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The human eye is a remarkable feat of engineering, but from the outside the main thing we notice is the colour. Eye colour is partly dictated by a gene on chromosome 15 called OCA2, which gives instructions for the production of a pigment called melanin. Dr Tim Cockerill explains how different amounts of melanin lead to different eye colours, and how the production of blue eyes can be explained in the same way as the blue in our skies.

With thanks to BBSRC: http://bbsrc.ac.uk/

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