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sensory cells

Discussion of everything related to the Theory of Evolution.

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sensory cells

Postby scorpion9 » Sat Jul 24, 2010 10:30 pm

hi

could someone explain how did first sensory cell evolved and why where they naturally preferred.
e.g the evolution describes the formation of the eye starting with the formation of a light sensitive cell/patch of cells.

the question is, why should a being have an advantage if they had light sensitive cells. the point is, where did the first sensory input go as it first formed, and what was its purpose.

a clump of cells can develop a patch of light sensitive cells, but they are useless without some kind of "information interpretation by consciousness. and there is a kind of a problem there. this requires a link between a light sensitive cell and a neuron.

lets say id does somehow happen.
some cells develop a capability to sense light. what are the odds that a cell next to them will turn into a neuron? and this neuron...or maybe 100 neurons having enough "consciousness" to understand what light is and take advantage of this extra information.

so in conclusion my question is. how did first sensory cell and first neuron develop. and what kind of advantage could have these cells give to an organism....at a stage where there were few of them.
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Re: sensory cells

Postby jevg » Mon Jul 26, 2010 10:40 pm

The simple answer to your question is that science (scientists) are unable to explain how this would have come about.

The tenor of your question suggests to me that you are asking a question, the answer to which, you already know.

If as I suspect you already know the answer may I ask?
Why the question.
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Re: sensory cells

Postby scorpion9 » Wed Jul 28, 2010 4:45 pm

jevg wrote:The simple answer to your question is that science (scientists) are unable to explain how this would have come about.

The tenor of your question suggests to me that you are asking a question, the answer to which, you already know.

If as I suspect you already know the answer may I ask?
Why the question.




no, i dont know the answer. i had a hunch that there may not be an explanation but i was hoping for an unconfirmed theroy or something that would "seem" to explain it.

i know that my example with the eye development might seem as a "creationist" argument. Well, actually this question rose when i was watching richard dawkins´s video about evolution and i realized that this theory had a premise that there is an "interpreter" for those light sensitive cells, which justifies why they are naturally preferred. But ..... the most interesting part was left out....so i was hoping to find an answer to that.
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Postby Darby » Wed Jul 28, 2010 7:04 pm

You can find light sensitivity in single-celled organisms, as they either orient for photosynthesis (move toward the light) or react to passing shadows (dive or stop moving). So a light-sensitive patch with no imaging power, hooked into a simple reacting movement, still has its uses, but images and processing can be better (but not necessary for all animals).
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Re: sensory cells

Postby Apoptizzle » Wed Jul 28, 2010 7:18 pm

Darby wrote:You can find light sensitivity in single-celled organisms, as they either orient for photosynthesis (move toward the light) or react to passing shadows (dive or stop moving). So a light-sensitive patch with no imaging power, hooked into a simple reacting movement, still has its uses, but images and processing can be better (but not necessary for all animals).


EDIT: Ahhh, I missed the "single-celled" organism part of your post.^^ Oh well, I'll leave my response here anyway...

I believe this still evades the original question, on how the nerve cell would have come about at the same time as the light sensitive patch. Without a "consciousness" being involved, you still need the light sensitive cells to transfer that input into some other cells that are able to react accordingly. How was it hooked to that simple reacting movement upon the development of the light sensitive patch?

My guess would be that all the materials needed are at some point present in the population - like a population of bacteria's antibiotic resistance, even if the antibiotic has never been introduced. The property is in the population, regardless of any use it could possibly serve. You could have a sporadic amount of individuals with light sensitive cells, that aren't doing anything to help them - but the second this mixes with another individuals useless nerve - success! Even if the chances are 1/10^9 or some ridiculous odd, over the course of evolutionary development on Earth - the odds are in favor of it happening at least once.

Just because light sensitive cells, or random nerve placement don't serve a purpose alone, shouldn't mean that those traits - if having arrisen on their own, would just disappear on their own.
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Postby scorpion9 » Wed Jul 28, 2010 9:21 pm

"""but the second this mixes with another individuals useless nerve - success! Even if the chances are 1/10^9 or some ridiculous odd, over the course of evolutionary development on Earth - the odds are in favor of it happening at least once. """

but thats another interesting thing.
suppose u have a population of cells that have the light sensitivity property(which is basically ability to create electricity upon impact with photons)

now, there is another population of cells that developed a primitive capability to conduct electricity.

the problem is....we are talking about populations of cells. just blobs of randomly placed cells that are fighting for survival on a cellular level. even if a light sensitive cell receives a photon and generates electrical impulse and next to it, happens to be a cell with conductor capability, it doesnt give any "symbiotic" advantage. those primitive nerve cells would need another "symbiotic" cells like muscle cells to do something based on the input.

at first we would probably need some kind of "unconscious" hard wired behavior that would bring an advantage over other cells that arent in such symbiotic state.

all this also requires that the cells wouldnt move in relation to each other...And some "master creature" should save this state in the DNA to reproduce the state again(light sensitive cells...next to nerve cell...next to muscle cell) .


i was thinking if the following situation would be biologically possible.
ive read about the bacterial flagellum motor and how it works. i dont understand it 100% for me it seemed that modern bacteria uses difference between electrical charges inside and outside cell wall, this will cause current passing through the parts of the motor and making it rotate. well thats a very simplistic generalization.

could light sensitivity first been introduced in a way that the cell wont use the light as an input of "information" but as an input of "electricity" and create some kind of different charged state inside the cell compared to outside and helping to propel its primitive motor. Basically what im saying that could light sensitivity have been favored not as an information source, but as a source of electricity.....to drive some chemical reactions within the cell.

are there any cellular level reactions that require electricity to function?
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Postby Darby » Sat Jul 31, 2010 7:08 pm

Any true multi-celled system involves communication among the cells. What you see in more advanced systems is some cells becoming specialized to do things that all of the early cells probably could do, using a subset of genes they all have, while other cells specialize in other ways - one system that develops that way is internal communication, with specialized nerve cells.
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