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http://www.nature.com/news/2004/041025/full/041025-18.html
Marine worm sports two kinds of 'eyes'
Vertebrate and insect vision may have evolved from the same precursor.
Darwin famously realized that the eye would be a key test for his theory of evolution by natural selection. He suggested gradual steps from an "imperfect and simple" form, and modern scientists have no trouble believing that the eye evolved from a single light-detecting cell. But they disagree over whether it evolved just once, or many times.
Now the miniscule marine worm Platynereis dumerilii, whose crude light perception seems to have stood it in good stead for millennia, hints at an answer to this question.
Its few light-sensing cells come in two types: one is of a type seen almost exclusively in vertebrates, and one is seen in insects, according to a paper in this week's Science1. Could a worm like Platynereis have been the father of the eye? ...
Marine worm sports two kinds of 'eyes'
Vertebrate and insect vision may have evolved from the same precursor.
Darwin famously realized that the eye would be a key test for his theory of evolution by natural selection. He suggested gradual steps from an "imperfect and simple" form, and modern scientists have no trouble believing that the eye evolved from a single light-detecting cell. But they disagree over whether it evolved just once, or many times.
Now the miniscule marine worm Platynereis dumerilii, whose crude light perception seems to have stood it in good stead for millennia, hints at an answer to this question.
Its few light-sensing cells come in two types: one is of a type seen almost exclusively in vertebrates, and one is seen in insects, according to a paper in this week's Science1. Could a worm like Platynereis have been the father of the eye? ...
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