What is wrong with this statement (cns)?

D

Datura

surrender to nothing
Registered Senior Member
Why does sensory perception have to end at the level of having a nervous system? There's actually evidence out that suggests that microbes can detect environmental changes:

http://www.wired.com/wired/archive/11.04/quorum.html

here's a little excerpt from the article:

"Bassler and other researchers have determined that bacteria communicate using molecules comparable to pheromones. By tapping into this cell-to-cell network, microbes are able to collectively track changes in their environment, conspire with their own species, build mutually beneficial alliances with other types of bacteria, gain advantages over competitors, and communicate with their hosts - the sort of collective strategizing typically ascribed to bees, ants, and people, not to bacteria."


If microbes can collectively track changes in their environment, then why can't they perceive things? Feel things? The same goes for plants and sponges.

Granted, the perceptions of these organisms would be on a level that we can't even imagine, because there's no central nervous system.
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So is this person right or wrong? Has it been proven without a doubt by science that a brain must be in place in order for physical sensation to occur?
 
must [a brain] be in place in order for physical sensation to occur?
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Not at all. Part of fitting the criterion for being alive is the ability to percieve environmental changes. If you cannot sense changes in your environment, then there is no way you can change to fit your environment, an hence will perish.

Even trees respond to the envrionment. When it gets cold, they begin to flower, when the ratio of light to dark changes, they begin to drop leaves, when animals nibble on birch, the trees begin to grow bad asting nodes at the places where they were nibbled.
 
When you burn yourself and retract your hand, it's actually just a reflex. The signal to pull out comes from your spinal column before your brain has anything to do with it.
 
You're talking about humans though. My question concerns living things without nerves.
 
Our reflex includes more cells, but it is still 'reflex,' as there is no rational brain making the decision, just cellular reflex.

Nerves are specialized cells that let other cells know they are being damaged, so the organism can move away from the pain. Specialized cells for detecting and reacting to stimuli are faster and more efficient than all the cells detecting them.

There is no room in single celled organisms for nerves, so other structures take control. Obviously, as a protist will swim away from damaging salt, we know they can detect threats in their environment. They just do it differently than multicellular organisms.

Is it the same level of feeling? I have no idea, but I don't think it really matters. Most people assume that when animals experience pain, it's less important than human pain. I'd say that all pain is really the same (as it serves the same purpose), and there's not much difference between animals or bacteria or humans experiencing pain.
 
It may not matter from a scientific perspective, but I would like to know.

Is there a link someone can provide that says whether or not that which lacks nerves can feel pain? Surely someone has an answer...
 
Datura said:
It may not matter from a scientific perspective, but I would like to know.

Is there a link someone can provide that says whether or not that which lacks nerves can feel pain? Surely someone has an answer...
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It's been well documented that bacteria will recoil from certain stimuli and be attracted to others, such as cAMP levels. This is all mediated by simple signal transduction within the cell. But to argue that these bacteria actually <i>feel</i> hungry, or </i>feel</i> pain? I doubt it.

Datura said:
Granted, the perceptions of these organisms would be on a level that we can't even imagine, because there's no central nervous system.
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It's a different type of perception, as it's all mediated by signal transduction. I would say it's more like reflex. As for feeling pain, I doubt it. Actual sensations such as pain are mediated by certain nerves - but I may be incorrect, as nerve physiology is not my field of study.
 
When you are asleep, hypnotised, under medication or in meditation, your body can react to some pain stimulii, but do you 'feel pain' if you don't remember it later?

Unfortunatly, this area of study requires consciousness in order to determine if the reaction observed is pain or simply reaction. Until we are able to understand the consciousness level of other living things, it will be impossible to know for sure if they feel pain, or simply react.
Having dealt closely with trees for a number of year in my Bonsai business, I can say that certain species of trees seem to reaction to physical damage more dramatically than any reasonable reaction would entail. Some to the point where the reaction is so severe that it endangers the life of the plant - I guess it very much like shock in people.
 
We only refer to sensory perception in organisms with a CNS because that's how we've defined it. Each cell in a multi-cellular organism must also have the ability to react to changes in its environment, or the entire cell social network of the would break down. But I think where we really draw the line between reflexes and senses, in terms of influencing behaviour, is at the fact that the latter allows for learning; you might move your hand away from a flame because of reflexes, but it's the slower messages that make up the sensation of touch that allow you to learn that sticking your hand in a flame is a decidedly bad idea.
 
But you can train flatworms to react to light over time via either positive or negative feedback. Pavlov's dog and all that.
Where does learning end and training begin? Are they truely different?
 
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