Charles Darwin developed the Theory of Evolution, but neither he nor co-discoverer Alfred Russel Wallace coined the word. "Evolution" as a biological term was in use as far back as the time of Darwin's famous grandfather, poet-physician-naturalist-inventor Erasmus Darwin.

Sometimes I think it would have been better if no one had ever used the term at all. "All living things modify themselves over time in response to changes in their surroundings, and over very long times the modifications become so large that the new organism is vastly different from the old."

Phrased that way, I believe that most of the battles over the truth or falseness of evolution never would have been fought.

I'm not going to argue either for or against the ideas, because you can find those debates in a thousand places. They began in 1859, with the publication of Darwin's "The Origin of Species," and they continue to this day, recently and famously when the Kansas Board of Education declared that evolution was not a fit subject for the state's required science curriculum.

My target is something that sounds related but really isn't, a subject perhaps even more controversial. When people argue about evolution, they often mix together two completely different subjects: One, how did today's great variety of living creatures arise? Two, how did life itself, in any form at all, appear on earth?

Most biologists are convinced that they can answer the first question in fair detail, by applying the ideas of evolution, while admitting near-total ignorance when it comes to the second. Given one living, self-reproducing organism, we can see ways over time to produce all others; but how the devil did that first living critter come into existence? Are there any answers, other than divine intervention?

This is not a column about religion, but even the most agnostic of scientists will admit that today's theories about the origin of life all have problems; to believe in any of them calls for a high degree of faith.

Here's why. Even the "simplest" self-sustaining organism goes through a complicated procedure in order to build and reproduce itself. The basic information that defines the creature is its genetic code, stored as sequences of DNA molecules. The DNA sequence is copied onto a sister form of molecule, called RNA. The RNA is transferred inside the living cell to a "protein factory" known as a ribosome. The ribosome uses the blueprint provided by the RNA to make all the proteins and other materials necessary for an organism to grow and thrive, and, ultimately, to reproduce itself by making copies of its own DNA.

This is a pared-down description of a complicated process, but it makes one point perfectly clear: in order to define an organism, the DNA molecules must exist; in order to build an organism, the protein-factory ribosomes also must exist. If you don't have both of these, you won't have a self-sustaining and self-reproducing living creature.

Here, then, is the problem. For life to exist and prosper, three quite separate developments must have taken place: the use of DNA for information storage, the use of RNA to carry information to the ribosome protein factories, and the development of the ribosomes themselves where the proteins are made. One of these might have developed by chance and favorable circumstances. But all three - and simultaneously? The odds against go from unfavorable to astronomical. And yet you are reading this column, certain proof that life exists.

Popular current thinking is that DNA was a latecomer, and that everything began with RNA. RNA is a very close relative of DNA, with just one molecule, uracil, replacing the thymine molecule of DNA. It carries the basic genetic information for certain viruses. More important, RNA can in certain circumstances copy itself, it can create proteins, and it can modify its own form. The very first self-reproducing organism may have been a fragment of RNA, floating in the ancient seas of earth. Later, DNA developed from RNA, and in four billion years the descendants of that original RNA fragment have grown and diversified to become every living thing on the planet.

Now for the million-dollar question: Do I believe it? Did life really begin this way?

I must admit, the suggested process leaves me uneasy and somewhat unpersuaded. But other proposed answers - such as that life first developed as crystalline forms in clays - appeal to me even less.

So how did life arise on earth? I'm sorry to say that the best answer today is that old and trusted standby: Nobody knows.

"Borderlands of Science" is syndicated by: