Darwin's chief influence was on Naturalism, a form of realism that emerged in the late nineteenth century and was championed by writers such as Thomas Hardy, who saw humankind not as the crown of God's creation but as a tiny speck caught amid the larger, impersonal forces of nature.

In Hardy's novels, nature is depicted as indifferent to humankind and human suffering. There is no God that acts as a deus ex machina or intecessor, looking out for the well-being of characters by intervening to help them. In Tess of the d'Urbervilles, for example, a mere twist of fate keeps her from turning to Angel's family for help—and they would have helped her. In Far From the Madding Crowd, nothing intervenes to save Gabriel Oak's flock of sheep from being herded over the side of a cliff and to their deaths by an overzealous dog. In Jude the Obscure, the idea that there is a "destiny" calling Jude to Oxford is shown to be an illusion.

Darwinism—the idea of nature as entity separated from God—influenced literature away from coincidences, which were so beloved of Victorian novelists like Dickens, and away from contrived happy endings. Darwinism encouraged writers to take a "let the chips fall where they will" attitude to their characters and plots.

I think Darwin's theories were just a piece of the way scientific thought was being transformed in the latter part of the nineteenth century. After all, preceding him by decades was Mary Shelley's Frankenstein, which itself reflects a transformational look at how humans interact with scientific knowledge. DNA was first identified by a Swiss chemist named Friedrich Miescher around the same time that On the Origin of Species was published. Hermann Ludwig Ferdinand von Helmholtz was also a contemporary, forever changing scientific thought with his principle of the law of conservation of energy.

So I would argue that Darwin found himself in the midst of a shifting perspective of scientific influences, and this shift can also be found in the literature of that century. Early in the 1800s, Jane Austen was scripting novels like Pride and Prejudice, which is a work of Romantic literature (popular during this period) and focused on an emotional response and the innate goodness of nature.

As Darwin's theories became more well-known, this sentiment began to shift toward the latter part of the century. An emotional connection to literature was replaced by novels reflecting reasoning and judgement. The Strange Case of Dr. Jekyll and Mr. Hyde, the story of a scientist's desire to eliminate human evil, was published in the late 1800s; the fact that Stevenson was contemplating the origin of human evil and that there could be a scientific means of eliminating it reflects this new scientific thought. Another scientist appears in The Invisible Man; this time, the quest is to make oneself invisible. Again, Wells was testing the limits of what could be possible through new understandings of science.

I would argue that ideas such as the capacity of the strongest individuals to survive shows up in literature such as The Adventures of Huckleberry Finn and even in the poetry of Emily Dickinson. Darwin's theories reshaped human thought by allowing people to see the ever-changing nature of human capacities, and these types of characters are also reflected in works such as A Doll's House and A Christmas Carol—works where the protagonists completely transform their character by the plot's conclusion.

I think that one of the most profound examples of Darwinian thought impacting artistic and political reality was in how the role of human beings were reconfigured.  On one hand, those who believed in the divine having a role in human creation were dealt a stunning blow by Darwin's scientific theory of evolution.  Similar to Copernicus and Galileo who used science to present a rationalist view that denied human exceptionalism, Darwin was able to confirm to secularists that their beliefs were grounded in rational thought. English critic Thomas Huxley argued as much:

What if the orbit of Darwinism should be a little too circular? What if species should offer residual phænomena, here and there, not explicable by natural selection? Twenty years hence naturalists may be in a position to say whether this is, or is not, the case; but in either event they will owe the author of "The Origin of Species" an immense debt of gratitude.

Yet, the flip side to this is that Darwin's application and thought confirmed precisely that there was little sense of wonderment in human beings.  This helped to enhance the growing feel of modernism and alienation from a configuration or order that professed structure and unity in human consciousness.  Along these lines, Darwinian thought became manipulated by the proponents of Social Darwinism and its misapplication of "survival of the fittest."  In this light, one can see the profound impact of Darwinian thought on English and European literature of the 19th century.