You’ve almost certainly heard about red-green color blindness. It’s terribly common – in occurs in ~8% of European men. That is a surprisingly high frequency for a genetic problem, but the fundamental cause is a weirdly high mutation rate, due to the fact that the genes for the red and green cone pigments are right next to each other on the X chromosome and often get scrambled in recombination. Even in this case, though, natural selection matters: deuteranopia is less common outside of Europe, sometimes far less common. About 5% of men in China have it, while about 1% of Pygmies do. The suspicion is that it matters less among farming peoples than in hunter gatherers, and thus is more common in people who have been farming longer, least common in people who are still foragers.
There is an interesting riff on this: some of the scrambled versions of the red and green genes still work, but have slightly nonstandard absorption spectra. So there are a number of slightly different green and red genes – and women, with two X chromosomes, can have four different color sensors, instead of the standard three. There is something similar in New World monkeys, where males have two working cone pigments and females often have three.
Usually the brain wiring doesn’t seem to support four color vision in women who are tetrachromats, but at least one case exists. Most people can distinguish about 1 million different color, but she can probably distinguish 100 million. She can see things no else can see, without taking a potion.
In principle one could push this farther by putting contact lenses with different filters in each eye, so that the left eye saw the bottom half of red and the right eye the top half: ordinary people could in principle distinguish six colors, while that tetrachromat lady could distinguish eight. But it might screw up your depth perception, you’d likely get a headache, and, as my real analysis prof said (Wolfgang Haken), four colors suffice.
You probably know of color-blind men who have someone else help them pick out clothes: they can’t tell, but most other people can. The lady who is a working tetrachromat could give you better advice on how things really look, but she’s one of the very few people who could appreciate the effect. But doesn’t that make it even classier?
I mean, audiophiles have been known to shell out lots of money for highly linear audio systems – when they can’t hear the difference. Personally, I used to subscribe to Low Fidelity, because I loved those analytical articles about taping a quarter on the tone arm, recording AM music during a thunderstorm, and saving audio system money by repeatedly hitting a roll of caps with a hammer on the Fourth – but not everyone is like me.
The story is similar, but more complicated, with olfactory receptors. There are about 400 working olfactory receptors in humans, but many of them have multiple versions, including pseudogenes – rather like red-green color blindness, only there are 400 detectors involved instead of 3, and 70 of them work in some people but not everyone. And, like color blindness, the frequency of these non-working versions varies between populations. In those olfactory genes that have working and nonworking versions, Pygmies seem to have higher frequencies of the working versions than Europeans do, just as they are less likely to be color blind. Probably the sense of smell works better in the rain forest (moist air) and it may be that the ability to recognize certain specific scents, such as that of a lion hiding in the bushes nearby, has survival value.
There are so many possible combinations of working and nonworking olfactory genes that very few people, maybe no-one other than identical twins, share the same set of smell receptors. This explains otherwise inconceivable things, such as people who like broccoli. They taste a different world.
If Pygmies do have a significantly higher fraction of working olfactory genes, probably some Pygmies have a better sense of smell than any European. It might be that the average Pygmy has a better sense of smell than any European. And this suggests a new career path for the Pygmy race.
Right now Pygmies are taking it in the shorts. They are often enslaved, always discriminated against, sometimes eaten. They need to find a new way. If I’m right, their natural new niche is as super-sommeliers. They’ll know more about wine than you ever will: you’ll never be able to taste what they taste. Reminds me of a televised Beethoven concert at Wolf Trap where an interpreter was signing for the hearing-impaired: I figure he was saying “This shit is great, but you’ll never know, because you’re fucking deaf!”
Once they learn the patter and the necessary arrogance – once we teach them to look down on customers while looking up at them – they’ll be a shoo-in. It will be as big a success as Neanderthal gaming. Every five-star restaurant will have one.