Chimpanzee Toni celebrated his 50th birthday at the Hellabrunn Zoo in Munich on Nov. 22, 2011.
This week, the U.S. Fish and Wildlife Service proposed a new rule that would extend "endangered species" protections to chimpanzees held in captivity. Nearly half of all the chimps in the U.S. live in research facilities, and the regulation changes would make it more difficult to use these animals in medical experiments.
But don't expect an outcry among most scientists. In the past decade or so, "there has been a significant shift away from using chimpanzees in research," says Kathleen Conlee, the vice president of animal research issues at the Humane Society of the United States.
Scientists first became interested in studying chimps in the 1920s to gain insights into primate psychology — including, they hoped, the psychology of humans.
And then came the Space Age. In 1961, the U.S. sent a chimpanzee named Ham into space, and soon the primates became the animal of choice for getting a sense of how humans might fare in rocket flights beyond Earth's atmosphere.
It wasn't until around the 1970s that chimps became a popular model for studying some infectious diseases — and for testing new drugs and vaccines.
"It's not hard to understand why chimpanzees would have been chosen from a scientific point of view," says John Pippin, a cardiologist who is with the nonprofit Physicians Committee for Responsible Medicine. "They do share 98 percent of our DNA."
Sometimes chimpanzees did lead to important breakthroughs, researchers say, for example in understanding and treating hepatitis B and C. But more often, as in HIV research, those chimp studies didn't reveal much.
In the 1980s, chimps became very popular among scientists trying to develop a vaccine for AIDS. But as it turned out, Pippin says, chimps don't get AIDS in the same way as humans. "Two decades of research produced 90 or so candidate vaccines," he says. "They have been tested in more than 200 clinical trials and, as you know, we still don't have an HIV vaccine."
Our growing knowledge in genetics and genomics help explain why the animals have been less useful than previously thought. Their genes may be very similar to ours, Pippin says, but "how genes are organized, and how they're turned on, turned off, how they contribute to diseases and to responses to treatment [for] diseases is very different between chimpanzees and humans."
And, over time, animal rights groups and the public seem to have become more concerned about using chimps in research. "The question now is being asked in a different way," says Jeffrey Kahn, a bioethicist at Johns Hopkins University. "Not, 'Is it useful to do research involving chimpanzees?' But [rather] 'is it necessary?' "
In 2011, Kahn was chairman of an Institute of Medicine committee that looked into that question. The committee found that the answer was no, because there are alternatives such as human-cell cultures and other animals. Genetically altered mice, for example are already used to study human diseases. Rodents aren't a perfect proxy for humans, but new genetic tools are making mice more humanlike in the way they respond to microbes and drugs.
"There's work being done, for instance, at the Rockefeller [University] to develop a mouse with a humanized liver," says Kahn. Such mice, he says, would make a great model for studying human diseases like hepatitis.
Animal-rights groups see the proposed Fish and Wildlife rule as a move in the right direction. "The cost of using these animals and the availability of other ways of doing this research are leading to an end of their use," says Conlee, the Humane Society vice president.
In the very few cases where scientists feel they must rely on chimps, the new rule would require a permit. And the researchers would need to prove that their work also benefits chimpanzees.
The agency is taking public comments on the proposed rule until Aug. 12 and hopes to finalize the regulation within a year.
Though chimp research is winding down, Conlee says, the federal government has yet to figure out what to do with the hundreds of chimpanzees no longer needed that still live in research centers around the country.