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Thread: Why do we use sound to communicate?

  1. #61
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    Quote Originally Posted by Noclevername View Post

    I'd say that one ear working is not quite sufficient for directional sound. I have personal experience that losing hearing in one ear makes it much harder to hear clear voices from that side.
    Sorry, let me rephrase it.

    One ear is sufficient to hear a sound coming from any direction.

    =

    One ear is sufficient to hear a sound, if you donít care what direction it comes from.

    If you need to know the direction, I.e. not ďany direction,Ē then you need two ears.
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    Many people have vision problems, which is why we still use sound to communicate. In addition, the sound is indispensable if a person stands on the other side of the wall.

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    Quote Originally Posted by Jimas View Post
    Many people have vision problems, which is why we still use sound to communicate. In addition, the sound is indispensable if a person stands on the other side of the wall.
    Many people have hearing problems which is why we still have eyes.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    I have both vision and hearing problems. I have difficulty seeing things behind me, and I have trouble hearing the difference between an apple and a banana.
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    Note that vertebrates are evolutionally restricted to two eyes. They can chose binocular vision or wider field of monocular vision - we the primates have chosen binocular.

    But even given 3+ eyes, visual light still does not travel around obstacles the way sound does, and depends on external source of light.

    Apes use both calls and gestures. Why did man choose calls and not gestures for language?

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    Quote Originally Posted by chornedsnorkack View Post
    Note that vertebrates are evolutionally restricted to two eyes.
    Iím curious why that is so. Is it because we donít have any structure that could develop into another set of eyes?


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  7. #67
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    Quote Originally Posted by chornedsnorkack View Post

    Apes use both calls and gestures. Why did man choose calls and not gestures for language?
    I think itís a question of emphasis rather than either/or. All people I know use gestures in addition to sounds (Japanese even bow when talking on the phone). My guess is that complex thoughts are easier to express by voice rather than gestures.


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    Quote Originally Posted by chornedsnorkack View Post
    Apes use both calls and gestures. Why did man choose calls and not gestures for language?
    Proto-humans and archaic humans were mostly group hunters of dangerous herd animals in the Ice Age. Under those circumstances taking your eyes off the target to look around is probably a bad way to get fed and a good way to get dead.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by chornedsnorkack View Post
    Note that vertebrates are evolutionally restricted to two eyes.
    Quote Originally Posted by Jens View Post
    I’m curious why that is so. Is it because we don’t have any structure that could develop into another set of eyes?
    We're covered by one: eyes develop from skin. The simplest precursor to an eye is the "eyespot", which is simply a patch of skin that is photoreceptive, like a retina.

    But sprouting another one of those anywhere else on the body would mean making that patch of skin lack some of the specialized traits that make skin skin, so it wouldn't work very well as skin anymore. It would be leaky and an easy spot to get injured and/or infected and let the injury/infection right through to whatever other organ is just behind it. (You might have heard about people dying of infections from ordinary cuts before antibiotics, and had trouble buying it because we've all had hundreds of untreated cuts with no infection or at worst a minor bit of local skin infection that goes away on its own; the missing part in the usual depiction of the danger is that it's really about cuts that are deep enough to get all the way through the skin and into something else inside that's more infection-vulnerable.)

    And even without those issues, an eye as we know it doesn't really work if it's just a spot; it's not much use to us if it doesn't have all the rest of the structure around it like our two eyes do, and that would mean we'd need not only a physical, anatomical place to put it where we don't already have something else that needs to be there (like the scalp, bone, and brain parts at the back of our heads), but also a very long series of separate genetic modifications to rearrange everything else around the new eye to make it work. (Just look at what having eyes nearby did to several different facial bones.) One mutation can happen on its own easily; a whole coordinated set like this won't happen together. The set would need to develop in a series over a long time during which the intermediate stages would all need to have been useful, which they wouldn't be for a species that already has much more developed eyes. (They were useful in our past when we didn't already have what we have now.)

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    Quote Originally Posted by Jens View Post
    I’m curious why that is so. Is it because we don’t have any structure that could develop into another set of eyes?
    Growing and sustaining a complex organ takes up bodily resources. The primitive life who became animal's ancestors might have tried many arrangements of eyes; two apparently emerged as the most successful in competition. Maybe those with multiple eyes to keep up were too "expensive" in biological terms to prosper, and those with only one probably did not get the benefits of either wider or binocular vision.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Thanks to both of you for the responses. I agree they are good reasons for why we "don't" have more than two eyes. What I was really asking though is not why we "don't," but why we are "evolutionarily restricted" to only having two eyes. To me that sounds like there is a stronger reason, as if we couldn't develop them even if it was beneficial.
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    Quote Originally Posted by Jens View Post
    Thanks to both of you for the responses. I agree they are good reasons for why we "don't" have more than two eyes. What I was really asking though is not why we "don't," but why we are "evolutionarily restricted" to only having two eyes. To me that sounds like there is a stronger reason, as if we couldn't develop them even if it was beneficial.
    Evolution doesn't innovate or anticipate anything beneficial, it makes do with whatever mutations come up and sometimes they happen to turn out beneficial. Most do not, and get weeded out by natural selection.

    We could genetically engineer a new eye but we'd also have to redesign the visual centers of the brain to process the added input. As binocular viewers, we would not get much benefit from becoming trinocular. So in order for a third eye to be at all worth it, it would have to provide something extra, like a rear view. We're not wired for that, it would mean a complete redesign of our sensorium.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Noclevername View Post
    Evolution doesn't innovate or anticipate anything beneficial, it makes do with whatever mutations come up and sometimes they happen to turn out beneficial. Most do not, and get weeded out by natural selection.

    We could genetically engineer a new eye but we'd also have to redesign the visual centers of the brain to process the added input. As binocular viewers, we would not get much benefit from becoming trinocular. So in order for a third eye to be at all worth it, it would have to provide something extra, like a rear view. We're not wired for that, it would mean a complete redesign of our sensorium.
    Of course I understand such a simple thing...

    I meant to ask chornedsnorkack what they meant by that...
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    Quote Originally Posted by Jens View Post
    Of course I understand such a simple thing...

    I meant to ask chornedsnorkack what they meant by that...
    OK, I misunderstood the question.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Noclevername View Post
    OK, I misunderstood the question.
    No problem. I wasn't as clear as I should have been.
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    Quote Originally Posted by Noclevername View Post
    As binocular viewers, we would not get much benefit from becoming trinocular. So in order for a third eye to be at all worth it, it would have to provide something extra, like a rear view.
    Thatīs what I considered. Some vertebrates have two eyes that look in different direction, to provide coverage all around, like hares or horses; others have two eyes that provide binocular view in one direction but no view behind, like primates; but vertebrates have to compromise because vertebrates have only two eyes, and cannot have 3 or more eyes to provide view around AND binocular view.

  17. #77
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    Quote Originally Posted by chornedsnorkack View Post
    Thatīs what I considered. Some vertebrates have two eyes that look in different direction, to provide coverage all around, like hares or horses; others have two eyes that provide binocular view in one direction but no view behind, like primates; but vertebrates have to compromise because vertebrates have only two eyes, and cannot have 3 or more eyes to provide view around AND binocular view.
    Chameleons manage pretty well at seeing nearly 360 degrees. Owls can split the difference on looking behind, but only in one direction at once.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    With all mentioned above, sound communication gives us a hand in human exploration missions.
    "This is Ground Control to Major Tom.."
    It is the fastest achievable human-to-human communication nowadays.
    Also in digital traffic processing voice needs hundred times less packetís bulk (i.e. bearer bandwidth and errorless processing). The further sound goes, the more crucial this factor is.
    It is true that all languages have the same bandwidth (but different pitches) and about equal compression rate.

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    It's only mostly true that vertebrates are evolutionarily restricted to 2 eyes. There are some extant lizards and frogs that have a 3rd eye. The 3rd eye, called a pineal organ, is not used for vision but as a sun calibrated compass. Pineal organs were fairly common in some earlier vertebrates. Even weirder, there is at least 1 known example of a vertebrate with 4 eyes, an extinct species of monitor lizard named Saniwa ensiden.

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    Quote Originally Posted by Darrell View Post
    It's only mostly true that vertebrates are evolutionarily restricted to 2 eyes. There are some extant lizards and frogs that have a 3rd eye. The 3rd eye, called a pineal organ, is not used for vision but as a sun calibrated compass. Pineal organs were fairly common in some earlier vertebrates. Even weirder, there is at least 1 known example of a vertebrate with 4 eyes, an extinct species of monitor lizard named Saniwa ensiden.
    A pineal organ is not an eye in the sense that you can resolve an object with it, it's a simple light sensor. You cannot for example, spot prey or predators with one.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    I just wanted to clarify this because I asked the question originally. I realized that vertebrates only have two eyes, but I was wondering why the OP used the word "evolutionarily restricted." I thought perhaps they meant that because of our bilateral symmetry, we cannot develop more eyes, but it seems possible to develop another set of eyes, say above or below the normal two. Is there any reason that we are "restricted" from evolving them? Or does "evolutionarily restricted" simply mean "we don't have them"?
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    Quote Originally Posted by Jens View Post
    I just wanted to clarify this because I asked the question originally. I realized that vertebrates only have two eyes, but I was wondering why the OP used the word "evolutionarily restricted." I thought perhaps they meant that because of our bilateral symmetry, we cannot develop more eyes, but it seems possible to develop another set of eyes, say above or below the normal two. Is there any reason that we are "restricted" from evolving them? Or does "evolutionarily restricted" simply mean "we don't have them"?
    Birds have excellent colour vision with much smaller brains, so brain limitations should not matter, although humans have, I guess, much better visual processing and pattern recognition, perception of small changes and perception / prediction of trajectories.
    You would think 360 degree vision would be a help, but we seem instead to have modelling ability to keep a map of what is behind using memory and sound clues. The evolutionary path to eyes is quite long and the first steps such as light receptors on the back of our necks might not confer much advantage. In terms of communication some animals have developed light generation, especially in dark environments. You can imagine in night hunting, the ability to signal with a voluntary electroluminescence from a hand, say, would be great at moderate distance. For cooperative hunting, which humans are good at. I guess night hunting was dominated by the moon. We did not develop great night vision like some animals, just adequate moonlit vision. And just adequate hearing, not nearly as good as most nocturnal animals. When we did develop light based communication using tools, it was very limited in speed, flags and flares and morse code. This implied bandwidth in modern technology never got started at all, in any animal. The route to radio transmitting and receiving must be just too long for the time we had available!
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
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    Quote Originally Posted by Jens View Post
    I just wanted to clarify this because I asked the question originally. I realized that vertebrates only have two eyes, but I was wondering why the OP used the word "evolutionarily restricted." I thought perhaps they meant that because of our bilateral symmetry, we cannot develop more eyes, but it seems possible to develop another set of eyes, say above or below the normal two. Is there any reason that we are "restricted" from evolving them? Or does "evolutionarily restricted" simply mean "we don't have them"?
    Why would we? Evolution is driven when survival or reproduction are at stake. How would an extra eye benefit a vertebrate species? We already see well enough to survive, and such a radical alteration would probably not make a mate more sexually attractive.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Noclevername View Post
    Why would we? Evolution is driven when survival or reproduction are at stake. How would an extra eye benefit a vertebrate species? We already see well enough to survive, and such a radical alteration would probably not make a mate more sexually attractive.
    I realize you were trying to be helpful, since you quoted my question, but note that that was totally not an answer to what I was asking. I guess maybe you didn't understand what I was asking.
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    Quote Originally Posted by Jens View Post
    I realize you were trying to be helpful, since you quoted my question, but note that that was totally not an answer to what I was asking. I guess maybe you didn't understand what I was asking.
    You asked about evolutionary restrictions. I was trying to describe those restrictions.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Noclevername View Post
    You asked about evolutionary restrictions. I was trying to describe those restrictions.
    What I was asking is, is there a physical restriction that makes it impossible for us to develop more eyes? I realize we don't have more than two eyes, and I realize there is a cost to making them, but what I'm asking is whether there is some physical reason that makes it impossible for us to develop them, in terms of body plan for example.
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    Quote Originally Posted by Jens View Post
    What I was asking is, is there a physical restriction that makes it impossible for us to develop more eyes? I realize we don't have more than two eyes, and I realize there is a cost to making them, but what I'm asking is whether there is some physical reason that makes it impossible for us to develop them, in terms of body plan for example.
    The answer must be physically possible but it is a very long shot. Any person born with for example four eyes from some mutated splitting of the eye development would not have improved vision, so no advantage and a big disadvantage in being seen as a monster. When I described a light sensitive patch on the back, it is a different scenario. In order to progress over many generations toward rear looking eyes, there would have to be some advantage in being light sensitive there. Early aquatic animals seem to have started to detect light that way on the path to evolving eyes. You have probably seen pictures of a mouse with a human ear grafted onto its back by our ability to manipulate cells. Such a mouse would have no survival advantage so very unlikely ( assuming an equivalent genetic mutation) to continue to breed mice with ears on their backs.

    Other animals developed swivelling eyes giving near 360 degree vision, presumably this is an easier evolution path than developing more eyes.

    Once we use our technology to change DNA the rules are very different, we could short circuit the natural selection process. This is happening to change diseases and potentially to “improve” animals and humans. But eyes are no use without nerves and brains, so I guess it will be a long time before anyone attempts extra eyes! Improved eyes with more cones would be easier, I guess.
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

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    Quote Originally Posted by Jens View Post
    What I was asking is, is there a physical restriction that makes it impossible for us to develop more eyes? I realize we don't have more than two eyes, and I realize there is a cost to making them, but what I'm asking is whether there is some physical reason that makes it impossible for us to develop them, in terms of body plan for example.
    There's nothing that makes it physically impossible. But there's also nothing to make it at all likely, either. The odds of success are slim.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Noclevername View Post
    There's nothing that makes it physically impossible.
    Thanks. Thatís what I thought too. I thought it was being argued that it is physically impossible.


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    I am not so sure it is possible? It's definitely not my discipline, but I am not finding documented occurances in a cursory search.

    Craniofacial duplication, diprosopus and even cyclopia? It would seem possible, but if it is, I can't find it?

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