Vision evolution studied in new paper

Opsins, the light-sensitive proteins key to vision, may have evolved earlier and undergone fewer genetic changes than previously believed. Scientists explain this in a new study from the National University of Ireland Maynooth and the University of Bristol. They published it today in Proceedings of the National Academy of Sciences (PNAS).

The study used computer modeling to provide a detailed picture of how and when opsins evolved. It sheds light on the origin of sight in animals, including humans. The evolutionary origins of vision remain hotly debated, partly due to inconsistent reports of phylogenetic relationships among the earliest opsin-possessing animals.

Dr. Davide Pisani of Bristol’s School of Earth Sciences and colleagues at NUI Maynooth performed a computational analysis to test every hypothesis of opsin evolution proposed to date. The analysis incorporated all available genomic information from all relevant animal lineages. These included a newly sequenced group of sponges (Oscarella carmela). As well, they investigated cnidarians, a group of animals thought to have possessed the world’s earliest eyes.

Using this information, the researchers developed a timeline with an opsin ancestor common to all groups appearing some 700 million years ago. Although this opsin was considered ‘blind,’ yet it underwent key genetic changes over the span of 11 million years. These changes conveyed the ability to detect light.

Dr. Pisani 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. This is an astonishing discovery because it implies that our study uncovered, in consequence, how and when vision evolved in humans.

Original paper can be found here: PNAS

Via University of Bristol