They have been here all along
Before the great beasts, and the first hunter 

Evolution does not have 
           only one engine that drives  
          the change.
Hands and feet and eyes 
  are not necessary for reason. 
A desperate need can drive it; 
      a colony of minds;  
no sound, no light, no smell, 
         no silence.  

Imagine craving
    only individuality but  
        hearing so many voices 
   in your head, 
  always and only.  

It's energy: the you that is you, 
   not flesh and bone, 
 but thought, reason, and memory.  
You do not need the grey stuff, 
  any battery will do.

but there is another way, 
 any wave-theory mathematician can tell you. 

A standing wave can feed itself, like light.  
But it must not change, even the tiniest bit, 
or it will become dissonant and lose its substance.

That is the nature of hell, eternal life but no change.