two eyes, one nose, one mouth (1 Viewer)

[moleculo]

nearly all vertebrates (all?) have the same general construct of sensory organs - two eyes centered in the head, above a centrally located nose, above a centrally located, horizontally opening mouth. Mammals, birds, fish, reptiles, amphibians, everything. This pattern exists in extinct species as well - dinosaurs, pre-historic mammals, etc.

In the history of evolution, why has nothing ever deviated from this pattern?

Certainly, having 360 degree vision would be considered an evolutionary advantage, yet there are no animals that have eyes on the back of their head. Why is everything limited to two eyes? Why are there no high-order animals with 4 eyes, equally spaced around their head?

Why is the mouth always below the eyes? For a surface-feeding fish, wouldn't it make sense for the mouth to be on top of the head? He would be less exposed when eating.

I don't know why this crossed my mind - for all of the variety that evolution has developed over millennia, why has this pattern remained so consistent?

 

[Scoresman]

because God made us that way

 

[skol asylum]

Do you want to dribble your food into your eyes while eating?

 

[belljr]

and then you have the flounder

 

[Brony]

Every land animal has 2 bones in lower appendage, 1 bone in upper appendage, or so I read in Your Inner Fish. The book kind of addresses your question, but we'll always try to be peeling through the onion on why things are the way they are. For instance, some mutations make occur because of the balance of potassium in the embryo, but why some embryos have low potassium is not known.

 

[Doug B]

I don't know why this crossed my mind - for all of the variety that evolution has developed over millennia, why has this pattern remained so consistent?

Don't have time to answer in depth, but a lot of alternate body plans lost out during the Permian extinction.

 

[Dan Lambskin]

Do you want to dribble your food into your eyes while eating?

 

[Jackstraw]

Interesting. Still a small subset of all animals. You have all the insects, invertebrets, microorganisms etc that do not follow these patterns.

 

[gianmarco]

It would have to be a slow, gradual drift. Halfway through your proposed evolutionary change, the mouth and eyes would be at the same level, which would completely suck and be stupid. Thus, it would probably start to just go back to where it was. For all you know, nature already attempted this and just gave up halfway through the process because it realized just HOW ####### STUPID THAT WOULD BE.

 

[Idiot Boxer]

Jellyfish eat through their ######.

 

[moleculo]

and then you have the flounder

yet flounder are born with eyes on both sides. The eye migrates as they mature.

 

[Doug B]

Certainly, having 360 degree vision would be considered an evolutionary advantage, yet there are no animals that have eyes on the back of their head. Why is everything limited to two eyes? Why are there no high-order animals with 4 eyes, equally spaced around their head?

Not necessarily -- vision is "expensive" in terms of the required brain mass and oxygen requirements to support the neurological processing needed. Evolution doesn't work with a plan -- invariably, the "good enough" will carry forward and never develop into the "ideal". So long as the reproduction keeps happening and the genes keep getting spread, "luxury" body parts/senses won't spring up in species.

 

[moleculo]

Jellyfish eat through their ######.

so do starfish.

 

[bostonfred]

Jellyfish eat through their ######.

so do starfish.

and lobbyists

 

[Brony]

Certainly, having 360 degree vision would be considered an evolutionary advantage, yet there are no animals that have eyes on the back of their head. Why is everything limited to two eyes? Why are there no high-order animals with 4 eyes, equally spaced around their head?

Not necessarily -- vision is "expensive" in terms of the required brain mass and oxygen requirements to support the neurological processing needed. Evolution doesn't work with a plan -- invariably, the "good enough" will carry forward and never develop into the "ideal". So long as the reproduction keeps happening and the genes keep getting spread, "luxury" body parts/senses won't spring up in species.

Then why not evolve to 1 eye, or why do some species have evolved to better vision.

BTW, I certainly don't have all the answers, and I certainly believe 100% in evolution, but I sometimes think that evolutionists have to explain everything and put a nice bow on every permutation. I suspect that there is a good amount dumb luck / randomness in some of species differences. Just once, I'd like to hear that ostriches stick their head in the sand cause they're just stupid or that penguins thrive on Antarctica cause a bird 500,000 yrs ago simply got lost.

 

[moleculo]

Certainly, having 360 degree vision would be considered an evolutionary advantage, yet there are no animals that have eyes on the back of their head. Why is everything limited to two eyes? Why are there no high-order animals with 4 eyes, equally spaced around their head?

Not necessarily -- vision is "expensive" in terms of the required brain mass and oxygen requirements to support the neurological processing needed. Evolution doesn't work with a plan -- invariably, the "good enough" will carry forward and never develop into the "ideal". So long as the reproduction keeps happening and the genes keep getting spread, "luxury" body parts/senses won't spring up in species.

don't spiders have like 12 eyes? Like Jackstraw pointed out, there are other constructs in the animal world, but no vertebrates picked up on this.

 

[SaintsInDome2006]

Jellyfish eat through their ######.

So do some people. Some people use it to talk through.

 

[sn0mm1s]

Certainly, having 360 degree vision would be considered an evolutionary advantage, yet there are no animals that have eyes on the back of their head. Why is everything limited to two eyes? Why are there no high-order animals with 4 eyes, equally spaced around their head?

Not necessarily -- vision is "expensive" in terms of the required brain mass and oxygen requirements to support the neurological processing needed. Evolution doesn't work with a plan -- invariably, the "good enough" will carry forward and never develop into the "ideal". So long as the reproduction keeps happening and the genes keep getting spread, "luxury" body parts/senses won't spring up in species.

Then why not evolve to 1 eye, or why do some species have evolved to better vision.

BTW, I certainly don't have all the answers, and I certainly believe 100% in evolution, but I sometimes think that evolutionists have to explain everything and put a nice bow on every permutation. I suspect that there is a good amount dumb luck / randomness in some of species differences. Just once, I'd like to hear that ostriches stick their head in the sand cause they're just stupid or that penguins thrive on Antarctica cause a bird 500,000 yrs ago simply got lost.

Two eyes give binocular vision which is a huge advantage for predators. With one eye you lose your ability to judge distance accurately.

 

[Leroy Hoard]

Do you want to dribble your food into your eyes while eating?

Restaurants would be full of people standing on their heads.

 

[sn0mm1s]

nearly all vertebrates (all?) have the same general construct of sensory organs - two eyes centered in the head, above a centrally located nose, above a centrally located, horizontally opening mouth. Mammals, birds, fish, reptiles, amphibians, everything. This pattern exists in extinct species as well - dinosaurs, pre-historic mammals, etc.

In the history of evolution, why has nothing ever deviated from this pattern?

Certainly, having 360 degree vision would be considered an evolutionary advantage, yet there are no animals that have eyes on the back of their head. Why is everything limited to two eyes? Why are there no high-order animals with 4 eyes, equally spaced around their head?

Why is the mouth always below the eyes? For a surface-feeding fish, wouldn't it make sense for the mouth to be on top of the head? He would be less exposed when eating.

I don't know why this crossed my mind - for all of the variety that evolution has developed over millennia, why has this pattern remained so consistent?

There haven't been any major deviations because the evolutionary pressure isn't there - that is the simple answer. The design works very well.

Some animals, like horses, have nearly 360 degree vision with only two eyes.

As for fish - is there a surface only feeding fish?

 

[SaintsInDome2006]

Certainly, having 360 degree vision would be considered an evolutionary advantage, yet there are no animals that have eyes on the back of their head. Why is everything limited to two eyes? Why are there no high-order animals with 4 eyes, equally spaced around their head?

Not necessarily -- vision is "expensive" in terms of the required brain mass and oxygen requirements to support the neurological processing needed. Evolution doesn't work with a plan -- invariably, the "good enough" will carry forward and never develop into the "ideal". So long as the reproduction keeps happening and the genes keep getting spread, "luxury" body parts/senses won't spring up in species.

don't spiders have like 12 eyes? Like Jackstraw pointed out, there are other constructs in the animal world, but no vertebrates picked up on this.

I think the point about the fish and the fact that we may all ultimately be descended from amphibians who clambered out of the muck of the sea may be it.

I will also point that there have been 5 major, worldwide extinctions over the history of the world, and what we see now is just a sliver of what has come before.

I think one trick is that you are limiting it to vertebrates, once you do that you're basically relying on a linear skeletal structure that pretty much lines up as a left and right (limbs, eyes) and a middle (alimentary, digestion, breathing (butt, organs, nose, mouth)).

 

[Bucky86]

Can you imagine if women had two mouths?AMIRITE??

 

[gianmarco]

Can you imagine if women had two mouths?AMIRITE??

And FOUR EYES!!!

 

[Doug B]

As for fish - is there a surface only feeding fish?

Besides, for surface-feeding fish (yes, they exist) the ability swim "vertically" so that their mouth picks up the morsels while their body is below them works just fine and allowed plenty of reproduction. Without a clear reproductive advantage to another scheme, that other scheme won't win out over the existing biologically successful scheme.

 

[Doug B]

Like Jackstraw pointed out, there are other constructs in the animal world, but no vertebrates picked up on this.

Vertebrates came about basically as riffs on a single theme, as it were (as SaintsInDone points out).

Evolutional, as a blind process, doesn't really "care" about what's conceivable, or what could be "engineered better". If a body type is good enough to pass genes on, it stays.

 

[Doug B]

... why do some species have evolved to better vision.

Not all species face the same reproductive pressures. There's no reason at all to expect that all species that have vision to all have developed as the same type and to the same degree.

 

[sn0mm1s]

As for fish - is there a surface only feeding fish?

Besides, for surface-feeding fish (yes, they exist) the ability swim "vertically" so that their mouth picks up the morsels while their body is below them works just fine and allowed plenty of reproduction. Without a clear reproductive advantage to another scheme, that other scheme won't win out over the existing biologically successful scheme.

I know that there are fish that feed on the surface... but exclusively? That seems like a rather limiting form of feeding since most fish can feed on the surface - and most food sources sink. It isn't like they are filling some niche that other fish can't.

 

[Bull Dozier]

Certainly, having 360 degree vision would be considered an evolutionary advantage, yet there are no animals that have eyes on the back of their head. Why is everything limited to two eyes? Why are there no high-order animals with 4 eyes, equally spaced around their head?

Not necessarily -- vision is "expensive" in terms of the required brain mass and oxygen requirements to support the neurological processing needed. Evolution doesn't work with a plan -- invariably, the "good enough" will carry forward and never develop into the "ideal". So long as the reproduction keeps happening and the genes keep getting spread, "luxury" body parts/senses won't spring up in species.

Then why not evolve to 1 eye, or why do some species have evolved to better vision.

BTW, I certainly don't have all the answers, and I certainly believe 100% in evolution, but I sometimes think that evolutionists have to explain everything and put a nice bow on every permutation. I suspect that there is a good amount dumb luck / randomness in some of species differences. Just once, I'd like to hear that ostriches stick their head in the sand cause they're just stupid or that penguins thrive on Antarctica cause a bird 500,000 yrs ago simply got lost.

Two eyes give binocular vision which is a huge advantage for predators. With one eye you lose your ability to judge distance accurately.

Predators generally have both eyes at the front of their head, giving them better binocular vision to help in hunting. Prey generally/often have wider set eyes, nearer the side of their head to give them a wider range of vision.

While multiple eyes have not succeeded evolutionarily speaking, different placement of the eyes leading to different vision advantages have evolved.

 

[Doug B]

I know that there are fish that feed on the surface... but exclusively?

Probably not exclusively, you're right. Fish are pretty opportunistic.

 

[Gr00vus]

nearly all vertebrates (all?) have the same general construct of sensory organs - two eyes centered in the head, above a centrally located nose, above a centrally located, horizontally opening mouth. Mammals, birds, fish, reptiles, amphibians, everything. This pattern exists in extinct species as well - dinosaurs, pre-historic mammals, etc.

In the history of evolution, why has nothing ever deviated from this pattern?

Certainly, having 360 degree vision would be considered an evolutionary advantage, yet there are no animals that have eyes on the back of their head. Why is everything limited to two eyes? Why are there no high-order animals with 4 eyes, equally spaced around their head?

Why is the mouth always below the eyes? For a surface-feeding fish, wouldn't it make sense for the mouth to be on top of the head? He would be less exposed when eating.

I don't know why this crossed my mind - for all of the variety that evolution has developed over millennia, why has this pattern remained so consistent?

Whales, dolphins, porpoises, etc. all have their "nose" above their eyes at this point, and evolved to be that way from your conventional layout.

ETA: Hammerhead sharks have a unique sensory layout too. Their eyes lay almost on the same horizontal plane as their mouths.

 

[bostonfred]

Can you imagine if women had two mouths?AMIRITE??

And FOUR EYES!!!

foureyeddoubletalkingsluts.com is already taken but you can still get .net .gover and .sexy

 

[moleculo]

Can you imagine if women had two mouths?AMIRITE??

I can't get my wife to shut up as it is.

 

[moleculo]

nearly all vertebrates (all?) have the same general construct of sensory organs - two eyes centered in the head, above a centrally located nose, above a centrally located, horizontally opening mouth. Mammals, birds, fish, reptiles, amphibians, everything. This pattern exists in extinct species as well - dinosaurs, pre-historic mammals, etc.

In the history of evolution, why has nothing ever deviated from this pattern?

Certainly, having 360 degree vision would be considered an evolutionary advantage, yet there are no animals that have eyes on the back of their head. Why is everything limited to two eyes? Why are there no high-order animals with 4 eyes, equally spaced around their head?

Why is the mouth always below the eyes? For a surface-feeding fish, wouldn't it make sense for the mouth to be on top of the head? He would be less exposed when eating.

I don't know why this crossed my mind - for all of the variety that evolution has developed over millennia, why has this pattern remained so consistent?

Whales, dolphins, porpoises, etc. all have their "nose" above their eyes at this point, and evolved to be that way from your conventional layout.

ETA: Hammerhead sharks have a unique sensory layout too. Their eyes lay almost on the same horizontal plane as their mouths.

good point.