Because the environment is faster then the squrrel has to find stuff for the nest and a safe spot
Most peripheral nerves are nerves outside the brain and the spinal cord, carrying both sensory and motor impulses. The peripheral nervous system is one of the two components of the nervous system, the other part is the central nervous system. Peripheral nerves are classified into motor, sensory and autonomic nerves.
Ageing is the word that describes all that change as the organism evolve and it also includes growth !
This dog already has all the answers