Neue Perspektiven über die Entwicklung und Evolution der Augen

In "The Origin of Species" Charles Darwin (1859) proposed that the different eye-types found in the animal kingdom go back to a simple prototype consisting of two cells only, a photoreceptor cell and a pigment cell, which shields the eye from one side. Such a prototypic eye would allow the animal to detect the direction of light. Darwin assumed that the eyes of increasing perfection originated from this prototype by variation and selection.