TIP: We seen evolution in experiments, both in the lab and outside of it (see Experimental evolution). What is natural selection? CrashCourse explores natural selection and survival of the fittest. Let’s look at Darwin’s own words (and the 150 plus years of science that fill in the gaps, Darwin wasn’t 100% right, but today we filled in most of the holes) to help us clarify how survival of the fittest, natural selection, and evolution work. In other words, traits don’t have to be traditionally “useful” to be “fit”. Traits can be useful, or they can hinder the ability of a species to survive.
They largely depend on external factors like food supply, predators, and environmental changes.
īy looking at examples of existing organisms, we can conclude that the genetic traits that make an organism fit for survival can vary widely. We can see many examples of the effects of this natural selection in nature by looking at the ~7.77 million species of animals and ~298,000 species of plants on earth. Organisms with any genetic traits suited to survive their immediate environment are more likely to procreate and pass on their genes. This means in nature, over time, a trait that is “fit” for survival tends to become dominate in a species, regardless of whether it is a generally impressive or useful trait or not. It does not mean “only the most physically strong or mentally strong thrive” and it is not the same thing as “the theory of evolution”, although it does pertain to it. “Survival of the fittest” means that those who are best adapted to their environment thrive and tend to be favored by evolution due to “natural selection”.
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