Do insects feel pain?

Doug Yanega dyanega at ucr.edu
Mon May 23 13:12:33 EDT 2005


>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 Yanega        Dept. of Entomology         Entomology Research Museum
Univ. of California - Riverside, Riverside, CA 92521-0314
phone: (951) 827-4315 (standard disclaimer: opinions are mine, not UCR's)
              http://cache.ucr.edu/~heraty/yanega.html
   "There are some enterprises in which a careful disorderliness
         is the true method" - Herman Melville, Moby Dick, Chap. 82

 
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