Tuesday, November 13, 2012

Vision Evolution




 700,000,000 years ago one single act of origination started us down the road to having vision. That it appears unique is interesting unless there is a reason it is hard. I would prefer easy and multiple originations and a sorting out.

It is still a long time ago and reminds us of the antiquity of our core biological toolkit inheritance.

Everything began as a cellular application with huge variation possible. Recall that natural selection works wonderfully at the cellular level. It is much more doubtful thereafter. Then the organism is unconsciously able to modify his offspring and we get an evolution of successful choices instead.

New study sheds light on how and when vision evolved

by Staff Writers

Bristol UK (SPX) Oct 31, 2012

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 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."

Paper: 'Metazoan opsin evolution reveals a simple route to animal vision' by Roberto Fueda, Sinead C. Hamilton, James O. McInerney, and Davide Pisani in PNAS.

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