Scientists and members of the public have been drawn increasingly into a serious debate over the use of animals in research and teaching. At the' core of this interchange is the moral justification for animal use, as well as the quality of life for animals in laboratory environments.
The latter point, quality of life, is important to all scientists-for practical as well as humane reasons. Animals in distress can confound research outcomes. Primatologists are particularly concerned with this issue in light of new federal regulations requiring re searchers to address the "psychological well-being" of captively housed primates. While the overall intent of the new regulations is laudable-we must perceive our subjects as living organisms and not as mere research tools-their implementation at present is fraught with difficulty.
After all, what is quality of life? How do we define and measure psychological well-being in nonhuman primates, particularly when psychologists and psychiatrists have not yet arrived at universal agreement on this topic for our own species? It is tempting to con-dude that human wants and needs are the same as those of nonhuman primates. But this view is presumptuous at the least, and flies in the face of scientific empiricism. We must not make assumptions about what environmental conditions are optimal for any species of captive primate without rigorous, controlled testing of our hypotheses.
The task before us is to understand how primates respond to various environmental factors, and then to specify the range of lab-oratory conditions that might be suitable for housing a given species. This requires first defining and operationalizing typical catch-phrases: "well-being," "optimal environment," "quality of life." Then we must establish effective procedures for evaluating the responses of our animals to environmental change.
The importance of assessing proposed environmental alterations can be demonstrated by our own observations of how several groups of rhesus monkeys responded to two environmental manipulations that we thought at first would promote "psychological well-being." The first of these manipulations involved increasing the pen space of two similarly reared, socially housed groups of monkeys. Each group of four or five adult animals, which included both males and females, was maintained in a floor-to-ceiling pen containing resting shelves and a variety of small manipulable objects. The experiment simply involved adding another unit of exactly the same size to each original pen, thus doubling effective cage space.
We had assumed, of course, that more space would be better, and would result in more active, less tense, less aggressive animals. To our surprise, that did not happen. Although the animals did show a reduction in repetitive stereotypic behaviors such as pacing, we also recorded heightened levels of threat and aggressive behavior. In one group, increased aggression was only temporary and returned to previous levels after a month. The other group, however, did not show a decline in aggressive behavior until their cage was returned to its original size three months later.
Two similar groups of rhesus monkeys thus reacted quite differently to cage enlargement. It might seem paradoxical that captive animals could become more aggressive when provided with more space, but other published reports confirm that this can indeed occur. On the other hand, increasing cage size can also reduce levels of aggression. It's clear that we must evaluate each species and experimental setting independently in order to provide the best conditions for experimental animals.
We tested another kind of environmental enrichment on our monkeys. A set of broad-spectrum fluorescent lamps (Vita-Lites) that had previously been used by another re searcher in our - department for a human study gave us the chance. We decided to in-stall these lights (which, like the Sun, emit ultraviolet as well as visible wavelengths) in one of our colony rooms. The result was an increase in reproductive behavior, which would be a beneficial outcome in some kinds of research. Unfortunately, it was accompanied once again by more aggression, and by increased stress responsivity (measured by urinary cortisol excretion). The latter two effects may well have resulted from the in-crease in reproductive behavior; the breeding season in rhesus monkeys is often associated with heightened tension and aggressiveness.
Although these two manipulations were quite different from one another, we have drawn a few general conclusions. First, similar subjects can respond differently to the same environmental change. Although such variation is not surprising to primatologists, it does complicate the problem of determining optimal housing conditions for a given species. Second, a given manipulation may produce complex consequences that can be viewed by researchers as positive, negative, or both, depending on individual research goals. Finally, the effects of environmental alteration can vary over time, pointing up the need for long-term assessment.
In view of these findings and the conclusions we have drawn from them, are scientists and/or legislators properly prepared to develop a comprehensive set of regulations for ensuring psychological well-being in captive primates? We think not. Our best hope is that the new regulations will lead to accelerated research efforts in this heretofore neglected area.
Novak and Meyer are associate professors in the Department of Psychology, University of Massachusetts, Amherst 01003.