[Wormtongue]

It seemed to me that the power of the ring was the main (only?) reason for Gollum's long existence. He was a halfling-relative species so he was a mortal being with halfling-length lifespan. I think his memory was shot by the time of his loss of the ring. His only base memories were of evil deeds and greed and murder. Oh, and fish! Aside from his "precious", his pitiful life was wretched survival in brutal conditions alone and unloved. If he was alive for 500 years in this horrid state of being, no wonder he was the way he was. A pitiful shade of a wretched life form, twisted and corrupted by the ring of Sauron.
I wonder if others of his race existed in Middle Earth during the time of the Fellowship. If so, I wonder if Tolkien ever expanded his creation of the people of Smeagol. Lembas for thought....