American animal rights activists rejoiced late last month over a decision by the National Institutes of Health to eliminate a majority of the chimpanzees the agency now employs for scientific research. The primates, which share an estimated 96 to 99.4 percent of DNA with humans, have been employed as a model organism for medicine in the United States since psychobiologist Robert Yerkes bought “Chim” and “Panzee” in 1923. The NIH currently houses 360 chimps, of which 310 will be retired to the federal sanctuary system and 50 will be retained, but not bred, as possible subjects for future work. Said NIH director Francis Collins, “Chimpanzees are very special animals. They are our closest relatives. We believe they deserve special consideration.”
The bioethics of conducting science on animals is based on the framework of “the three Rs” model: replacement, reduction, and refinement. Whenever possible, living systems should be replaced by in vitro (cell culture) models or computer simulations; if animals are absolutely necessary, less “advanced” organisms such as worms or other invertebrates are preferable. An animal study should then strive to reduce the number of individuals it involves while maintaining scientific validity. Good statistical analysis and experimental setups like the repeated measures design can help get the best results from the fewest animals. Finally, the procedures that are conducted should minimize the pain and distress experienced by the subjects. Measures like sedating research subjects before surgery may seem obvious, but stories like those of the unanesthetized baboons in the Experimental Head Injury Laboratory of the University of Pennsylvania should serve as constant reminders to those engaged in animal studies.
In the past, the closeness of chimpanzees to humans has made them a valuable resource for scientists. As the only animal model that can be infected by all strains of hepatitis, chimps were involved in the development of the hepatitis A and B vaccines, and the similarities in their immune systems made chimps a model for the study of HIV/AIDS. The most well-known chimpanzee experiment may be that of “Ham,” whose spaceflight paved the way for the first American astronauts. Yet these uses have been superseded by advances in technology: hepatitis vaccines can be produced in yeast, new HIV/AIDS work has progressed straight from in vitro experiments to human clinical trials, and humans are signing up at $250,000 a head to be shot into space. While future diseases may require chimps as the only viable research model, the present state of science has made them largely unnecessary, and their use therefore less morally defensible.
Recent neurobiology research has also suggested that non-human animals may experience significantly more consciousness than previously thought. The Cambridge Declaration on Consciousness, signed by luminaries such as Stephen Hawking and Francis Crick, states that “the weight of evidence indicates that humans are not unique in possessing the neurological substrates that generate consciousness.” In other words, the similarities of chimpanzees to humans may extend to their feelings of pain, and scientists should ensure that any benefits they gain from chimp research are worth this moral burden.