is considerable. Concerned with the burgeoning population of chimpanzees, the stress that the additional animals have created on available facilities, and issues associated with long-term care of captive chimpanzees, NIH asked the National Research Council to study these and related problems. Captive chimpanzees are behaviorally complex and have an average life span of 25 yr for males and 34 yr for females (maximal life spans are 55 yr and 65 yr for males and females, respectively), and their long-term management presents formidable challenges.
The challenges are not simply scientific or financial. The form and substance of this report reflect the fact that questions of science and questions of ethics are often inextricably blended. The very feature that can make the use of chimpanzees critical in biomedical research also entails unique moral questions. On the one hand, chimpanzees constitute a vital scientific resource for research on critical issues of human health, and proposals for their long-term care must not undermine the availability of adequate numbers of them for such research. On the other hand, the complexity of the ethical and scientific challenges follows from the fact that chimpanzees are our closest genetic relative in the animal kingdom. These two factors—scientific use and close genetic relative—cannot be divorced; one cannot appeal to one and ignore the other.
The dilemma of why or whether chimpanzees ought to occupy a special niche in moral deliberations relative to their experimental use cannot be reduced to an either-or situation. It is not simply a question of whether the chimpanzee is "just" another animal or otherwise equal in all respects to a human being. We believe that relevant differences between chimpanzees and humans justify the use of chimpanzees in research that would not be sanctioned if it were proposed to use human subjects. However, the close phylogenetic relationship to humans and complex psychological and social character of chimpanzees that make them more similar to humans than other laboratory animals are also relevant.
The conclusions reached by the authors of this report are based on scientific, financial, and ethical reasoning. Although the scientific and financial arguments might be more understandable to many readers of the report and are sufficient justification by themselves in reaching a decision for some readers, the ethical issues are also important and should be seriously considered, in our opinion. In the traditional sense, ethics requires that decisions be based on clearly articulated core human values—concepts