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Hot Topic Origins Origin & Evolution of Life Vision Evolved Only Once in Animals?
 
Vision Evolved Only Once in Animals?
Source: University of Bristol press release
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Origin & Evolution of Life
Posted:   10/31/12

Summary: A new study provides a detailed picture of how opsins evolved. Opsins are light-sensitive molecules found in photoreceptor cells of the retina.


The new study may help scientists determine when vision evolved in humans. Image: Aaron L. Gronstal
The study, which used computer modelling to provide a detailed picture of how and when opsins evolved, 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 eye of a cuttlefish. Credit: University of Bristol
The analysis incorporated all available genomic information from all relevant animal lineages, including a newly sequenced group of sponges (Oscarella carmela) and the 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. This opsin was considered 'blind' yet underwent key genetic changes over the span of 11 million years that 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."

This story has been translated into Portuguese.


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