What is the theory of evolution?

In the natural sciences and other studies a “hypo-thesis” is literally a “below-thesis,” meaning the person thinks it may be tested and accepted.


A “thesis,” is something a person considers a good explanation and that they are willing to debate.

Beyond a “thesis” is a “theory.” That is an explanation that has been questioned repeatedly. Facts, data and information are used to support that explanation or conclusion. Today, in the biological sciences, the “theory of evolution,” is almost unanimously accepted as being the best explanation we have for what has happened in the history of living things on planet Earth.

This explanation is really quite simple. It says that over time, as the environment, climate and populations change, some individual living things reproduce more than others and contribute more to the “gene pool,” which is the available genetic population. There is no “plan” in all this. It is simply variation in reproduction. At one point in time, some living creatures may be highly adapted to their environment, and others not quite as well adapted or productive of offspring. But as the world in which they live changes, those that were not so well-adapted may be better adapted to the new situation and reproduce more.

Time after time, over more than a century, scientists have found that this appears to be true for everything from bacteria, to insects, fish, animals and even humans. That is what makes it a “theory,” rather than some possible “thesis” that a person tries to defend. It is accepted as the best explanation possible at the present time. It is the way living things came to be the way they are.

In contrast there are various explanations around the world, that the world in which we live today, was “created,” at a point in time according to a plan by a creator. One of the most popular in the Western world is found in the Book of Genesis in the Old Testament. There, it seems to say that the world, or planet Earth and all living beings, were created in a relatively short period of time of six days, just as we know them today.

Since this explanation comes from the Hebrew tradition, more than 50 years ago, I asked a wise Jewish rabbi, for his explanation. He said that it was not intended to be a scientific explanation of current life. It was a message to his people that there is only one God, that He created all places as they saw them in the ancient past, in the first three days. Through the next three days He created all living things. That all He created was “good.” This was their explanation as God’s chosen people. It is their belief.

Over the decades I have read great accounts of Raven and creation among indigenous people to explain why living beings are the way they are. The Japanese, Hindus, Muslims and others have their stories of creation. They are all based on what they knew at the time in the past. They are not “theses,” nor “theories,” tested and verified over time, through debate. They are nice explanations that have been passed on for generations in folklore based on what was known in the past. For many, they are beliefs.

The theory of evolution is not a belief. It is an acceptance by those who have questioned, challenged and tested the explanation. It seems to be the best real explanation we have at the present time. We may pass on to our children “beliefs,” but to compete intellectually in the modern world, they have to be shown the best verifiable explanation possible.

• Olson is a professor of anthropology (emeritus) at the University of Alaska Southeast and an elected fellow of the American Anthropological Association.


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