Scientists track evolution of sight
Scientists have traced the origin of eyes back to a transparent blob of living jelly floating in the sea about 600 million years ago.
That creature, the distant ancestor of a modern freshwater animal known as a hydra, could only distinguish light from dark.
But that simple trick was such an advantage that it was passed on from generation to generation of the hydra's cousins and their myriad descendants. It was the precursor of the wildly ...
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