November 16, 1989
As I was sitting in my chair,
I knew the bottom wasn't there;
Nor legs nor back, but I just sat,
Ignoring little things like that.
Hughes Mearns (The Perfect Reactionary/
The fact that evolution has occurred and is occurring is accepted by virtually all biologists. I say virtually because, just as you can find a few people who believe that the earth is flat, you could probably find a biologist who doesn't accept the fact of evolution. While it is a fact, it is still referred to as the Theory of Evolution.
Why do scientists use the word theory, rather than law? Since we have no way of actually looking into the past, the best that we can do is draw conclusions from the available evidence; which is considerable. Precisely how evolution occurred is, therefore, still theoretical; and is likely to remain so. Darwin and Wallace thought that it occurred by the process called Natural Selection. There are scads of observations and experiments which have amply proved that natural selection does occur and is immensely important in evolution. Whether it can explain ALL of evolution is open to question. Natural selection, as the term is used today, assumes that evolution occurs by means of small genetic changes (mutations). Critters with the new gene can do better or worse than others with the original gene. Those that do better eventually replace the original stock. While it may be possible to explain the difference between a human and a cat with natural selection, you would have to go some to explain the difference between a cat and a fly, or a cat and a tree.
If it is a fact that evolution has occurred and is occurring, why don't biologists call it the Law of Evolution? Biologists tend to be more conservative than physicists or economists. While there is an excellent case for the Law of Gravity being a natural law, the Law of Supply and Demand seems to me to be only sort-of true. While biologists are positive that evolution occurred, they are reluctant to imply, by the use of the word "law," that they know exactly how it occurred.
The idea that the occurrence of evolution is a theory which has not been proved is kept alive by the fundamentalist clergy. Their anti-evolution stand is based on a literal interpretation of The Bible. If the earth, sun, animals, trees and man were not created as described in the Book of Genesis, then the idea that the Bible is the literal word of God is called into question. They are right -it most certainly is!
Charles Darwin worked in the middle of the last century. At that time almost everyone in England believed in the Hebrew myth of the creation. Usher, Archbishop of Armagh, had calculated that the earth was created in 4004 B.C. and this date was placed in the English Bible. Most people believed it then. I don't know how many people still believe it.
The geologist Charles Lyell pointed out that it was obvious that the earth was very very old and that the biblical version of the creation could not to be taken literally. Estimates of the age of the earth, and the life on it, have varied and will change as new evidence comes in. We can be absolutely certain, however, that it will be measured in millions and billions of years; not in thousands.
Darwin knew very little about the mechanism of inheritance. While Gregor Mendel, the discoverer of the laws of inheritance, was a contemporary of his, Mendel's brilliant work was not recognized until the beginning of this century. Darwin based his argument for the evolution of all species on a number of clearly observable facts. For example, animal breeders were continuing to evolve new breeds and Darwin pointed out that if a greyhound and a bulldog were found in nature, they would be considered as unrelated to any known wild species. That they are closely related is shown by the fact that they can interbreed and will have fertile offspring.
Now that we know about the existence of genes and how they are transmitted from generation to generation, it is possible to show how traits are inherited. We also know that genes change by the process called mutation and how mutations occur. By understanding the business of mutation and selection, it is possible to prove that human evolution is occurring NOW. It is also possible to show that evolution has occurred within our relatively recent history. Modern methods of genetic analysis show that man and the chimpanzee are close relatives, having most of their genes in common. Another clincher is the fact that the embryological development in all vertebrates is similar. Yes, we are not only related to the chimpanzee, but to the guppy. You might counter that it is the only possible way that an animal can develop. However, the embryology of insects is completely different from that of vertebrates, as is the embryology of plants.
Since actually looking into the prehistoric past is as impossible as looking into the future, we will never know for sure how man, or any other animal, evolved. We can only make educated guesses from the available evidence. But, that man did evolve, there is no doubt whatever. There is also no doubt that man evolved from non-human species.
I could prove to anyone with an open mind that evolution, in man, is occurring now and has occurred in the past. I couldn't do it in a short column; it would take a bit of time. Unfortunately, you can't prove anything to someone with a closed mind. If a person insists that the earth is flat, no amount of argument is going to change his mind, including the pictures taken from satellites. If someone believes that man was created in an instant, rather than evolving over millions of years from some other form, no amount of evidence will change his mind.
There are a few things that I am absolutely sure of: the moon isn't made of green cheese, the earth is not flat, and the biblical version of the creation is impossible.
Fundamentalists of the militant religions have been ridiculing the folklore of other cultures for hundreds of years. It has even been "you believe what I believe or we will kill you". Now the California State Superintendent of Schools does not believe that fundamentalist beliefs should be subject to ridicule in science classes --an inevitable consequence of teaching the truth about the origin of man-- and proposes modifying the way that evolution is taught in science textbooks.
I suppose that we should be kind to children who believe in Santa Clause, elves, fairies, the omnipotence of parents and the literal truth of folklore. To let these people influence what is taught in science courses, or is written in science text books, is nothing short of idiotic.
Return to the Science Home Page
Return to Ira's Home Page