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This is ALL THINGS CONSIDERED from NPR News. I'm Melissa Block.
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And I'm Audie Cornish. This week, the Fish and Wildlife Service proposed a new rule to protect chimpanzees. Wild chimpanzees are already listed as endangered, and the new rule extends that protection to chimps held in captivity. Nearly half of the chimps here in the U.S. are in research facilities. The change will make it more difficult to use these animals for experiments. As NPR's Rhitu Chatterjee reports, even before this new rule, scientists were already moving away from using chimpanzees.
RHITU CHATTERJEE, BYLINE: Chimpanzee research began in the 1920s. At first, they were used to study psychology and then came the Space Age. In 1961, the U.S. sent the first chimpanzee into space.
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UNIDENTIFIED MAN: And here, some 200 of his fellow chimpanzees are taking part in a program designed to probe the limits of man's endurance.
CHATTERJEE: That's a U.S. Air Force documentary from the period. John Pippin is a cardiologist with the nonprofit Physicians Committee for Responsible Medicine.
JOHN PIPPIN: It's not hard to understand why chimpanzees would have been chosen from a scientific point of view. They do share 98 percent of our DNA.
CHATTERJEE: That's also why around the 1970s, scientists began using chimps to study human diseases and test new drugs and vaccines. Sometimes it worked, but often it didn't. Pippin says the best example is HIV research. He says, in the 1980s, chimps became very popular among scientists trying to develop a vaccine for AIDS.
But as it turned out, chimps don't get AIDS in the same way as humans.
PIPPIN: Two decades of research produced 90 or so candidate vaccines. They have been tested in more than 200 clinical trials and, as you well know, we still don't have an HIV vaccine.
CHATTERJEE: He says our growing knowledge in genetics and genomics explain why the animals have been less useful than previously thought. Their genes may be very similar to ours, but Pippin says how these genes work in the two species is very different.
PIPPIN: How genes are organized and how they're turned on, turned off, how that contributes to diseases and to responses to treatments to diseases is very different between chimpanzees and humans.
CHATTERJEE: On top of it all, animal rights groups and the public are more concerned about using chimps in research. Jeffrey Kahn is a bioethicist at Johns Hopkins University.
JEFFREY KAHN: The question now is being asked in a different way, which is not, is it useful to do research involving chimpanzees, but is it necessary?
CHATTERJEE: In 2011, Kahn looked into that question as the chair of a committee put together by the prestigious Institute of Medicine and found that in most cases, the answer was no because there are alternatives like human cell cultures and other animals. Genetically altered mice, for example, are already used to study human diseases.
They're far from perfect, but new tools are making mice more humanlike.
KAHN: So there's work being done, for instance, at Rockefeller to develop a mouse with, effectively, a humanized liver.
CHATTERJEE: Animal rights groups see the proposed Fish and Wildlife rule as another step toward the end of chimpanzee research. Kathleen Conlee is the vice president of animal research issues at the Humane Society of the United States.
KATHLEEN CONLEE: The cost of using these animals and the availability of other ways of doing this research are leading to an end to their use.
CHATTERJEE: In the very few cases where chimps may still be used, the new rule will require researchers to get a permit and prove that their work will also benefit chimpanzees. The new rule could be finalized within the year, but Conlee says the government needs to figure out what to do with the hundreds of chimpanzees still in research centers around the country. Rhitu Chatterjee, NPR News.