Darwin and Spencer on the Theory of Natural Selection
While it is true that accidents account for many deaths of individuals in any given species, evolutionary scientists have proven that many traits and hereditary propensities do not enable the individual to withstand factors in the environs in which he dwells, particularly the battle for survival that particularly marks the life and death of animals. Naturally, what may be called chance or accident leads to the deaths of individuals who otherwise would well suited to live, but given that this process goes on continuously over long stretches of time, we find that at some point a genetic disposition will begin to emerge.
Herbert Spencer labeled this phenomenon the “survival of the fittest,” and although the term may not be completely precise in the example of any one species in any one time period, when we view that the battle is going on every year, during the full lifespan of each species, we cannot doubt that generally speaking those who survive are among the fittest. The struggel for survival is so severe and so sustained that the most minior flaw in any sense organ and any physical imperfection will almost certainly, at one time or another, be fatal.
This relentless weeding out of the less fit, in every generation will produce two diverse results, which need to be clearly distinguished. The first is the preservation of each species in the fullest state of adjustment to the circumstances of its existence. As long as these conditions are left unchanged, the effect of natural selection is to maintain each well-adapted species unchanged.
The second effect develops whenever the conditions change. The most fit individual will adapt more successfully, and the regular process of natural selection will occur more quickly, according to the conditions. This process will eventually bring about complete adjustment to the new conditions. Some writers allow for pure chance, but observe that the action of natural selection in weeding out the less fit and thus retaining every species in the best state of efficiency.
The subject of natural selection and survival of the fittest does not figure largely into the contemporary argument between the proponents of evolution theory, intelligent design theory, and creation theory. In the evolution, intelligent design, creationism debate the subject of natural selection is nearly irrelevant, given that evolution theory and intelligent design theory are in reasonable agreement on the matter, while creation theory refuses it altogether.