Do insects feel pain?

[Patrick Foley]

Doug Yanega wrote:

>> What we call our 'pain receptors' are heat receptors, pressure 
>> receptors etc. Insects have lots of similar receptors.
>
>
> Actually, vertebrates do have specific receptors for pain, and special 
> neural pathways to transmit these signals, not shared by insects; if 
> insects feel pain using "similar" receptors, it is not pain as WE 
> experience it, and probably not even very "similar," regardless. This 
> is trivially seen if you compare what happens to a vertebrate if it 
> has a limb removed traumatically versus an insect with a limb 
> similarly removed. Both react violently at the moment of trauma, but 
> they act quite differently once the direct stimulus is gone. A 
> vertebrate writhes in agony for a very long time, and is largely 
> incapacitated simply due to pain. An insect goes about its business, 
> and alters its gait to accommodate the missing limb, but shows very 
> little outward sign of distress.
> I can personally attest to the necessity of pain receptors (as opposed 
> to pressure or temperature receptors) in generating the classic 
> vertebrate reaction, having had a neurological episode which cut off 
> the pain pathways in one of my legs below the knee - I can still feel 
> physical contact, just as sensitively as ever, but I cannot 
> distinguish, say, pressure applied by a pencil tip versus pressure 
> applied by a needle; *neither* is painful to me. I can also tell when 
> something is at a temperature extreme, but not whether it's too hot or 
> too cold, nor does it feel painful (I'm still waiting for an 
> opportunity to win a bar bet by standing on burning coals, on just my 
> left foot, longer than someone else can do the same). Interestingly, I 
> still do have normal reflex responses, but without experiencing the 
> usual pain. Given this (i.e., that the whole "pain" thing in our own 
> system can so easily be thrown off), I find it impossible to believe 
> that insects could feel pain the way we do unless they had EXACTLY the 
> same nervous system, and they clearly do not. I rather expect that 
> they experience stimuli the way my left foot does - pressure and 
> temperature register, and can provoke responses and reflexes, but do 
> not induce *pain*.
>
> Peace,


Doug,

While I agree that there are nerve fibers (alpha and c fibers) and parts 
of the cerebrum dedicated to pain perception, I believe the actual 
receptors are fairly generic neurons. Thus they only respond to extreme 
stimuli.Which usually involves body damage. It is the brain's 
interpretation that is the main determining influence on our experience 
of pain. If transmission are coming down the special fibers, the brain 
interprets the experience as pain. Similarly if you bump your retina you 
see stars. There are no "bump" receptors in your retina.

Patrick

 
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