Charles Darwin, in his 1859 book "On the Origin of Species", described the concept as "the preservation of favoured races in the struggle for life". Survival of the fittest does not imply that the strongest or most aggressive individuals will always survive. Instead, it refers to those individuals that are best suited to their particular environment. For example, in a cold environment, individuals with thicker fur or better insulation may have an advantage over those without. Similarly, individuals with better camouflage may be less likely to be preyed upon.
In evolutionary theory what is meant by survival of the fittest?
In evolutionary theory, the phrase "survival of the fittest" refers to the process by which individuals that are better adapted to their environment are more likely to survive and produce offspring. This concept was first popularised by the English philosopher Herbert Spencer in 1864, as an analogy to natural selection.