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No. 125: Sep-Oct 1999

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Tyrannies Of The Tiny

Because we cannot see them with the naked eye, we tend to forget that the earth's atmosphere, its oceans, and the solid crust to unknown-but-great depths are colonized in profusion by minute biological entities -- mainly bacteria and viruses. Only when we get the flu or infected finger do these entities impinge upon our consciousness. Below we will learn that there are many more of them than you think.

Do viruses control the oceans? You may avoid the beaches after you learn that one teaspoon of seawater typically contains 10-100 million viruses and onetenth that many bacteria. Obviously, most are harmless to humans. However, the viruses do infect the bacteria and phytoplankton, destroying them, and thereby releasing their nutrients. By doing this, they keep the oceans' biological engines running. Further, the viruses act as genetic engineers as they transfer DNA from one individual to another. The oceans may be viewed as vast test tubes in which biodiversity is maintained by teeming, invasive viruses.

(Suttle, Curtis A.; "Do Viruses Control the Oceans?" Natural History, 108:48, February 1999.)

We are only 10% human! The average human body contains 100 trillion cells, but only 1 in 10 of these cells is your own. The remaining 90% are bacteria. These alien organisms coat your skin and pave your inner passageways from mouth to anus. Of course they are much smaller than your own cells, so what you see is mostly you. Even so, you are a composite creature and cannot survive without these tiny hitchhikers and symbionts.

Just as in the oceans, our bodies are battlegrounds. Each day we are thrice invaded by massive new armies of bacteria present our food. Water and air, too, bring more combatants into the fray. Our resident bacteria continually fend off the invaders or accommodate them. Some are pathogenic and must be killed; others are useful in many ways, as in digestion.

Who's really in charge in our bodies: the 90 trillion bacteria or the 10 trillion cells we call our own? Probably, neither!

(Hamilton, Garry; "Insider Trading," New Scientist, p. 42, June 26, 1999.)

Comment. We hear a lot about "selfish" genes and "selfish" DNA, and that we humans exist only to further the goals of DNA -- whatever they might be. But are not all these living bacteria and nonliving viruses also "selfish" at different levels of complexity? Humans may be at the top of the food chain, but are we really in charge?

From Science Frontiers #125, SEP-OCT 1999. � 1999-2000 William R. Corliss