes in various parts of the body, and what remedies will alter the microbome to help the patient cope with many health problems. “Teasing apart cause and effect can be difficult.”
It seems that the idea of a sterile environment is one to avoid. Everything in moderation, even cleanliness.