Imagine a life of communal darkness. For those organisms sharing our Earth over 540 million years ago, this was the reality. Or so Science tells us. The progression of the eye is perhaps one of the most argued of topics among evolutionists and one that holds many different hypotheses.
The eye is a prime example of something called irreducible complexity. Simply put, this means that it is such a complex system of exact components that it cannot function properly unless everything is perfectly lined up and in sync. Keeping this in mind, you can see where the arguments and hypotheses for the eye’s evolution would begin – how can something so complex have evolved so perfectly?
Not only has this created heated scientific debates, but it is a lasting argument with Creationists as well. In fact, Charles Darwin’s theory behind the evolution of the eye is generally one of the first that his sceptics will attack. In The Origin of Species, Darwin admits, “To suppose that the eye… could have been formed by natural selection, seems, I freely confess, absurd in the highest degree.” Although Darwin was never able to provide the proof needed for his theory, he did go on to accept that natural selection itself was an adequate explanation, stating “if numerous gradations from a simple and imperfect eye to one complex and perfect can be shown to exist… then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, should not be considered as subversive of the theory.”
So if even Charles Darwin had to leave the eye’s evolution with a question mark hanging over it, what steps could we then begin to take towards learning of the eye’s amazing complexities?
The breakthrough came when the first fossils of eyes were discovered, dating back to the Cambrian period (about 540 million years ago). The rapid state of evolution discovered in these fossils has been christened the “Cambrian explosion”. It is generally agreed that the catalyst behind this “explosion” was, in fact, the drastic rate in evolution of the eye coupled (or caused) by an arms race. Before this period, most organisms lived in a mutual gloom of blindness. Some may have been able to differentiate between light and dark but it is unlikely that any had the visual capabilities of the creatures that followed them.
It is difficult to guess the rate in which the eye then began to evolve. Although a huge breakthrough, the fossil records from this period could only provide minimal knowledge. It is, of course, evident that our eyes would continue to evolve – though, in slow successions or all at once, most will still argue about.