I grew up on a truck-garden farm where children were paid to pick strawberries and tomatoes. I couldn’t tell red from green; I was forever poor. My siblings – especially my younger sisters – would pick three baskets for each of mine. And I was penalized for the green ones. It must have cost the family a lot of money – the green berries had to be thrown out. No one suspected I might be colour blind. They thought that I was slow and that I wasn’t paying attention. That may have also been true, but that’s an entirely different issue.
Colour blindness is an inherited defect. I don’t know who among my ancestors was similarly afflicted, but it might have been my maternal grandfather who often wore mismatched socks (though that may also have been an entirely different issue). Six percent of the world’s males have the red-green mix-up (but only about 0.5 percent of females), so it is sex-linked – that is, the genetic deficiency is stowed on a mutated X-chromosome. Girls get two X’s (as in XX); boys have an XY set. Girls, then, have a fallback X chromosome which is almost always healthy. I undoubtedly got my bad gene from my mother, though of 6 male heirs to the family throne, I am the only mutant.
Where did this defect originate and how has it lasted – and spread – throughout most of the world’s population? One theory suggests that red-green colour blindness has an evolutionary advantage. Apparently people such as I can see through camouflage better than ordinary people. According to Nature, we can discern 15 shades of khaki. This might have helped us alert the tribe to nearby lions or kittens, though in today’s world it only helps us spot the odd paparazzi in the bushes. I have a different evolutionary theory, though I hasten to add that I’ve never seen it presented elsewhere, so it is probably wrong. People such as I (and 1/16th of the other males) have proven ourselves useless at fruit picking. We are better stalking game and tossing spears. This could reinforce and promote the division of labour which appears to be nearly universal in every tribe on Earth. Send the useless man out to hunt lions. Maybe he won’t come back. But if he does, he has been assisted by that mutated colour insensitivity. Meanwhile the keener-eyed lady cavefolk harvested the non-poisonous red mountain ash berries.
I never stalked lions. Instead, I am a geophysicist who works with maps and charts. Colour blindness presents problems in this field, too. Fortunately, geophysical work- stations can be tuned to display seismic amplitudes in variations of red and blue, or yellow and black, or some other exotic combination that does not range from dark red to dark green. Depth or time maps can be generated in a similar way that also does not discriminate against the colour-impaired.
However, there are a lot of old geological maps using shades of red and green. I’ve encountered many. I get into trouble whenever dark red bleeds into lighter shades which blur to light green and then dark green. I can’t tell them apart. Here is how Steve Dutch of the University of Wisconsin (Greenbay) describes a set of USGS maps:
“Within periods, colors mostly grade from dark at the bottom to light at the top. The middle color is used generically for undivided periods. For sedimentary units, coloring is as uniform as possible across the map, with a few ad-hoc variations for areas where extra subdivisions are required. The principal exception is that I insist granite is pink on a geologic map and other igneous rocks should be red or orange. Igneous and metamorphic rocks are colored using shades that contrast with other rock units, and vary in usage in the Appalachians (Paleozoic), Midcontinent (Precambrian) and far West (mostly Mesozoic and Cenozoic). Each map has its own color legend.”
Did you see what he wrote? “Within [geological] periods, colors mostly grade from dark…to light.” And, “I insist granite is pink…other igneous rocks should be red or orange.” You might as well have the legend printed in Klingon while you’re at it. I am not accusing or blaming Professor Dutch, of course. He is saying exactly what I heard in Geology 101. These are the standard colours of geology, but such colours are impossible for some us. (My worst university mark was a bare pass in my Mineralogy 212 Lab. There was no way that I could cross the polarized light streams through a thin section of plagioclase without killing a Stay-Puff Marshmallow Man.) But it’s not just me and I am not complaining about this First World Problem simply because I am easily irritated. I am writing this for the estimated 6,000 red-green colour blind geologists and geophysicists in the world. I have only mentioned geology/geophysics issues that one finds in a classroom or office – going into the Precambrian bush as a colour blind field geologist opens a whole other can of DEET.
What to do?
- There are advocacy and self-help groups for the colour-impaired. I found this website, We Are Color Blind, and undoubtedly there are others. Unfairly, colour blind folks are not trusted with fighter jets, yet we aren’t compensated for the heartbreak of not being allowed to fly fighter jets. But that’s OK. (In Romania, colour-blind people are not allowed driver’s licences – and that is not OK.) However, we are invariably better looking than average and sometimes that’s compensation enough.
- There are corrective lenses. They even look cool. I may consider the glasses – but they are still rather expensive, although the price came down a lot in the past year. At about $350, maybe I could just rent them one autumn. I could be led around the woodlands so I can share in the ooohs and aaahs that I’ve heard about all my life, but have never experienced. It would also be nice to see the difference at traffic lights, too, instead of just remembering to stop when the light on top is brightest (or is it when the light on the bottom is brightest?).
I once worked in an office with several colour-disabled colleagues. Two were geologists, another was a fellow geophysicist. (He often wore tinted sunglasses at his workstation – now I know why.) I had been at that office for about two years. I had learned small tricks that kept my deficiency from introducing glaring errs of judgement. I remembered which rock horizons were red and green on the maps and I spoke about them knowingly. I kept my disability well-hidden. But the team eventually figured out my problem. Not from my maps, but from my mismatched socks.