Charles Darwin, the father of evolution, was the first to publish the idea of natural selection. Natural selection is the mechanism for how evolution occurs over time. Basically, natural selection says that individuals within a population of a species that have favorable adaptations for their environment will live long enough to reproduce and pass down those desirable traits to their offspring. The less favorable adaptations will die off eventually and be removed from the gene pool of that species. Sometimes, these adaptations cause new species to come into existence if the changes are large enough.
Even though this concept should be pretty straight forward and easily understood, there are several misconceptions about what natural selection is and what it means for evolution.
1. Survival of the "Fittest"
Most likely, most of the misconceptions about natural selection come from this single phrase that has become synonymous with natural selection. "Survival of the fittest" is how most people with only a superficial understanding of the process would describe it. While technically, this is a correct statement, the common definition of "fittest" is what seems to create the most problems for understanding the true nature of natural selection.
Although Charles Darwin did use this phrase in a revised edition of his book On the Origin of Species, it was not intended to create confusion. In Darwin's writings, he intended for the word "fittest" to mean those who were most suited to their immediate environment. However, in the modern use of language, "fittest" often means strongest or in best physical condition. This is not necessarily how it works in the natural world when describing natural selection. In fact, the "fittest" individual may actually be much weaker or smaller than others in the population. If the environment favored smaller and weaker individuals, then they would be considered more fit than their stronger and larger counterparts.
2. Natural Selection Skews Toward the "Average"
This is another case of common use of language that causes confusion in what is actually true when it comes to natural selection. A lot of people reason that since most individuals within a species fall into the "average" category, then natural selection must always favor the "average" trait. Isn't that what "average" means?
While that is a definition of "average", it is not necessarily applicable to natural selection. There are cases when natural selection does favor the average. This would be called stabilizing selection. However, there are other cases when the environment would favor one extreme over the other (directional selection) or both extremes and NOT the average (disruptive selection). In those environments, the extremes should be greater in number than the "average" or middle phenotype. Therefore, being an "average" individual is actually not desirable.
3. Charles Darwin Invented Natural Selection
There are several things incorrect about the above statement. First of all, it should be pretty obvious that Charles Darwin did not "invent" natural selection and that it had been going on for billions of years before Charles Darwin was born. Since life had begun on Earth, the environment was putting pressure on individuals to adapt or die out. Those adaptations added up and created all of the biological diversity we have on Earth today, and much more that has since died out through mass extinctions or other means of death.
Another issue with this misconception is that Charles Darwin was not the only one to come up with the idea of natural selection. In fact, another scientist named Alfred Russel Wallace was working on the exact same thing at the exact same time as Darwin. The first known public explanation of natural selection was actually a joint presentation between both Darwin and Wallace. However, Darwin gets all the credit because he was the first to publish a book on the topic.
4. Natural Selection is the Only Mechanism for Evolution
While natural selection is the largest driving force behind evolution, it is not the only mechanism for how evolution occurs. Humans are impatient and evolution through natural selection takes an extremely long time to work. Also, humans seem to not like to rely on letting nature take its course in some cases.
This is where artificial selection comes in. Artificial selection is a human activity designed to choose the traits that are desirable for species whether it be color of flowers or breeds of dogs. Nature is not the only thing that can decide what is a favorable trait and what is not. Most of the time, human involvement and artificial selection is for aesthetics, but it can be used for agriculture and other important means.
5. Unfavorable Traits Will Always Disappear
While this should happen, theoretically, when applying knowledge of what natural selection is and what it does over time, we know this is not the case. It would be nice if this did happen because that would mean any genetic diseases or disorders would disappear out of the population. Unfortunately, that does not seem to be the case from what we know right now.
There will always be unfavorable adaptations or traits in the gene pool or natural selection would not have anything to select against. In order for natural selection to happen, there has to be something more favorable and something less favorable. Without the diversity, there is nothing to select or to select against. Therefore, it seems like genetic diseases are here to stay.