If I asked you what colour you see when you look at a leaf in the spring, your answer would most likely be “green”. What if, instead of only being able to see a plain green leaf, you had the amazing ability to see a rainbow of breathtaking colours contained within that one leaf?
The extraordinary power of tetrachromacy enables people who have it to see around 100 million colours ; in comparison, normal people can see around 1 million colours. People with tetrachromacy have four types of cones – the cells in our eyes that allow us to see colours – instead of the usual three. This allows them to see a much wider range of colours than most people.
Tetrachromacy is produced by a genetic mutation on the X chromosome. However, the mutation must be present on both of a person’s X chromosomes in order for that person to have four types of cones. This means tetrachromacy is only possible for most women, who have two X chromosomes, and men with Klinefelter syndrome, who have two X chromosomes and one Y chromosome. Therefore, most men, who only have one X chromosome and one Y chromosome, cannot be tetrachromats.
Also, even if someone has four types of cone cells, it does not mean that they will automatically be a tetrachromat. If a person does have four cone types, but has not been immersed in a wide variety of colours from an early age, they might not have developed the capability to harness their power. Scientists currently believe that around 12% of women have four types of cones, but that the overwhelming majority of those people do not have actual tetrachromatic abilities.
Dr. Gabriele Jordan is one of the world’s leading researchers on tetrachromacy. She has been studying the topic for more than 20 years, but until relatively recently, she had not made any significant conclusions. So, in 2007, she tried a different method of testing. She used a group of women who each had four cone cell types as her test subjects. She repeatedly flashed three different circles of light in front of her subjects. Two of the circles contained the exact same colour, but one had a subtle difference in colour, so subtle, in fact, that only a tetrachromat would be able to distinguish it from the other two. Out of the whole group, only one woman, identified as Subject cDa29, was able to identify the circle that had the different colour every single time. Jordan was overjoyed – she had finally found a real tetrachromat!
Concetta Antico, an artist from Los Angeles, California, is one of the world’s only two confirmed tetrachromats, in addition to Subject cDa29. Ever since Antico was a child, she was fascinated by all the colours she could see. From a very early age, she loved to paint all the beautiful things she could see around her; she also loved to be outside in nature, collecting various objects, since she was mesmerized by all the colours she could see in them. When she grew up, she became an art teacher. One of her students came to her, having read an article about tetrachromats, and told her that he thought she was one. Antico didn’t think it was possible, so she ignored the idea for some time. She later found out that her daughter was colourblind. Then, after a few years, a neurologist named Dr. Wendy Martin started taking art lessons from Antico. Dr. Martin told Antico that her artwork was indescribably beautiful in regard to its use of colour. That was when Antico remembered what her student had told her years earlier. She told Dr. Martin about the article, and two weeks later, Dr. Martin sent her another article about the potential for colour blindness in tetrachromats’ children. Antico contacted the doctors who had been cited in the article, and they tested her for tetrachromacy; the result was positive. She has continued to volunteer for research studies about tetrachromacy to this very day.
I first learned about tetrachromacy while researching unique genetic mutations for a school project. Since my own eyesight is quite bad, I was very interested in what it would be like to have superhuman eyesight like tetrachromats do.
In conclusion, tetrachromacy is a rare and fascinating ability that allows people to see 100 times the amount of colours that normal people can see. Research on tetrachromacy continues to be done to this day, and I am excited to hear about further developments on this topic.