The third chapter of Darwin’s wonderful work is “Struggle for Existence” and is another short but info filled chapter. He’s focusing on how struggle bears on natural selection.
Darwin once again points out the importance of variation:
Owing to this struggle for life, any variation, however slight and from whatever cause proceeding, if it be in any degree profitable to an individual of any species, in its infinitely complex relations to other organic beings and to external nature, will tend to the preservation of that individual, and will generally be inherited by its offspring. The offspring, also, will thus have a better chance of surviving, for, of the many individuals of any species which are periodically born, but a small number can survive. I have called this principle, by which each slight variation, if useful, is preserved, by the term of Natural Selection, in order to mark its relation to man’s power of selection. (64)
The struggle for life is something Darwin found fascinating, yet something that humans tend to easily forget. We don’t bear in mind that everything, even if it appears to be in a state of abundance and health, deals with struggle constantly. On a sunny Spring day, you may see green grass and blooming flowers, several species of singing birds and various mammals relaxing in the sunshine. What you may be missing is the birds’ constant crunching on insects. Maybe, you’re not noticing that the cozy mammals just had a nice midday meal or the stunted plants in between the healthy specimens. Darwin insists that without the understanding of the struggle for existence, we cannot have a full understanding of nature and several biological facts. Darwin also points out that what he means by “Struggle for Existence.” He doesn’t just include physical fighting and bloody death in his definition. He includes interdependence and the success in leaving offspring, along with the struggle against the elements (65).
Darwin spends several pages discussing the struggles of living beings. He also discusses population growth and checks on that growth. He has a wonderful example of the delicate balance in nature and the fact that even a small change can greatly influence populations (pages 72-4 Scotch Fir). This struggle is ongoing, but as Darwin points out, it is so well balanced that we barely notice it. We are amazed when we hear of an extinction event. Or, at least, Darwin was. It’s become quite common place nowadays.
The struggle for existence can seem rather daunting and downright depressing at times. However, we shouldn’t be too disheartened. I’ll let Darwin’s final chapter comments sum up:
All that we can do, is to keep steadily in mind that each organic being is striving to increase at a geometrical ratio; that each at some period of its life, during some season of the year, during each generation or at intervals, has to struggle for life, and to suffer great destruction. When we reflect on this struggle, we may console ourselves with the full belief, that the war of nature is not incessant, that no fear is felt, that death is generally prompt, and that the vigorous, the healthy, and the happy survive and multiply. (78-9)