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Humans are a proud bunch. Believing, very mistakenly, that we are the final and greatest product of God's creation.
But our 'perfection' is flawed as compared to some of our fellow lifeforms on this Earth. Does this mean that the universe doesn't revolve around us after all? You decide... |
“it seems that it would take less than half a million years to evolve a good camera eye ... It's no wonder "the" eye has evolved at least 40 times independently around the animal kingdom ... It is a geological blink.” - Richard Dawkins, "River out of Eden" (1995)
We receive a comment from an acquaintance of ours with regards to our previous post on the tesseract. This gentleman is curious on the question of whether a true 3D eye is possible, and on why our eyes have yet to evolve with such an ability.
Certainly it would be more useful to have such an eye. If one were to lose one, he or she would still be able to drive, play tennis, or shoot super-villains from afar as their ability to perceive depth is maintained. Nick Fury would find the last one very helpful.
Before that question can be answered, we have to look back at how our present eyes came to be, and as such how its functions and requirements evolved throughout time.
It all starts with a bang, actually an explosion, the Cambrian explosion. Sometime around 540 million years ago something caused a rapid development of life on Earth. Populating what was before a rather passive, relatively peaceful ocean are now fast-moving, active and more often than not, carnivorous vertebrates.
Just so you’d know, landmasses at the time are still devoid of life with the exception of bacteria, lichens, fungi and microbes. Very much like your average storage room, minus the mountain of cardboard boxes.
Now as they are being actively hunted, life has no choice but to develop ways to either deter their hunters or hide from them; and firstly they have to be able to see them?
The first ‘eyes’ (if we can call them that) are simple light-sensitive receptor cells. These cells are no more than sensors with a simple task – to tell the creature whether it’s dark or light outside. This is a huge step for the creature’s survival as predators (with equally equipped ‘eyes’) are more likely to be active during the day, so telling the difference between light and shadow is a matter of life and death.
Certainly it would be more useful to have such an eye. If one were to lose one, he or she would still be able to drive, play tennis, or shoot super-villains from afar as their ability to perceive depth is maintained. Nick Fury would find the last one very helpful.
Before that question can be answered, we have to look back at how our present eyes came to be, and as such how its functions and requirements evolved throughout time.
It all starts with a bang, actually an explosion, the Cambrian explosion. Sometime around 540 million years ago something caused a rapid development of life on Earth. Populating what was before a rather passive, relatively peaceful ocean are now fast-moving, active and more often than not, carnivorous vertebrates.
Just so you’d know, landmasses at the time are still devoid of life with the exception of bacteria, lichens, fungi and microbes. Very much like your average storage room, minus the mountain of cardboard boxes.
Now as they are being actively hunted, life has no choice but to develop ways to either deter their hunters or hide from them; and firstly they have to be able to see them?
The first ‘eyes’ (if we can call them that) are simple light-sensitive receptor cells. These cells are no more than sensors with a simple task – to tell the creature whether it’s dark or light outside. This is a huge step for the creature’s survival as predators (with equally equipped ‘eyes’) are more likely to be active during the day, so telling the difference between light and shadow is a matter of life and death.
Naturally things won’t remain the same for long; predators too eventually evolve ways to outsmart this early warning system. The next step to this would be a way to discern the direction of light, as even if a prey can swim away from the predator, the latter can tell which direction it is going.
This new development requires only a simple modification, the shape of the photo-sensitive tissue. Such a modification isn’t that hard, and those with shapes that allow it to perform better have a higher chance to survival and pass this trait to their offspring, of which some may develop more effective traits.
Eventually, due to the continuous evolutionary arms race, successive traits develop into functions that fit its environment. A pinhole camera-like eye can focus better, and one that is equipped with a rudimentary lens is a further improvement to that.
Note that I didn’t say ‘better’ due to the nature of evolution through natural selection. From the human perspective ‘better’ means eyes that can focus images from afar, for a mollusk this is overkill.
Maybe a more precise term would be ‘good enough’, as in eyes that are good enough for a particular animal, including humans, to survive in its environs. And this variation even exists within a particular class
of animals, as explained by preeminent evolutionary biologist Professor Richard Dawkins in the video up top.
Now we can answer the questions posed earlier: can our eyes further evolve? Contrary to popular belief, the human eye isn’t perfect as there are both limitations and flaws in its design.
Our eyes cannot, for example, identify anything beyond visible light, rendering it practically useless in the dark. We have a limited binocular field of view, resulting in the failure to discern the distance of objects positioned beside unless we turn our heads. Then there’s our notorious blind spot, due to the flawed structure of our retinas, a handicap unknown to the common octopus. Eight arms and no blind spot? Give them a few million years and they’ll drive circles around Michael Schumacher.
If our eyes were to further evolve naturally, there must be a certain environmental requirement so that only those with a certain trait may be able to survive and/or breed. As there are none, there is no evolutionary pressure that eliminates ‘unfit’ individuals with, for instance, short sightedness or colour blindness; we have learned to function perfectly well despite these limitations through the use of technology. Similarly, there is no pressure to allow those with proto-3D eyes to be the only ones that may survive and/or breed.
It seems that the only way for us to have better eyes is to make them, which brings us to the second question: how does one construct a 3D eye?
An eye is essentially a camera; it takes light in and projects it into a 2D image on the inner surface of the retina, very much like a cinema projector. If we were to project a 3D image instead (and by that I mean actual 3D rather than the nausea-inducing, overpriced abomination we see at cinemas), we have a holographic projector. The question now is how to film a 3D image?
If we look at a cross section of the eye, a lot of the space is made up of the vitreous humor, a translucent, gelatinous fluid which sole function is to maintain the shape of the eye.
What if this space is filled with photoreceptor cells?
We would then face a little problem, filling the vitreous humour with photoreceptors would at best cloud the normally translucent gel (which will get you a blurry image), and at worst stops light from reaching all but the foremost cells (which may render you technically blind); in addition to the fact that these cells are required to be connected to the optic nerve and blood vessels.
Another way is the meta-eye method, having a 3D image projected in the vitreous humour which then is read by at least three internal ‘eyes’ from at least three planes (for length, breadth and depth). If you have a hard time visualizing this, imagine an eyeball with at least three functioning eyeballs inside it.
For now our technology is still limited, but who knows what the future may hold as we progress? And who can imagine what we can see when that day comes?
This new development requires only a simple modification, the shape of the photo-sensitive tissue. Such a modification isn’t that hard, and those with shapes that allow it to perform better have a higher chance to survival and pass this trait to their offspring, of which some may develop more effective traits.
Eventually, due to the continuous evolutionary arms race, successive traits develop into functions that fit its environment. A pinhole camera-like eye can focus better, and one that is equipped with a rudimentary lens is a further improvement to that.
Note that I didn’t say ‘better’ due to the nature of evolution through natural selection. From the human perspective ‘better’ means eyes that can focus images from afar, for a mollusk this is overkill.
Maybe a more precise term would be ‘good enough’, as in eyes that are good enough for a particular animal, including humans, to survive in its environs. And this variation even exists within a particular class
of animals, as explained by preeminent evolutionary biologist Professor Richard Dawkins in the video up top.
Now we can answer the questions posed earlier: can our eyes further evolve? Contrary to popular belief, the human eye isn’t perfect as there are both limitations and flaws in its design.
Our eyes cannot, for example, identify anything beyond visible light, rendering it practically useless in the dark. We have a limited binocular field of view, resulting in the failure to discern the distance of objects positioned beside unless we turn our heads. Then there’s our notorious blind spot, due to the flawed structure of our retinas, a handicap unknown to the common octopus. Eight arms and no blind spot? Give them a few million years and they’ll drive circles around Michael Schumacher.
If our eyes were to further evolve naturally, there must be a certain environmental requirement so that only those with a certain trait may be able to survive and/or breed. As there are none, there is no evolutionary pressure that eliminates ‘unfit’ individuals with, for instance, short sightedness or colour blindness; we have learned to function perfectly well despite these limitations through the use of technology. Similarly, there is no pressure to allow those with proto-3D eyes to be the only ones that may survive and/or breed.
It seems that the only way for us to have better eyes is to make them, which brings us to the second question: how does one construct a 3D eye?
An eye is essentially a camera; it takes light in and projects it into a 2D image on the inner surface of the retina, very much like a cinema projector. If we were to project a 3D image instead (and by that I mean actual 3D rather than the nausea-inducing, overpriced abomination we see at cinemas), we have a holographic projector. The question now is how to film a 3D image?
If we look at a cross section of the eye, a lot of the space is made up of the vitreous humor, a translucent, gelatinous fluid which sole function is to maintain the shape of the eye.
What if this space is filled with photoreceptor cells?
We would then face a little problem, filling the vitreous humour with photoreceptors would at best cloud the normally translucent gel (which will get you a blurry image), and at worst stops light from reaching all but the foremost cells (which may render you technically blind); in addition to the fact that these cells are required to be connected to the optic nerve and blood vessels.
Another way is the meta-eye method, having a 3D image projected in the vitreous humour which then is read by at least three internal ‘eyes’ from at least three planes (for length, breadth and depth). If you have a hard time visualizing this, imagine an eyeball with at least three functioning eyeballs inside it.
For now our technology is still limited, but who knows what the future may hold as we progress? And who can imagine what we can see when that day comes?
Ponder this
Humans are flawed, in many ways then one, how would that enter into our relation with nature? Should we seek to conquer nature, under a mistaken idea that we are 'special', or should we be humbled and appreciate its beauty and majesty?
Without referring to academic resources, can you formulate your own hypotheses on how our other senses (smell, hearing, touch and taste) had evolved?
Discuss
If a complex organ such as the eye can evolve independently in many ways, what other examples of independent evolution are there?
Further readings
Evolution of the eye, at Wikipedia
Cephalopod eye, at Wikipedia
How humans and squid evolved to have the same eyes, at Popular Science
