Scientists have found a woman whose eyes have a whole new type of colour receptor

After more than 25 years of searching, neuroscientists in the UK recently announced that they've discovered a woman who has an extra type of cone cell - the receptor cells that detect colour - in her eyes. According to estimates, that means she can see an incredible 99 million more colours than the rest of us, and the scientists think she's just one of a number of people with super-vision, which they call "tetrachromats", living amongst us.

Most humans are trichromats, which means we have three types of cone cells in our eyes.
Each type of cone cell is thought to be able to distinguish around 100 shades, so when you factor in all the possible combinations of these three cone cells combined, it means we can distinguish around 1 million different colours.

Most people who are colour blind only have two functioning types of cone cells, which is why they can only see around 10,000 shades - and almost all other mammals, including dogs and New World monkeys, are also dichromats.
But there's one doctor in northern England who has four cone cell types, taking the potential number of colours she can distinguish up to 100 million - colours most of us have never even dreamed of.

Identified only as cDa29, the scientists finally found this woman two years ago, but they've been searching for more than 25 year - and think there are more tetrachromats like her out there.
So how do you get a fourth type of cone cell?

http://www.sciencealert.com/scientists-have-found-a-woman-whose-eyes-have-a-whole-new-type-of-colour-receptor

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