The Origin of Species

In nature, species are limited in their ability to survive by geological shifts, geographical boundaries, and the availability of resources such as food, water, and shelter. Natural disasters can alter the environment in which a population lives, destroying species and allowing others to live. As a result, there is a struggle for existence, in which species must compete with one another to survive. The process of natural selection determines whether a variation that arises better enables a species to compete with others in a specific environment. In Darwin’s view, nature controls the selection of adaptations, making species progress toward perfection.

In domestic breeding, however, humans try to determine whether a variation is advantageous. Human breeders select the specific traits that are allowed to perpetuate in future generations. These traits do not necessarily make it easier for the species to survive and are not influenced by the pressures that are present in nature. Darwin points out that whereas nature also moves species closer to perfection, humans cannot shape their domestic species with nearly as much success.

On first glance, Darwin’s theory seems directly opposed to religious doctrine. Much of Darwin’s argument directly refutes the claims of contemporary natural theology, which states that species are created independent of their environment and argues that their perfect adaptations are proof that a higher power has crafted them. Darwin contradicts the accepted biblical account of creation by denying that species were independently created and by arguing that nature itself is the higher power that shapes species. Critics at the time pointed out that the idea of natural selection seems to deny the role of a creator (such as the Christian God) in shaping individual species. Darwin is also occasionally impatient with religion. He derides the theories of natural theologians, arguing that it is silly to deny scientific evidence that so clearly demonstrates that species descended from one another. He implies that it is scientific inquiry, rather than religiosity and dogma, that allows us to understand the natural world in general and species formation in particular.

At the same time, though, Darwin leaves room for God’s role in the creation of species. While he argues that all species descended from one or more original forms, he does not propose a scientific explanation for how these original forms were created. He suggests that an initial creator “breathed life” into a few original species. At times Darwin refers to the process of natural selection and the descent of species from one another as the “work of God,” suggesting that a deity planned or is overseeing the process of natural selection. Whether Darwin’s references to God stem from his own personal beliefs or from a calculated effort to calm his religious critics is unclear. In either case, the result is that both a secular and a nonsecular interpretation of the theory of natural selection exist in Darwin’s text.

Darwin is dedicated to using the scientific method, which is rooted in observation of the physical world, to explicate his theories of natural selection and descent with modification. At every turn, he supports his theory using inductive reasoning, drawing conclusions and general principles from observable fact and experience. He draws on his own scientific observation on the H.M.S. Beagle or during experiments conducted afterward. For example, he points to the existence of unique species on islands such as Galapagos as evidence of the role of geographical isolation in the modification of species. Darwin also supports his claim that behaviors are heritable by citing his experiments with hive bees, which proved that wax carving is an inherent instinct, rather than a random occurrence or a learned mannerism. By relying heavily on empirical evidence, Darwin demonstrates that observation and experimentation are critical to an understanding of the natural world.