I’ve been on a kind of a sensory perception kick recently. It started with a couple books I read last fall: One about sentient genetically engineered dolphins, and another about spider-people with wide-band visual acuity – classic literature, to be sure. I generally tend to think of my addiction to pulp sci-fi as something to be embarrased about (and probably rightly so), but every once in a while the stuff can get you thinking in a direction that you normally wouldn’t pursue. And this time it was it was about how our senses essentially are the world to us, and it’s fun to consider how different or similar that world can be depending on the character of the sense used to perceive it.
The first crazy thing I learned a few months ago is that echolocation is a learnable skill. Human beings can, and have, learned to effiiciently echolocate. We’re not evolved for it like bats or dolphins, so our biology somewhat constrains our skill, but visually impaired people frequently become competent enough to navigate by sound alone. There are two basic methods of echolocation: passive and active. During passive echolocation ambient sounds are used to convey information about the location of objects, while active echolocation uses sounds made by the echolocator to flesh out a more directed set of information about the environment. Human echolocators tend to use clicks made with the tongue – probably because clicking is an easy noise to make rapidly. Clicking is also a farily high frequency noise, which makes it easier to resolve small and detailed objects. Skilled echolocators have no problem navigating an unfamiliar room or a city street.
It’s easy to think of these people as somehow superhuman, but they’re not – they’ve just picked up a skill that none of us have taken the time to learn. So now I often find myself thinking about all the information that’s lost on me in any given moment. Sitting here right now I just hear the tapping of keys and an idling computer fan, but to the right human being that’s enough information to construct a 3D picture of the entire room. Most of us will remain so wrapped up in our visual world that we can never properly learn to ‘hear’ in the fullest sense. An entire band of wasted information.
So what about sight? Anything interesting going on there? Human beings are for the most part sight-driven creatures, after all. We will even claim that the taste of a food is different if it’s color is changed. But, as it turns out, human beings have a relatively restricted visual perception when compared to much of the animal world. Back in the day (read: geologic era) when ocean dwelling creatures were evolving sight, they adapted to receive the part of the Sun’s electromagnetic spectrum which was most intense in water. Aha, you say, this would be the so-called ‘visual spectrum’ of light – but you would be wrong. You see when the kind of eye that human beings and other vertebrates share evolved, it came with a complement of four color-sensing cells, instead of the three that we now have. One of these (the one that we lack) had a sensitivity fairly high up into what we call the ultraviolet, which would be the colors just beyond blue. So in a sense, human beings are all color blind, and unable to experience the visual world with the fullness that the specs for our biological hardware should allow for. Many species of birds, reptiles, amphibians, and even fish have retained this additional color perception. They live in a world with four primary colors, and can see a color that is a full octave up from red. We can only guess what that would look like.
So how did we humans get put in this sad, three-color state of affairs? Well, it turns out that things could definitely be worse. Humans (and many other primates) are actually freaks twice over when it comes to their color perception. You see, back before mammals had their big break they were mostly hard-working, no-nonsense nocturnal animals, which had no need for such frivolities as being able to see red or ultraviolet light. So without any pressure to redevelop a more colorful visual perception, almost all mammals got on quite happily without any red or UV in their lives. But then when primates evolved, it turned out that being able to see red wasn’t such a bad idea after all, being that there are a lot of tasty fruits that have this particular color. And so primates re-evolved to see red. They are unique among mammals in this way.
But there are still some bugs in the system. For instance in many species of New World monkeys, you only get the full complement of color-sensing cells if you’re female. The guys all end up with some form of colorblindness. I can’t help thinking that it’s just some kind of lucky accident that human beings didn’t end up with the same issue. Can you imagine that world? One where the other gender experiences reality in way that is perceptually different in a completely literal way? Aside from frequent assault by tricky philosophical questions there would also be the very practical mattter that each gender would require a different kind of TV. One equipped with two primary colors, and another with the three we’re used to. His and hers.
Weird right? Well, hold on to your metaphorical butts, because it seems that humans may also be susceptible to a very similar, if slightly less drastic form of this craziness. It’s estimated that between 2-3% of the world’s human female population may have genes that code for an additional color sensor, giving them a total of four. Having just read that, you’re probably imagining all the super-women hiding in plain sight who have the magical ability to see ultraviolet light. Well, unfortunately, no, it’s not quite that cool. This additional kind of cell ends up having a pigment that is most sensitive not to ultraviolet, but to a wavelength somewhere between red and green. However, this is still some pretty crazy stuff. A woman with these genes would be able to differentiate one hundred times the colors that a standard human can, making her universe a noticably richer place to live.
But as cool as that was to read, I had been hoping to learn that there was some way for us humans to regain our verterbrate birthright and see into the ultraviolet range. The sad truth is that we’ll never be able to see a rainbow the way a parakeet can, but thankfully not all hope is lost. Our complete inability to see ultraviolet comes not from the sensitivity of our short-wavelength detection cells, but from the lenses in our eyes. So although the senstivity of our cells in that range is quite low, it’s really our lenses that completely cut off the UV light. In essence, the only way to see UV light is to yank the lenses out of your eyes – But who would do that?
Well, Claude Monet for one. Later in his life Monet developed cataracts in both his eyes, and had his right lens removed in 1923. Using special glasses he was able to paint from the world he saw in that eye, but his work after the surgery changed in character: Everything was bluer. It’s theorized that the post-op Claude Monet was balancing his colors to work in a world that none of us is likely to experience – one which contains that hint of ultraviolet light that our natural eyes deny us the ability to see.
Don’t get me wrong, I love the space shuttle. I was so obsessed with the orbiter as a kid that I once built a model of it out of a toilet paper roll, white tape, and some scraps of Styrofoam. This wasn’t for school or anything; I was just a bored nerdy little kid who was excited about space exploration. So as someone who grew up in the late 80’s / early 90’s, the shuttle system will always embody everything that was cool about NASA when I was a kid. And in a fit of nostalgia and tax return money, I even went down to see the launch of STS-127 in July 2009. I took this picture:
But all good things must come to and end. And to be honest this good thing probably should have ended over a decade ago. When I think about it objectively, the space shuttle really is nothing but a white and black tiled albatross for the US manned space program. I mean, come on! Low Earth Orbit? It’s been 40 years since we put a man on the Moon, and 50 years since Gargarin, we should NOT still be mucking around in LEO. The Obama Administration made the right call; let’s leave this stuff to the contractors. We’ve got bigger fish to fry. Hopefully the end of the shuttle program will mean that NASA finally has enough time and money on it’s hands to build us a rocket powerful enough to push us out of Earth orbit. It’s been four decades already – let’s get back out there.
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