Darwin’s critics often bring up the topic of eyes, since they seem to be an organ of such complexity that only a Creator could have made them. For Darwin, however, eyes represent exactly the opposite: they show how even a process as slow and gradual as natural selection could lead to results as shockingly organized and elaborate as the eye. He admits that eyes are a formidable challenge to his theory, but crucially, he believes they are a challenge that can be explained. In The Origin of Species, Darwin demonstrates that not all eyes are as complex as the human eye—many organisms have eyes that exist on a spectrum between rudimentary optical nerves and fully developed eyes. The diversity of eyes in living creatures and the fossil record helps make the case that complex eyes did not have to arise all at once but in fact could have easily been the result of gradual, successive adaptations over a long period of time. Additionally, eyes present another, opposite problem for Darwin: why do some organisms that live underground or in caves have nonfunctioning eyes if natural selection favors improvement? Here, Darwin explores the idea that features of an organism that don’t get frequent use will eventually be selected against in natural selection. This is because of the principle of economy of growth—losing eyes that no longer serve a purpose helps an organism adapt in other ways. Ultimately, eyes serve a variety of functions in The Origin of Species and perhaps are especially significant because they can also symbolize observation—and observation was the basis of many of Darwin’s most noteworthy discoveries.
Eyes Quotes in The Origin of Species
To suppose that the eye with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest degree.
As natural selection acts only by the accumulation of slight modifications of structure or instinct, each profitable to the individual under its conditions of life, it may reasonably be asked, how a long and graduated succession of modified architectural instincts, all tending towards the present perfect plan of construction, could have profited the progenitors of the hive-bee? I think the answer is not difficult: cells constructed like those of the bee or the wasp gain in strength, and save much in labour and space, and in the materials of which they are constructed.
Eyes Symbol Timeline in The Origin of Species
