How Our vision Made us Human Being.

IT TOOK a rather unremarkable garment for people to begin to question their view of reality. On 26 February this year, a photo of a dress went viral – not for its stylishness, but because of its chameleonic colours. Some saw it as blue and black, while others thought it white and gold. Still others, to their enduring unease, saw first one combination, then the other.

The discussions that rippled across the web as a result illustrated a fundamental truth: colour is one of the most vivid and personal experiences we have. But while colour feels extremely real and present, we are still learning exactly how events in our evolutionary past combined to create our particular form of colour vision – and beyond the odd optical illusion, just how important it has been in making us who we are. "Humans wouldn't be here if we ...