In this essay, I will explain how Darwin’s theory of natural selection has effectively changed people’s conception of the biological nature of reality. Firstly, I will show that it removes the purpose from the world by considering the appearance of design as a mindless mechanical causation, which denies the existence of an intelligent designer and thus demystifies the adaptation of nature. Secondly, I will explain how it changes the view of humanity progress by considering the evolutionary progress in the local sense and adaptability as an environmental contingent trait.

The biological nature is composed of various organisms, and each of them has complex functions which seem to be designed to have the purpose of fitting organisms well into the environment, which we call “adaptation” today. Before Darwin, the explanation of this diversity, complexity and appearance of purpose of design in nature was dominated by teleology. One representative view is Paley’s argument from design. This argument appeals these features in the realm of living things to the existence of an omnipotent, omniscient and benevolent divine designer, namely the theistic God, who implements the design. Darwin’s theory of natural selection also tries to explain the same set of data with all three of these features, but in a non-teleological view.

Firstly, one of the fundamental assumptions of natural selection is that the appearance of design is produced by a purely causal, mechanical and non-intentional process of random variation combined with passive environmental filtration.

In particular, in contrast to Paley’s argument that the novel traits are directed by a designer, Darwin proposes that they occur at random. In Darwin’s view, the variations in every hereditary trait of an organism are not causally driven by any needs, benefits or advantage or with any foresights or intentions, but rather a random event. In this sense, the appearance of novel traits is not directed by a designer to make the organism better fitted in the environment.

Moreover, Argument from Design implies that the environment positively generates the best adapted traits, while Darwin denies any purpose in the environment. Natural selection is a passive process such that the environment passively filters traits that are mostly maladapted. As organisms reproduce, the genes of these “worst” traits are unlikely to be preserved in the next generation, so their proportion in the population is shrinking. To the contrary, the other “better” traits pass on to the next generations and gradually dominate the population. For example, it is not the arctic environment that picks the white bear, but the bears of other colors are not likely to survive since they cannot blend in white environment.

Finally, the Argument from Design contradicts with the fact of the presence of imperfect adaptations, which, however, can be nicely explained by random variation and passive filtration of natural selection. For example, our eye is not perfect as it has a blind spot in which the optic nerve attaches to the back of the retina, resulting in its insensitivity to light. According to Darwin’s theory, many kinds of adaptions have to occur for survival and reproduction, and the solutions to the adaption have to be “quick and dirty” to prevent extinction during the struggle with the environment. Since the “solutions” only emerge by random chance, they might not be the best ones, but the ones that occur first to be just good enough to survive are selected for. Once a “quick and dirty” solution works in the environment, it is inherited by subsequent generations and becomes hard to get rid of. On the other hand, if there is an omnipotent, omniscient and benevolent designer as the teleogists suggest, then this kind of adaptations should not have been existent.

Secondly, natural selection challenges the Argument from Design by taking away “purpose” from the world, so man is no longer considered to be designed to be perfect. Therefore, the worldview of humanity as well as the evolutionary progress is altered, as natural selection does not rank the level of evolution by the appearance of complexity or the superiority in a given environment.

Before Darwin, human beings are considered to represent the highest achievement of evolutionary progression as they are at the top of the organismal hierarchy. Darwin rejects this view. He never accepts the notion of higher and lower species, or ones that have seen more progress versus ones that have seen less, although Darwin’s theory accepts the views about progress which included evolutionary speculations about the upward progress of living things from primordial beginnings.

Moreover, Argument from Design considers the evolution of species is directed by a divine designer, which implies the process of adaptation is forever progressing. However, natural selection considers the progress in a local sense. In Darwin’s view, there is no long-term, locked-in progress in evolution. The environment can change, leading the best adaptation to maladaptation, or even extinction. For example, the dinosaurs were the dominant terrestrial vertebrates on the earth for 135 million years, but later the radical alteration of environment led to the extinction of most dinosaur groups. In addition, adaptation makes some traits well-suited for a particular environment, but these traits could be a disadvantage if put in another environment. For example, the polar bear with its white coat shows its high adaptability in the Arctic Pole, but in the forest, its white color would contrast sharply with the environment, which would make them an inefficient predator and easier to be shot by hunters.

To conclude, Darwin’s theory denies a teleological explanation of the complexity, diversity and appearance of purpose of the living world, and provides a causal mechanical explanation. It proposes that the appearance of purpose in nature is not designed by some divine intelligence, and human beings are not “pre-programmed” by God to progress, or to be the best of all creatures, as it considers adaptability as an environmentally contingent trait.