Sanctuary workers found the so-called Humanzee, 55, dead Saturday in his bedroom at Primarily Primates in Bexar County, the San Antonio Express-News reported. The cause of death was not reported.
Oliver, who was mostly blind, had no teeth and suffered from arthritis in his old age -- and had lived 20 years beyond the average lifespan of 35 years for chimpanzees in captivity, the sanctuary said.
The chimpanzee spent his early years as part of circus shows and in a research lab in Pennsylvania.
Because of his human-like qualities, researchers never included him in studies, the newspaper said.
"For the last part of his life, he got to live in a safe haven -- a non-exploitive, non-commercialized world where he was surrounded by people who love him and in companionship with others of his kind," said Stephen Rene Tello, executive director of the sanctuary.