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Shark 6th Sense Related to Human Evolution? 308

Posted by ScuttleMonkey from the really-suave-looking-sharks dept.
An anonymous reader writes "Scientists at the University of Florida are claiming that certain genes found in sharks that give them their 'sixth sense' and allow them to detect electrical signals could also be responsible for the development of the head and facial features in humans. From the article: 'The researchers examined embryos of the lesser spotted catshark. Using molecular tests, they found two independent genetic markers of neural crest cells in the sharks' electroreceptors. Neural crest cells are embryonic cells that pinch off early in development to form a variety of structures. In humans, these cells contribute to the formation of facial bones and teeth, among other things.'"
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Shark 6th Sense Related to Human Evolution? More

Shark 6th Sense Related to Human Evolution?

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  • News flash: orthologous structures... (Score:3, Insightful)

    by Anonymous Coward on Wednesday February 08, 2006 @10:15AM (#14669060)
    ...do different things in different organisms. This is not news. It is a study of cellular fate in two different biological contexts of distantly related organisms.
    • ...do different things in different organisms. This is not news. It is a study of cellular fate in two different biological contexts of distantly related organisms.

      Oh, piss off. With that attitude there's no point in doing science at all. It's news to discover the genes and the mechanism and also to find out what structure it was that developed into the organ in question.

  • Wait a minute... (Score:4, Funny)

    by LilGuy ( 150110 ) on Wednesday February 08, 2006 @10:16AM (#14669067)
    Which of these cells pinch off to form friggen laser beams?

  • How many senses do we have? (Score:3, Insightful)

    by SoupIsGoodFood_42 ( 521389 ) on Wednesday February 08, 2006 @10:18AM (#14669079)
    It seems we get a new "sixth sense" every few months. Perhaps it's time to review the whole "five senses" thing so that people stop using "sixth sense" as if it's something special or supernatural?

    • Re:How many senses do we have? (Score:5, Informative)

      by Peter Mork ( 951443 ) <Peter.Mork@gmail.com> on Wednesday February 08, 2006 @10:25AM (#14669137) Homepage
      Let's see, humans have: sight, sound, smell, taste, touch, pressure, deep pain, surface pain, referred pain, hot, cold, static equilibrium, and dynamic equilibrium. Some might even throw in thirst and hunger.

      • Re:How many senses do we have? (Score:5, Funny)

        by qwijibo ( 101731 ) on Wednesday February 08, 2006 @10:31AM (#14669189)
        I can't believe a slashdot poster didn't include spidey in the list.
      • I'd throw in metabolic time at the least. We also have some sense of where all the different parts of us are, though that one may be a derived sense. (From touch, pressure, equilibrium, and memory of our muscle responses.)
      • Pretty much, yeah. I think this whole "people have five senses" thing is silly. We really have nine: sight, sound, taste, touch, smell, heat, pain, balance, and body awareness (or proprioception, my favourite).

        Proprioception is my favourite because of all the fun tricks you can play on it. If you close your eyes and I were to move your arm to some position, this is the sense that you use when you tell me what that position is. Also, there's the well-known trick where you stand in a doorway and press your ar
        • "Also, there's the well-known trick where you stand in a doorway and press your arms against the side for a minute or so, then your arms feel "light" for a while. That works because you confuse this sense."

          I thought this was because you were wearing out one set of muscles that keeps a tension balance in the arms. So, without one set pulling as hard, the other set it still pulling, and your arms feel light.
        • "We really have nine: sight, sound, taste, touch, smell, heat, pain, balance, and body awareness (or proprioception, my favourite)."

          You forgot the sense of style.

      • I'll add electrical sense like the article alludes to, but some may not agree that the sensation of electricity is a separate sense or not.

        This page covers all the ones that the parent mentions. I don't believe he missed one if electricity is ignored or refuted :)

        http://www.sirinet.net/~jgjohnso/senses.html [sirinet.net]

      • It's always pretty interesting when I make dinner.

        I throw something in the oven, and set the timer. In my room, I acn't hear the timer going off, but recently, I've been getting the urge to go check on my food. As soon as I get up there, the timer goes off and the food's done.

        I don't look at the clock or anything, it's kinda weird.

        Maybe it's something like cats and dogs, how they know you should be home at a certain time and will stand at the window looking for you.. *shrug*

    • Re:How many senses do we have? (Score:5, Insightful)

      by pomakis ( 323200 ) <pomakis@pobox.com> on Wednesday February 08, 2006 @10:40AM (#14669253) Homepage
      It seems we get a new "sixth sense" every few months. Perhaps it's time to review the whole "five senses" thing so that people stop using "sixth sense" as if it's something special or supernatural?

      The five senses that humans have are classified as such because they are five distinct ways that we can sense our environment and surroundings. (Some even argue that smell and taste are the same sense because they're both a chemical composition sense.) The ability to sense electrical signals is in every way, shape and form a distinct sense from the five that humans have.

      The universe allows only so many senses, because there are only so many ways that one object can make itself "known" to another object (which is exactly what senses are about). Think about it... there's radiation in the electromagnetic spectrum (sight), compression waves (sound), chemical traces (smell and taste), and actual contact (touch). But nature has a few other communication tricks up its sleeve, and electical signals is one of them. The fact that humans can't sense them doesn't mean that it's supernatural.

      • You seem to be talking in very absolute terms...
        • Scientifically speaking, he's right. We detect one thing when something else hits our bodies. Whether it's a chemical (as in taste), a photon (for sight), or a physical object (for touch), something has to hit us for us to know it's there.

          And there's only so many things that can do that. Electromagnetic fields are one thing that hit us daily and we really don't even know it*, but sharks apparently can. No matter what, there has to be some sort of particle or wave there to actually hit us before we can sense

      • Personally I think balance is pretty darn distinct from the oft-quoted 5. For lay people that don't want to get into all the details (http://www.sirinet.net/~jgjohnso/senses.html [sirinet.net]) balance
        would be the obvious candidate for a popularly recognized "sixth sense"

      • "The five senses that humans have are classified as such because they are five distinct ways that we can sense our environment and surroundings."

        They are classified that way because each of them have big fucking organs smack in the middle of our face.

        We have dozens of other senses that aren't well known because all they are are a few nerves deep inside our body.
        • I think this depends on how you define sense. A lot of the other senses that are often mentioned (hunger, location of our limbs, etc.) are not ways of sensing things about other objects or the environment. They're simply internal feedback mechanisms that help us to function. I think the common definition of the word sense, or at least the one implied by this article, involves the sensing of things that are distinct from the entity doing the sensing.

          Most of our main senses "have big fucking organs smack

          • "Most of our main senses "have big fucking organs smack in the middle of our face" because they're most useful there. Our face is high up, highly pointable, and close to our brain."

            Right. That's why they're there. However, my point is that the reasons that sight, smell, hearing, and taste are the five senses is that the sensing organs are big and obvious.

            Hey, as others mentioned, we have other 'objective' senses such temperature sense, CO2 sense ('stuffy room'), humidity sense, air pressure sense, etc, (
            • The other 'objective' senses that you mentioned are just special subsets of the general senses. Temperature sense - touch; CO2 sense - smell/taste; humidity sense - smell/taste and possibly touch; air pressure sense - sensed by the ear drum using the same mechanism as hearing, and possibly touch. The 'subjective' senses that you mention not senses in the strict sense of the word, because they're internal feedback mechanisms; they don't actually sense anything about the environment. The sense of "orientat
              • "The other 'objective' senses that you mentioned are just special subsets of the general senses. "

                Total bullshit. You're just saying that to give youself some kind of reason to cling to the outdated 'five senses'. Let's go through them:

                "Temperature sense - touch; "

                Wrong. Our pressure-sensitive nerve are totally seperate from our temperature sensing nerves. Different sense altogether.

                "CO2 sense - smell/taste;"

                Tell me, what does CO2 smell/taste like?

                "humidity sense - smell/taste and possibly touch;
    • Erm, this is one sharks have and we don't - they can sense electrical activity in the water. It is one of only six senses we currently count sharks as having, and the other five are identical to human ones.
    • Before you say things like that again, perhaps you might want to review your idea that your layman's simplified idea of biology isn't quite as complete as you might think, and that maybe, just maybe, you shouldn't suggest that biologists review their ideas when you have no idea at all.

      Btw, we have dozens of senses, not 5. You need to very strictly define what a sense is if you want to count them.

  • wtf (Score:3, Funny)

    by bermudatriangleoflov ( 951747 ) on Wednesday February 08, 2006 @10:18AM (#14669082)
    So this is why I was born with a dorsal fin
  • http://www.signonsandiego.com/uniontrib/20060104/n ews_1c04narwhal.html [signonsandiego.com]

    maybe our teeth can pick up radio stations someday :)

  • No mammals? (Score:5, Informative)

    by Jordan Catalano ( 915885 ) on Wednesday February 08, 2006 @10:21AM (#14669104) Homepage
    As they evolved, mammals, reptiles, birds and most fish lost the ability. Today, only sharks and a few other marine species, such as sturgeons and lampreys, can sense electricity.

    The platypus [wikipedia.org] begs to differ...

    • Re:No mammals? (Score:5, Informative)

      by morgdx ( 688154 ) on Wednesday February 08, 2006 @10:30AM (#14669183) Homepage

      Not just the platypus either, but other monotremes (literaly, one hole, I'll leave you to imagine the details) including the Echidna are strongly suspected of having electrosenory receptors.

      A bit more info http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd= Retrieve&db=PubMed&list_uids=9720114&dopt=Abstract [nih.gov] and here http://en.wikipedia.org/wiki/Monotreme [wikipedia.org].

      Maybe this is something else left behind in monotremes from an early link with sharks alongside laying eggs and looking ridiculous out of water.

    • Re:No mammals? (Score:2, Funny)

      by Heem ( 448667 )
      go grab the wires coming out of that socket on the wall over there and tell me you can't sense electricity.
    • Back when there was magic on the Earth, and magicians thru lightning bolts around with abandon... especially this Zeus fellow... it was beneficial to be able to sense electricity.

      Now, only a few people such as electricians would benefit, so no reason for mammals to sense electricity.

      Besides, I like a good shock every now and then. Keeps ya on your toes.
      • I'm not sure about that. Ever walk by a TV (that has no LED) that is turned on, but has a completely black screen? Even though it looks like it's turned off, 99% of the time I (and I'd wager most people) can tell that it's on. Now I've often thought that it must be emitting a sound that though it can't be heard directly, is subconsciously picked up. Still, regardless of how it happens, it's a noticeable phenomenon.
        • Now I've often thought that it must be emitting a sound that though it can't be heard directly, is subconsciously picked up.

          You're hearing the high-pitched whine of the CRT's flyback transformer.

          More interesting, due to age-related changes in your hearing, you probably won't be able to hear it as well in 30 years. I'm 32 now; I can still hear it, but it's much fainter than it was when I was a kid.

  • heh (Score:5, Funny)

    by Moby Cock ( 771358 ) on Wednesday February 08, 2006 @10:24AM (#14669126) Homepage
    A shark's 6th sense.

    "I see soon-to-be dead people"

  • You mispelled... (Score:5, Funny)

    by Anonymous Coward on Wednesday February 08, 2006 @10:24AM (#14669131)
    The researchers examined embryos of the lesser spotted catshark.

    You misspelled laser.

  • People have 6th sense, too (Score:5, Interesting)

    by art6217 ( 757847 ) on Wednesday February 08, 2006 @10:27AM (#14669157)
    Have you ever, while having your eyes closed, felt the position of a pointy object several contimeters distant from you face, especially from your forearm? I did and many people know that feeling. I have no idea whether this is an electrostatic field or what, or if it has anything common with... sharks, but it is probably quite a common phenomenon. I do not really know why I have not seen it described anywhere in the literature.
    • sorry, i have mistaken these two words
    • I've noticed the same. Right over the ridge of my nose. I can tell if someone holds their finger close--but not touching, even with my eyes closed. I've tried the same with others, and they can feel it too. The sensation is almost like a tickle.

    • Re:People have 6th sense, too (Score:5, Interesting)

      by Ironsides ( 739422 ) on Wednesday February 08, 2006 @10:49AM (#14669315) Homepage Journal
      Having done this, there are a few different things that can cause this. Usually, you can feal the radiated heat coming off the person that is near you. Other than that, there is also the air movements that your skin is picking up. This has been done as a scientific experiment before, chalenging blindfolded people to stop as close as they can before walking into a wall. Next time you try this, try wearing a bandana. It confuses the skin sensors and you won't be able to do this.

    • Re:People have 6th sense, too (Score:4, Insightful)

      by patniemeyer ( 444913 ) * <pat@pat.net> on Wednesday February 08, 2006 @11:16AM (#14669501) Homepage
      Remember that you (as a mammal) are covered in tiny hairs. I think you "feel" electrostatic charges because these hairs stand on end.
    • Is it just me, or can other people detect whenever a TV has been turned on (even with no signal)? It's like a faint high-pitched buzz, so I search for the source, and ta-da, the TV was turned on. It's the same with fluorescent lamps.

      Something that strikes me is that the article (or the summary, whatever) says the same cells gave origin to the ears in humans.

      Or maybe i'm just jumping into conclusions.
    • Yes! I've written some details about it on my E2 homepage [everything2.org] (scroll down a little).

      I had the 'forehead sense' quite strong as a younger kid, and it's diminished since. These days I usually get the same feeling during meditation, or intensely focused work (aka 'deep hack mode' :)

  • That missing link... (Score:3, Funny)

    by Tominva1045 ( 587712 ) on Wednesday February 08, 2006 @10:28AM (#14669165)


    In a directly related story, scientists have found THE missing link between sharks and humans in a sub-species. They are calling it entrepreneurius-maximus.

    Offer not valid in NY, Conn., CA, MA, etc.

  • most fish can sense electricity (Score:3, Insightful)

    by peter303 ( 12292 ) on Wednesday February 08, 2006 @10:33AM (#14669207)
    Most fish have some electrical sense, though some may do it better than others. I'd guess this sense was re-invented many times.

    Terrestial animals, including humans, can feel strong gradients in the air before thunderstorms.
    • Terrestial animals, including humans, can feel strong gradients in the air before thunderstorms.

      My personal experience with this is that a very strong field actually causes your fine hairs to react to the field pattern, and you actually feel it as mechanical stimulation of the follicles. No doubt a truly mammoth field gradient would tangibly impact your nervous system to the point of being directly aware of it in some way, but that "hair standing on end" effect is something you can actually see. I was on

  • Humans already have a 6th, 7th, 8th senses. (Score:4, Interesting)

    by Ancient_Hacker ( 751168 ) on Wednesday February 08, 2006 @10:34AM (#14669214)
    6th sense: Your "stuffy room" sensor for excess CO2. 7th sense: Infrared sensors around your lips: Close your eyes. Put your hand three inches from your face. Feel the heat around your lips? 8th sense: Your ears can correlate pressure changes to detect that you're between walls.
  • So there's conclusive evidence that there's an evolutionary link between the development of sharks and lawyers? Or does Intelligent Design explain why some sharks have two legs? Inquiring minds want to know!
  • Now we know where lawyers come from!!!

  • Good news for Creationists (Score:4, Funny)

    by WormholeFiend ( 674934 ) on Wednesday February 08, 2006 @10:44AM (#14669273)
    They'll be happy to know that they haven't evolved from monkeys after all!
  • "Human evolution" is just a theory.

    If you don't believe me, ask the next A&M dropout you meet.
  • The ability to sense electrical signals is useful in aquatic environments because water is so conductive. On land, however, the sense is useless.

    Well, some people have the ability to sense electronic signals in their teeth fillings, which gives a whole new meaning to Bluetooth enabled.
  • found in sharks that give them their 'sixth sense'

    The shark turns out in the end to be dead all along.

  • Neural crest cells (Score:5, Interesting)

    by Graham Clark ( 11925 ) on Wednesday February 08, 2006 @10:55AM (#14669363)
    There's a saying in developmental biology circles that neural crest [wikipedia.org] cells are the only really interestng part of vertebrate embryology. They form (IIRC) the autonomic nervous system, endocrine glands and pigment-producing cells too, as well as the ganglion of the auditory nerve - which is why some animals show a link between colouration and deafness.

  • Sharks? (Score:2, Funny)

    by tak amalak ( 55584 )
    Now they's saying we evolved from sharks? What will those heathens say next?! Pfff, probably that we evolved from bacteria!

  • not much here (Score:5, Informative)

    by tgibbs ( 83782 ) on Wednesday February 08, 2006 @11:35AM (#14669640)
    If I were asked to guess what embryonic tissue shark's electroreceptors came from, my first guess would be neural crest. After all, this is the tissue that gives rise to electrically active tissues like nerve and muscle, which have receptors that do indeed "sense" electrical fields. This is not to allow the animal to sense electrical fields in its environment, but simply the way nerve conduction and muscle contraction work--a change in electrical field (typically produced by a chemically activated ion gate in a membrane) is "sensed" by a voltage-gated ion channel that responds by opening up additional channels, further altering the electric field, which stimulates other voltage-gated ion channels, and so forth. It is easy to see how such a process could be evolutionarily adapted for sensory purposes, just as fish that generate strong electric fields, such as Torpedo (the electric ray) do so with tissues that are evolutionarily derived from muscle.

    So basically, all this is saying is that we and sharks have a common ancestor and as a result share similarities in the development of nervous tissue (which we knew already), and that sharks' electro receptors develop from the tissue that any biologist would identify as the "usual suspect."

  • The other way -- humans "feeling" a shark (Score:5, Interesting)

    by ianscot ( 591483 ) on Wednesday February 08, 2006 @11:36AM (#14669650)
    This headline hit me the wrong way. On Saturday I take the kids on a week-long Hawaii trip, and we've been following a little series of white shark sightings near the islands. It seems like some of the big female whites are out there -- a shark tour guy got out and swam with a "sisterhood"-scale 20-footer whose girth was astonishing in the pictures.

    Anyway, one of the hard-to-pin-down aspects of shark encounters is a "sense" people report having just before they become fully aware of a big shark's presence. This may just be memory colored by the adrenaline rush that came with the encounter -- but it's very commonly reported that, moments before the water starts boiling or whatever, the surfer gets a cold, "something isn't right here" feeling.

    (Which would also be a touch of an evolutionary advantage for the person able to sense it, yeah?)

  • As they evolved, mammals, reptiles, birds and most fish lost the ability. Today, only sharks and a few other marine species, such as sturgeons and lampreys, can sense electricity.

    I beg to differ, as evidenced by the effectiveness of an electrified fence.

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