"Struggle for Existence" is the title of the third chapter of On the Origin of Species by Means of Natural Selection by Charles Darwin. It is also the title of the third chapter of Darwin's Ghost by Steve Jones, which parallels The Origin of Species.
This chapter of The Origin of Species is to me a particularly fascinating one. Darwin uses this chapter to express the complexity of nature, and the constant death it encompasses. "[O]f the many individuals of any species which are periodically born," he writes, "but a small number can survive." We often do not understand this, because, as Darwin writes later in the chapter, "[o]ur familiarity with the larger domestic animals tends, I think, to mislead us: we see no great destruction falling on them, and we forget that thousands are annually slaughtered for food, and that in a state of nature an equal number would have somehow to be disposed of."
This is perhaps why Darwin’s theories are so hard to comprehend as a part of reality; they make sense academically, and they fit together with each other and with the rest of our knowledge of the world, but something still seems wrong nonetheless. Survival of the fittest can only be an effective mechanism for evolution if the less fit don’t survive, and this isn’t the world we see.
Most animals we are in contact with, not to mention people, don’t die young. Most live a long time, have children, and die of old age. And, when we look at nature, we do not usually see the death that is necessary for natural selection to work. To quote Darwin again, "We behold the face of nature with gladness, we often see superabundance of food; we do not see, or we forget, that the birds which are idly singing round us mostly live on insects or seeds, and are thus constantly destroying life; or we forget how largely these songsters, or their eggs, or their nestlings, are destroyed by birds and beasts of prey; we do not always bear in mind, that though food may be now superabundant, it is not so at all seasons of each recurring year."
Throughout this chapter, Darwin drives in the point that without this struggle for existence, caused by shortages of food, droughts, predators, and other difficulties, the population of any species would "almost instantaneously increase to any amount." The struggle for existence is a necessary part of nature, for if the difficulties of nature were greatly reduced, then all populations would grow indefinitely, or at least tremendously. If this happened, they would be forced to struggle for the limited resources in existence, and a new balance of nature would be achieved.
Comparing Darwin’s and Jones’ chapters, I think that Darwin’s was much better written. Also, Darwin’s Ghost introduces few new ideas in this chapter, as even at the time of Darwin the idea of a struggle for existence was not a new one. Because I found The Origin of Species to handle this chapter so well, I have not quoted from Darwin’s Ghost at all in this essay.
Both books, however, spend some of this chapter on more complicated examples of the struggle for existence in nature, and the interconnectedness of various species. For instance, Darwin writes that the heartsease and red clover are flowers that are fertilized only by humblebees. "[I]f the whole genus of humble-bees became extinct or very rare in England," he writes, "the heartsease and red clover would become very rare, or wholly disappear. The number of humble-bees in any district depends in a great degree on the number of field-mice, which destroy their combs and nests." Since the number of mice in an area is to some extent dependent on the number of cats, places with more cats will have fewer mice, and therefore more humble-bees, and therefore more heartsease and red clover.
Darwin’s point in these examples is that nature operates through complex systems which are for the most part beyond our understanding. The red clover depends not only on several animals for its existence, but on climate, soil conditions, and any number of other factors. This should "convince us of our ignorance on the mutual relations of all organic beings; a conviction as necessary, as it seems to be difficult to acquire."
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