Chimpanzees in the wild were listed as endangered in 1990, but those in captivity were only listed as threatened, largely to allow trade and use in medical experiments to continue, though many are also privately bred for entertainment.
But the FWS has announced that it found that the Endangered Species Act "does not allow for captive-held animals to be assigned a separate legal status from their wild counterparts."
The FWS proposal came in response to a 2010 request for an endangerment listing submitted by groups such including the Jane Goodall Institute, the Humane Society of the United States, the Association of Zoos and Aquariums.
"Our hope is that this proposal will ignite renewed public interest in the status of chimpanzees in the wild," said FWS Director Dan Ashe.
The FWS proposal comes after a January proposal by the National Institutes of Health calling for new federal rules to restrict medical and behavioral research on the agency’s chimpanzees, noting that the use of apes for research related to neuroscience and infectious diseases is unnecessary.
A co-chairman of the NIH panel, Daniel Geschwind recommended that most apes be retired, saying "there is no compelling reason to maintain a large research population."
The United States is the only nation in the developed world that continues to use apes for research. European countries banned the practice years ago.
"This decision gives me hope that we truly have begun to understand that our attitudes toward treatment of our closest living relatives must change," said Dr. Jane Goodall, best known for her groundbreaking 45-year study of primates in the wild. "I congratulate the U.S. Fish and Wildlife Service for this very important decision."