GermsGermsGerms

There is the frequent assertion that evolutionary biology is wrong because.... well, just because. Mostly because creationists don't like it, they invent a lot of absurd objections, one of them that there is a difference between a "scientific theory," and a "scientific law." Now this is an ignorant and silly thing to say, but it seems to be emotionally gratifying to creationists. In public debates, the pro-science advocate commonly replies that "Evoluiton is as well established as the "Theory" of gravity, or the Germ Theory of Disease."


Of the two, I think that the germ theory is a far better example, because "germ theory" is in fact weaker than evolution. Consider that "germs" are very far from the cause of all medical diseases. Plus, there are typically individuals with sub-clinical infections, and in cross-species transmissions, there are wild-type reservoirs. Even expanding the notion of "germs" to any infectious agent- nematodes, protozoa, yeast, fungal, bacterial, viral, or prions- there are still major and common diseases that are caused by totally different agents. Take for example environmental toxins. Arsenic in ground water, selenium in "loco weed," particulate carbon, or asbestos are all inorganic causes of serious, and common diseases. Traumatic injuries, malnutrition, and genetic accidents are leading causes of death today. Ironically, over eating is gaining in industrial nations as a cause of death. These events are exceeding the deaths caused by infection, although they may have been more evenly matched with infectious disease prior to the development of antibiotics.

We enfold all of these etiological factors in medical practice, and theory. The parallel to evolutionary theory is fine grained. Not all mutations are positive, not all negative mutations are eliminated. Even positive mutations are not necessarily spread through-out a population if they are beneficial. The pace of evolutionary change can be rapid like an epidemic, or very slow and environmentally conditioned like secondary hypertension, or trace-element poisoning. A particular mutation can be beneficial in one habitat to one sort of organism, and lethal in another. And, all of life on earth has been profoundly altered by shear accidents. Meteors smashing into the planet are not conditions that are adapted to, or predictable.

(Random thoughts waiting for the truck to get fixed).