Today is the 200th birthday of Charles Darwin.
It’s often mistakenly said that Darwin developed the theory of evolution. This is not accurate. In the mid-19th century it was widely discussed among many biologists that species seem to have developed from other species. The problem was that there was no known mechanism that could explain how this happens.
Darwin then came along and developed the theory of Natural Selection, a beautiful, comprehensive, and in retrospect obvious explanation. Of course! There is variation among any population. Those individuals who are better able to survive and reproduce will pass on their characteristics to their children, thereby increasing those successful characteristics. From such a simple, self-evident thesis comes the almost infinite variety of life.
Darwin didn’t know how variations came about, but he knew it must happen. It wasn’t until the 20th century that genes and mutations were discovered (though Mendel’s work pointed to genes much earlier), but his theory and the evidence predicted that they must exist. Most mutations are neutral, causing no significant changes in the individual. Many of the rest are harmful, but a few are beneficial. Those beneficial mutations are more likely to be preserved.
Evolution driven by natural selection is not “random”, as is often claimed: “You might just as well expect a jetliner to be produced by a tornado passing through a junkyard, as for a human being to arise from random chance!” It is not chance; it’s a slow, gradual process molded and directed at each step by the selection of the environment.
There are no serious biologists working in the world today who doubt evolution, or that natural selection is the main driving force behind it. To say that it’s “just a theory” means that all the evidence supports it and that it is the best known explanation. You might just as well say that the theory of Gravitation is “just a theory”, or the sun-centered solar system is “just a theory”. All known evidence supports the theory, and those who oppose it do so from religious or philosophical grounds, not factual.
So Happy Birthday, Charles Darwin, and thanks. Eventually someone else would have put it together as you did, but it might have taken a lot longer, and delayed the progress of the biological sciences.