Evolution of the eye. Scientists now have a clear vision of how our notoriously complex eye came to be.

The eyes of vertebrate animals are so complex that creationists have long argued that they could not have formed by natural selection. Soft tissues rarely fossilize. But by comparing eye structures and embryological development of the eye in vertebrate species, scientists have gained crucial insights into the organ's origin. These findings suggest that our camera-style eye has surprisingly ancient roots and that prior to acquiring the elements necessary to operate as a visual organ it functioned to detect light for modulating our long-ago ancestors' circadian rhythms.