For many years I was wronged to believe that a colourblind saw the world black and white when a medical student casually asked me to read out some digital configurations. I tried my best. I couldn’t. As I fluttered, I threw in the towels. The eagle-eyed friend read out the hidden digits with surprising ease. Happy with the discovery he declared me colourblind. I was of the most common type, ‘red-green-colourblind’. My green cones won’t detect enough green and were too sensitive to yellows, oranges, and reds. The discovery didn’t make much difference till one evening in the university hostel a research scholar from the Department of Human Genetics and Physical Anthropology, frantically tossed his head. The department, including him, had failed to find a single case of colourblindness. Out of sheer frustration when he narrated the tale of his woes, his joy knew no bounds, when I broke the news that one such case existed right under his very nose. It was a bolt from blue; he jumped out of his skin, drew out chequer-boards, and soon confirmed the veracity of his prize find.
It wasn’t many days before his HOD invited me to his department. As if I were a prize cache, a guinea pig, the chic-looking damsels, and other apron-clad scholars fought amongst them to study my body parts. My blood samples were taken and I was put to a series of weird tests and observations. Within days, I was exposed to the ridicule of the whole campus. As students came to know that I was colourblind everyone wanted to know what I looked like and how the world looked to me. The majority of them thought I saw the world black and white, ditto me, when I would also think so, several years back.
Unlike birds which have excellent colour vision, many mammals have no true colour vision at all. Others, including certain kinds of partially colourblind humans, use a two-colour system based on two kinds of cones. High-quality colour vision with a three-colour system may have evolved in our primate ancestors as an aid to finding fruits in the green forest. The three-colour system is a device invented by certain fruiting trees in order to propagate themselves; an imaginative way of calling attention to the fact that trees benefit from attracting mammals to eat their fruits and spread the seeds. Humans are unusual among mammals for the three different types of photo-pigments we’ve. Most mammals, including dogs, have just two photo-pigment types. Butterflies have more than three. They may be able to see colours we can only imagine. Nobody knows whether or how this benefits them but it may be suggestive that bomber crews in the Second World War liked to include at least one colourblind who could penetrate certain kinds of camouflage on the ground.
The ability to see colour is an important part of being able to see objects in situations where they aren’t clearly set apart from the background, such as oranges in a tree. In modern life, we are also faced with the need to interpret colour-coded information such as signs and lights. People with colour blindness can usually still see colours but have colour confusion or see certain pairs of colours so similarly that they cannot tell them apart. Most colour blind people are able to see things as clearly as other people but they’re unable to fully ‘see’ red, green, or blue light. Similar problems can arise across the whole colour spectrum affecting all reds, greens, oranges, browns, purples, pinks, and greys. Even black can be confused with dark green or dark blue. There’re different types of colour-blindness and there’re extremely rare cases where people are unable to see any colour at all.
Colour-blindness can go undetected for some time since children will often try to hide their disorder. Children might find food without bright colours as less appetising. The ability to see colour decreases in old age. Simple tasks such as selecting ripe fruit, choosing to clothe, and reading traffic lights can be more challenging. Colour-blindness may also make some educational activities more difficult. Traffic lights always pose challenges since they’ve to be read by the position of the light. Since most lights are vertical, with green on the bottom and red on top, if a light is positioned horizontally, I have to do a quick mental rotation to read it. Reading maps or buying clothes that match colours has always been difficult for me. However, these are relatively minor inconveniences and I have since learnt to adapt.
Being colourblind may make people ineligible for certain jobs in certain countries, like being a pilot, train driver, working in the armed forces, jobs of mixing paint colours, or in which colour perception is important for safety. Colour-vision is important for occupations using telephone or computer networking cabling, as the individual wires inside the cables are colour-coded. Electronic wiring, transformers, resistors, and capacitors are colour-coded as well. Males are more likely to be colourblind than females, as the genes responsible for the most common forms of colour-blindness are on the X chromosome. As females have two X chromosomes, a defect in one is typically compensated for by the other, while males only have one X chromosome. The gene for red-green colour-blindness is said to be transmitted from a colourblind male to all his daughters, who are usually heterozygote carriers and are thus unaffected (thank God, my daughter didn’t inherit it). In turn, a carrier woman has a 50% chance of passing on a mutated X chromosome region to each of her male offspring. The sons of an affected male will not inherit the trait from him, since they receive his Y chromosome and not his (defective) X chromosome. Should an affected male have children with a carrier or colourblind woman, their daughters may be colourblind by inheriting an affected X chromosome from each parent? Diagnosis is typical with the Ishihara colour test; however, a number of other testing methods also exist. There’s no cure for colour-blindness. Special lenses may help people with red-green colour-blindness when under bright conditions. There are also mobile apps that can help people identify colours.
Disclaimer: The views and opinions expressed in this article are the personal opinions of the author. The facts, analysis, assumptions and perspective appearing in the article do not reflect the views of GK.