The origin of our eyes: when our ancestors were cyclops

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For decades, the eye has been one of evolution's great enigmas. Charles Darwin said that thinking about the origin of such a sophisticated organ made him shudder. How could a structure capable of detecting light have been built in such a way that the brain could form three-dimensional images with which to interpret the world, from the accumulation of small and gradual changes? A new scientific hypothesis published in the journal Current Biology proposes a surprising answer. Our eyes could come from a single ancestral eye located in the center of the head in very simple marine animals. Perhaps it is no coincidence that so many ancient mythologies imagined cyclops, beings with a single eye in the center of the forehead. Long before vertebrates with two lateral eyes existed, our ancestors might have actually had a single primitive central eye.The research, led by neurobiologists Dan-Eric Nilsson (Lund University, Sweden) and Tom Baden (University of Sussex, England), suggests that about 560 million years ago, the ancestors of vertebrates had a single central photosensitive system, similar to a “third eye”. Over time, this organ split into two, which gradually specialized to give rise to modern retinas.