This section is from the "Health and Survival in the 21st Century" book, by Ross Horne.
When people talk about human evolution they usually assume it commenced only a few million years ago, starting from an ancestor in the form of some sort of ape. Others refer further back to the origin of the line of primates from which the apes evolved. But going even this far back reveals only changes in shape, size and brain capacity. Biologically and anatomically, the modern human is practically identical to these relatively immediate ancestors. So further and further back you can follow the evolutionary trail--granted with gaps here and there--and find that even earthworms have hearts, blood and immune systems of a rudimentary kind.
Did evolution start then with the first cell as many evolutionists suppose? How far back can we go? Well, if you really want to get involved, you can go back a long way further, because within every cell are contained living components and systems of greater complexity than ever, and research has shown that from the first appearance of life on Earth, it took several billion years for the aerobic cell itself to evolve, whereas all the rest since has taken but a billion years. In evolutionary terms the functioning cell was the breakthrough from which Nature could make trees and animals of all kinds. And finally (but hopefully not too finally) that dubious product, Homo sapiens . . .
What has all this talk of evolution got to do with germs and viruses? Viruses are the most primitive life forms known. By themselves they are inert and apparently lifeless, requiring combination with components within living cells before exhibiting lifelike characteristics. It is conjectured whether at one time they were part of the evolution of cells or whether they are unwanted remnants of the process. Viruses are of different sizes, the largest known being very much smaller than the smallest bacteria (germs), which are in fact simple cells. Some bacteria are aerobic (require oxygen) and some are anaerobic, depending on whether oxygen is available to them or not, being capable of change according to the state of their immediate environment.
All living things on Earth are interdependent on other living things, the entire scenario being in a rather fine balance. The upsetting of this balance even just a little may result in the extinction of some life forms and drastic changes in others struggling to survive. We are now getting closer to the point, which is: what part of the scheme of things do germs and viruses play?
All forms of life are capable, in varying degrees, of adapting to environmental changes, and germs and viruses have been doing that from time immemorial. They are part of the scenario of life, they have a role to fill and a purpose to serve as part of Nature's "Grand Design".
When Anton van Leeuwenhoek (1632-1723) constructed one of the first effective optical microscopes, he was astounded at the complexity of miniature life forms that inhabited the world unseen to the naked eye. In a drop of clear water were myriads of tiny microbes of different kinds moving about. Similar microbes are everywherein the air, the soil, the water and within living tissue. Van Lceuwenhoek said: "I have had several gentlewomen in my house who are keen on seeing the little eels in vinegar [nematodes], but some of them were so disgusted at the spectacle that they vowed they would never use vinegar again. But what if one should tell such people in future that there are more animals living in the scum on the teeth in a man's mouth, than there are men in the whole kingdom?"
Thus since before the higher forms of life began to appear, the world has been teeming with bacteria (germs), which micro-organisms form the basis of all other forms of life. They manufacture soil out of rock, destroy unhealthy tissues of plants and animals, break down dead tissues of plants and animals to be used again, and actually form an essential part of the body and body functions of all animals. In this latter regard the behavior of the various forms of bacteria normal in the body is dependent on the environment within the body (which should be healthy but very often in humans is not), and it is only when the milieu interieur becomes deteriorated that many normal bacteria change from a benign form to a pathological form, again as a natural consequence. In Nature it is the survival of the species that counts, and individuals are expendable for the survival of the majority. The weak or sickly in the wild are not tolerated to handicap the group, and one way or another are soon eliminated by predators appointed for the purpose. C'est la vie. So when a person allows a pathological condition of body chemistry to develop within them they should realize that what follows is not a perversity of fate or an unlucky encounter with germs of a criminal nature, but merely another step in a natural sequence of events.