Survival of the Fittest vs. Natural Selection

It is important to understand what Darwin meant by 'fittest'

Darwinism, Natural Selection of Living Organisms, lithograph, published in 1897

ZU_09 / Getty Images

When Charles Darwin was coming up with the Theory of Evolution, he had to find a mechanism that drove evolution. Many other scientists, such as Jean-Baptiste Lamarck, had already described the change in species over time, but they didn't offer explanations as to how it occurred. Darwin and Alfred Russel Wallace independently came up with the idea of natural selection to fill that void.

Natural Selection vs. 'Survival of the Fittest'

Natural selection is the idea that species that acquire adaptations favorable for their environment will pass those adaptations to their offspring. Eventually, only individuals with those favorable adaptations will survive, which is how the species changes over time or evolves through speciation.

In the 1800s, after Darwin first published his book "On the Origin of Species," British economist Herbert Spencer used the term "survival of the fittest" in relation to Darwin's idea of natural selection as he compared Darwin's theory to an economic principle in one of his books. This interpretation of natural selection caught on, and Darwin used the phrase in a later edition of "On the Origin of Species." Darwin used the term as it was meant regarding natural selection. Nowadays, however, the term is often misunderstood when used in place of natural selection.

Public Misconception of 'Fittest'

Members of the public might be able to describe natural selection as survival of the fittest. Pressed for further explanation of the term, however, most answer incorrectly. Someone not familiar with what natural selection really is might take "fittest" to mean the best physical specimen of the species and that only those in the best shape and best health will survive in nature.

That isn't always the case. Individuals that survive aren't always the strongest, fastest, or smartest. By that definition, then, survival of the fittest might not be the best way to describe natural selection as it applies to evolution. Darwin didn't mean it in those terms when he used it in his republished book. He intended "fittest" to mean the members of the species best suited for the immediate environment, the basis of the idea of natural selection.

Favorable and Unfavorable Traits 

Since an individual needs the most favorable traits to survive in the environment, it follows that individuals with favorable adaptations will live long enough to pass their genes to their offspring. Those lacking the favorable traits—the "unfit"—most likely won't live long enough to pass down their unfavorable traits, and eventually, those traits will be bred out of the population.

The unfavorable traits might take many generations to decline in numbers and longer to disappear from the gene pool. This is evident in humans with the genes of fatal diseases; their genes are still in the gene pool even though conditions are unfavorable for their survival.

Remedying the Misunderstanding

Now that this idea is stuck in our lexicon, there isn't much that can be done to help others understand the actual meaning of the phrase beyond explaining the intended definition of the word "fittest" and the context in which it was said. An alternative could be to avoid using the phrase altogether when discussing the Theory of Evolution or natural selection.

It's acceptable for a person to use the term "survival of the fittest" if he or she understands the scientific definition. However, casual use of the phrase by someone without knowledge of natural selection can be misleading. Students who are first learning about evolution and natural selection should avoid using the term until they have a deeper knowledge of the subject.