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(io9)   How humans lost our chance at a third eye   (io9.com) divider line 48
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5917 clicks; posted to Geek » on 24 Sep 2012 at 9:28 PM (1 year ago)   |  Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



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2012-09-24 09:28:08 PM
While it might be nice to spot predators, I imagine being able to see behind us all the time (or above us) would lead to some awkward social situations.
 
2012-09-24 09:30:04 PM
images-mediawiki-sites.thefullwiki.org
 
2012-09-24 09:30:51 PM
marsmovies.free.fr

Approves.
 
2012-09-24 09:37:12 PM
www.universeguide.com
 
2012-09-24 09:40:38 PM
The Third Eye would have been blind anyway.
 
2012-09-24 09:42:27 PM

Lsherm: While it might be nice to spot predators, I imagine being able to see behind us all the time (or above us) would lead to some awkward social situations.


Since it's all spitballing at what-if's, I imagine if we had 360(ish) vision, we would stop being human, essentially. Think of how predators would have to work if your prey had what would be essentially omnipresence. Heck, deer and moose have a 300 degree vision ark.

We might be more passive, and less aggressive, since there is no need to actually having to look for things actively, though our back eye wouldn't have binocular vision, obviously.
 
2012-09-24 09:45:10 PM
upload.wikimedia.org

Also useful for melting walls and zapping the Doctor etc.
 
2012-09-24 09:53:49 PM
i296.photobucket.com

You can have your third nostril opened if you make an appointment with the Doktors for "Bob".
 
2012-09-24 09:58:07 PM
ecx.images-amazon.com
 
2012-09-24 10:01:17 PM

slayer199: The Third Eye would have been blind anyway.


Unless there was some way to pry it open
 
2012-09-24 10:01:58 PM

Snapper Carr: slayer199: The Third Eye would have been blind anyway.

Unless there was some way to pry it open


Fark ate my link meh
 
Zel
2012-09-24 10:02:38 PM
The development of the brain is centered on a binocular structure. All the things that make mammal brains different from lizards rely on the shape and patterning of the neurons, starting at your optic nerve and leading into the cerebellum. There's a large chunk of vision processing material which just wouldnt fit a third item.

This animal's third doesn't do precise object recognition, it's only doing light or dark.

Our internal gland can maintain day/night cycles without external influence. This let mammals stay up overnight.
 
2012-09-24 10:02:53 PM
I have often said that if there really was any substance to intelligent design, we would have three arms.

One arm to hold part "a", one arm to hold part "b", and one arm to operate the screwdriver/hammer/ratchet wrench/drill.
 
2012-09-24 10:03:27 PM

AppleOptionEsc: We might be more passive, and less aggressive,


Oh, I don't know. Being able to see your mate's face after you climb off them to go the bathroom might result in a much higher murder rate.
 
2012-09-24 10:04:35 PM
Who cares about a third eye? A third boob, now you're talking.
 
2012-09-24 10:05:44 PM

kevinfra: Who cares about a third eye? A third boob, now you're talking.


*shakes tiny fist*

Here's the pic I had to fetch anyways.....

i291.photobucket.com
 
2012-09-24 10:05:56 PM
Are they not counting the brown eye or dick eye? We missed a 5th eye.
 
2012-09-24 10:07:05 PM
Let me rock you chakra con, chakra con?
 
2012-09-24 10:09:56 PM
It would be something of a waste of resources, since most species can turn their heads using a neck or some similar thing already for other reasons. In the case of humans a lot of our so-called intelligence also derives from or is shaped by binocular vision/depth perception, which isn't benefitted particularly by a third eye (we already have a fixed axis in the form of gravity so there's no need for a purely visual way to add a third coordinate to depth perception).

Also, ocular design stressing field of vision only really benefits species that are purely prey that are designed completely around the idea that they need to run away from basically everything. Omnivorous and hunting species tend to find, again, the balance of resources used to advantage to be rather unfavorable.
 
2012-09-24 10:10:46 PM
images.myfavoritegames.com

Laughs at you puny humans.
 
2012-09-24 10:11:07 PM

NeverUseAbsolutes: I have often said that if there really was any substance to intelligent design, we would have three arms.

One arm to hold part "a", one arm to hold part "b", and one arm to operate the screwdriver/hammer/ratchet wrench/drill.


Or hold down bothyour cousins.
 
2012-09-24 10:11:30 PM
Subby; unless you count your mom's brown eye, right? RIGHT?
 
2012-09-24 10:18:27 PM

jaylectricity: [ecx.images-amazon.com image 300x300]


good album


RedPhoenix122: [images.myfavoritegames.com image 307x230]

Laughs at you puny humans.


his power level is so pathetic, the farmer from the beginning of Dragon Ball Z or Hercules is just as powerful.

/Chiaotzu nooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo
 
2012-09-24 10:28:41 PM
Figured it was because of sharp pointy sticks.
 
2012-09-24 10:29:20 PM
I still want to have a magnet implanted in my left pinky so I can sense electro-magnetic fields... Seriously, I'm planning on doing this next summer when the dude comes to town.
 
2012-09-24 11:02:05 PM
Forgot about this show.

www.nationmaster.com
 
2012-09-24 11:02:50 PM

Thanks for the Meme-ries: kevinfra: Who cares about a third eye? A third boob, now you're talking.

*shakes tiny fist*

Here's the pic I had to fetch anyways.....

[i291.photobucket.com image 420x505]


Fail!

akamai.paramountcomedy.com
 
2012-09-24 11:09:48 PM
It's interesting how this scientific evidence compares to the mystical notion of the Third Eye.
 
2012-09-24 11:24:29 PM
chud.com

"So.... beautiful..."
 
2012-09-24 11:28:07 PM
My fourth grade teacher had a third eye. It was on the back of her head.
 
2012-09-25 12:05:06 AM
Everyone has a third eye ...

It's brown.
 
2012-09-25 12:47:28 AM
More is not always better. We have exactly the right number of eyes we need. Any more would not provide a critical enough evolutionary advantage.

Which is why we don't have 3 eyes now.
 
2012-09-25 01:54:35 AM
The third eye is unremarkable
 
2012-09-25 02:11:47 AM
Pry-ing-op-en-my-third-eye!

/RRRRREAL farkin' high on drugs.
 
2012-09-25 02:49:02 AM
Came for the brown eye, leaving satisfied
 
2012-09-25 03:04:27 AM
If the third eye had developed to pick up infrared images, THEN we'd be talking some serious evolutionary advantage.
 
2012-09-25 03:08:22 AM

Huck And Molly Ziegler: If the third eye had developed to pick up infrared images, THEN we'd be talking some serious evolutionary advantage.


www.chud.com
 
2012-09-25 04:27:42 AM

Virtuoso80: Pry-ing-op-en-my-third-eye!

/RRRRREAL farkin' high on drugs.


Shrouding all the ground around me is this holy crow above me.
Black as holes within a memory and blue as our new second sun.
I stick my hand into his shadow to pull the pieces from the sand.
Which I attempt to reassemble to see just who I might have been.
I do not recognize the vessel,but the eyes seem so familiar.
Like phosphorescent desert buttons singing one familiar song.
 
2012-09-25 08:32:35 AM
I regularly shiat out of my third eye. Dunno what the article is about.
 
2012-09-25 09:16:46 AM

ArcadianRefugee: Huck And Molly Ziegler: If the third eye had developed to pick up infrared images, THEN we'd be talking some serious evolutionary advantage.

[www.chud.com image 850x478]


I have an unabashed love of those cheesy ass movies. The first is still the most entertaining in my book, however.
 
2012-09-25 09:34:04 AM

ArcadianRefugee: Huck And Molly Ziegler: If the third eye had developed to pick up infrared images, THEN we'd be talking some serious evolutionary advantage.

[www.chud.com image 850x478]


I loved how their tongues were penis shaped and their infrared sensors were vagina shaped.
 
2012-09-25 10:24:19 AM
What movie is that from?
 
2012-09-25 10:51:42 AM
"Lizards have a little dot at the top of their heads that is called a "parietal eye." This eye is not as complex or as useful as the two in the front of their heads, but it does react to light. Are they eventually going to have a third eye? No. It's just a vestigial trait"

So some lizards do have a 3rd eye but it's blind?

userserve-ak.last.fm
 
2012-09-25 11:02:33 AM

Grither: What movie is that from?


The ugly thing on the car? Tremors 2. I great(ly cheesy) B movie.
 
2012-09-25 11:45:46 AM

Zel: The development of the brain is centered on a binocular structure. All the things that make mammal brains different from lizards rely on the shape and patterning of the neurons, starting at your optic nerve and leading into the cerebellum. There's a large chunk of vision processing material which just wouldnt fit a third item.

This animal's third doesn't do precise object recognition, it's only doing light or dark.

Our internal gland can maintain day/night cycles without external influence. This let mammals stay up overnight.


This, and frankly we lost any chance at a third functional eye even before we amniotes split from the rest of the Amphibia (sensu lato).

Basically, it looks like evolution of parietal eyes and pineal glands went something like this:

a) Early chordates (a living example being the hagfish) generally have four eyes--in hagfish these are pretty primitive, mostly light/dark sensing.

b) Lampreys and related agnathostome vertebrates also still have four eyes, two of these being the usual eyes (and more derived than hagfish eyes) and two of these being pineal and parietal eyes developing eventually into the pineal and parietal glands in other vertebrates.

c) The major orders of fish (including--of particular note--the lineage that led to tetrapods) seem to have converged two of the "hagfish/lamprey" eyes into a single eye, and in early vertebrates (including ostracoderms, placoderms, and early sarcopterygian fish--and even some early tetrapods) it does seem to have actually been functional, including a specific socket. At any rate, it was shortly after the gnathostome/agnathostome split in vertebrates that was the last time that a fully-functional third eye existed in chordates aside from tuataras.

d) As evolution progressed, almost all orders ended up at the least covering the parietal eye with skin, and it degenerated largely into a light/dark sensing organ in tetrapods sometime after the amniote/lissamphibian split (frogs do still have a parietal eye but far degraded from the basal condition).

e) The one major amniote survivor that seems to have kept the "basal tetrapod condition" re parietal eyes is the tuatara, which has the most developed parietal eye of extant species aside from lampreys--then again, tuataras are quite basal lepidiosaurs and pretty basal for diapsids in general; tuatara parietal eyes include a lens and retina and might even be capable of seeing at least motion if not covered by a thin layer of skin. Squamates (the lizard-snake clade) seem to have a degenerated version capable mostly of light/dark discrimination.

(Alas, I've not been able to find out much on the presence or absence of parietal eyes or parietal glands in testudines--this would actually be interesting, as the general placement of testudines is problematic (to put it mildly) with claims they're diapsids, that they're a "third lineage" along with diapsids and synapsids, or that they're basically derived from "ur-reptiles" after the synapsids went their own way.)

f) Interestingly, the two major clades of animals that developed homeothermy (archosaurs within diapsids and the synapsids including mammals) seem to have lost parietal eyes altogether and the "pineal eye" degenerated long ago into the pineal gland. Encephalisation of homeothermic critters does seem to have a bit to do with this, but one does wonder if homeothermy might well have made the whole concept of parietal eyes for "land-lubber" animals a bit redundant. :D

As for humans not seeing IR/ultraviolet....well, you can blame that Permian extinction event and our little therapsid ancestors going to the trees and only coming out at night to keep from being eaten by those big feathery monsters in the Jurassic and Cretaceous :D

Basically, the basal condition of vertebrates capable of colour vision (sarcopterygid fish on up, and probably crossopterygid fish of at least some clades) is that they're tetrachromates--and yes, that means that they can see partially into the UV and IR ranges. This definitely DOES seem to be the basal condition of tetrapods and early amniotes, and probably even synapsids including early non-mammalian therapsids (yes, before the dinosaurs, therapsids ruled the planet--this is actually Age Of The Synapsids Part Deux).

Diapsids, including archosaurs (including crocodilians and those dinosaurian bats we call birds) and lepidiosaurs, still have this basal condition--they're tetrachromates (some birds might actually be pentachromates) and can see IR and UV light fine. The testudines, wherever the hell they fit in, also see UV/IR as much as we can determine.

Synapsids...well...there's evidence they progressively lost colour vision along the path of evolving from non-mammalian therapsids to mammals; at least some evidence from genetic studies of extant monotremes indicates that early true mammals or mammaliforms may have been trichromatic and then lost trichromancy by the K/T boundary--ever since, almost all mammals have been dicrhomatic (generally having green and blue colour receptors plus rods) with trichromancy slowly and independently re-evolving in three lineages of primates.

(Even in the three primate lineages, there's still...a lot of debugging going on, to put it kindly. Re-evolution of trichromatic vision has occured at least thrice, once in lemurs, once in Old World primates (who are the furthest along) and once in New World primates (howler monkeys); in the case of lemurs it is still very much a sex-linked trait (all males are dichromats, females can be trichromat) and in howler monkeys it is not only apparently not sex-linked but in layman's terms they may be less prone to colour blindness--but it's still new enough in New World primates that the howler monkeys are the first to "get it down". In Old World primates, the trait is still unstable enough and sex-linked-enough that colour blindness and colour perception issues (which are more of a reversion in this case) are not uncommon in human males.)
 
2012-09-25 02:17:16 PM
Came for the Bill Hicks Squeegee the Third Eye reference and am leaving it here for all of you, disappointed in FARK.

Youtube (new window)
 
2012-09-25 11:09:29 PM

Great Porn Dragon: Zel: The development of the brain is centered on a binocular structure. All the things that make mammal brains different from lizards rely on the shape and patterning of the neurons, starting at your optic nerve and leading into the cerebellum. There's a large chunk of vision processing material which just wouldnt fit a third item.

This animal's third doesn't do precise object recognition, it's only doing light or dark.

Our internal gland can maintain day/night cycles without external influence. This let mammals stay up overnight.

This, and frankly we lost any chance at a third functional eye even before we amniotes split from the rest of the Amphibia (sensu lato).

Basically, it looks like evolution of parietal eyes and pineal glands went something like this:
(Words)


Thank you.

//No snark, that was interesting and highly on-topic. Whether original, copy-pasta, or some combination, it made a valuable contribution to the thread, and my day.
 
2012-09-26 12:57:26 AM

NeverUseAbsolutes: I have often said that if there really was any substance to intelligent design, we would have three arms.

One arm to hold part "a", one arm to hold part "b", and one arm to operate the screwdriver/hammer/ratchet wrench/drill.


Abby and Brittany the conjoined twins had a third arm in back but it was removed. Not sure if either could've controlled it or not?
 
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