Opsins developed earlier than thought, leading to sight The eye of a cuttlefish. Credit: University of Bristol BRISTOL, England, Oct. 30 (UPI) -- British and Irish researchers say their studies have shed light on how and when vision evolved, and that it may have evolved earlier than previously thought. Scientists at the University of Bristol and the National University of Ireland Maynooth used computer modeling to provide a detailed picture of how and when opsins -- light-sensitive proteins key to vision -- evolved, eventually leading to the origin of sight in animals, including humans. Their model analyzed all available genomic information from all relevant animal lineages, including a newly sequenced group of sponges and the Cnidarians, a group of animals including sea anemones and jellyfish thought to have possessed the world's earliest eyes, a Bristol release said Monday. The model yielded a timeline with an opsin ancestor common to all groups appearing some 700 million years ago. While this opsin was considered "blind" it underwent key genetic changes over the span of 11 million years that conveyed the ability to detect light, the researchers said. "The great relevance of our study is that we traced the earliest origin of vision and we found that it originated only once in animals," researcher Davide Pisani of Bristol's School of Earth Sciences said. This is an astonishing discovery because it implies that our study uncovered, in consequence, how and when vision evolved in humans.