For the most part, nonhuman primates are research subjects because they are so similar to humans, and the principal reason for this similarity is simple: humans *are* primates. Current ideas are that the first primates appeared more than 60 million years ago. In contrast, the common ancestor of humans and African apes lived only about 5-8 million years ago; so, for more than 50 million years, humans and the African apes have shared primate ancestry. Shared ancestry is a major reason why human and nonhuman primates have many characteristics in common — tool use, long-lasting social relationships, and complex communication systems. By learning about nonhuman primates we may come to learn more about ourselves. For example, humans walk upright, on two limbs — we are bipedal. Why might humans have evolved to be bipedal, when the vast majority of nonhuman primates are quadrupedal? Individuals of certain nonhuman primate species, however, are bipedal for some activities. By studying those species of nonhuman primates that are occasionally bipedal, and discovering the circumstances in which they display bipedality, we may gain some understanding of the factors that promoted the evolution of bipedality in humans.
Human and nonhuman primates also share physiological characteristics. For example, the way in which the brains of rhesus monkeys and humans are organized is similar. One brain area that has been studied extensively is the visual system. Neuroanatomical studies of the nonhuman primate brain have been extremely useful in helping us to understand how the human brain functions and how we see. In this way, nonhuman primates serve as models of particular processes that would be extremely difficult or impossible to study in humans. Study of nonhuman primates has also contributed to our understanding of basic biological phenomena such as reproduction; to better understanding of diseases such as AIDS; and to the development of drugs, treatments, and vaccines for the promotion of better health for human and nonhuman primate alike. In fact, research conducted with nonhuman primates has contributed to Nobel-prize-winning research: development of yellow fever vaccine (1951); culturing of poliovirus that ultimately led to a polio vaccine (1954); and the significant discoveries in visual processing in the brain (1981) (reference: R.W. Leader & D. Stark, 1987, The importance of animals in biomedical research. Perspectives in Biology and Medicine, vol. 30, no. 4, pp. 470-485; see also The Foundation for Biomedical Research, The payoff from animal research).
Of course, nonhuman primates are also studied because they are fascinating animals. They live in a wide range of habitats, and show many interesting differences in behavior and life styles. For example, in some species like squirrel monkeys, many adult males and many adult females live together the year round in a troop that also contains infants and juvenile animals. In other species, like titi monkeys that live in the same area as squirrel monkeys, a single adult male and a single adult female live together with their offspring. What might account for the differences between these two types of social systems? Are there differences in psychological characteristics between squirrel and titi monkeys that might be related to their different social systems? Male titi monkeys appear to exhibit behavior that looks very much like jealousy, but male squirrel monkeys do not. Why is that?
As you can see, there are many kinds of ‘primate research’, including field observations of undisturbed wild primates, behavioral observations of animals in captive colonies, experimental behavioral and physiological research, biomedical research, and more. For further information on many types of research involving nonhuman primates, see F. King, C. Yarbrough, D. Anderson, T. Gordon, and K. Gould, 1988. Primates. Science, 1988, vol. 240, pages 1475-1482.
According to the Fiscal Year 2006 Animal Welfare Enforcement report, 1,012,713 warm-blooded animals were used in research, testing, teaching, or experimentation. This figure does not cover laboratory rats and mice, and farm animals used exclusively in agricultural research. Of these, 62,315 primates (6.15% of the total) were used. Two points should be made. First, the vast majority of animals used in research are laboratory rats and mice. In 1995, researchers at Tufts University Center for Animals and Public Policy estimated that 14-21 million animals were used in American laboratories in 1992. In 1986, the U.S. Congress Office of Technology Assessment reported that that its best estimate was 17-22 million. The difference between the 1.01 million and the estimated 14-22 million numbers mostly reflects rats and mice (and birds). Second, individual animals are ‘used’ more than once, in most cases. That is, many, if not most, of the 62,315 primates studied in 2006 were probably also studied in 2005, and again in 2007. These numbers refer just to captive animals; unfortunately, there is no estimate available for the number studied in their natural habitat. (Reference here).
In laboratories, the most common species studied are Old World monkeys like rhesus monkeys (Macaca mulatta), and cynomolgus (also known as crab-eating or long-tailed) monkeys (Macaca fascicularis). Of course, in field and zoo settings, a variety of different species are studied.
The majority of primates used for laboratory research in the United States come from the United States. That is, they are bred domestically at several facilities around the country. This minimizes the need for importing animals from the wild. Also, domestic breeding insures that animals do not possess pathogens (viruses, bacteria) that could adversely influence the outcome of research projects. Some species are still imported: rhesus monkeys, cynomolgus monkeys, squirrel monkeys, owl monkeys. It has been estimated that perhaps 12,000 to 15,000 monkeys are imported per year. Monkeys are imported from the Phillippines, China, and Peru. Every effort is made to ensure that imported monkeys are not captured from the wild. Primatologists work with governments and conservation organizations to see that all international trade in nonhuman primates follows regulations set forth in the Convention on International Trade in Endangered Species (CITES). Currently, more than 120 countries have signed this agreement.
In some cases, captive primates live in groups that are very similar in composition to the kinds of groups in which they might live in the wild. In other cases, animals are housed in smaller cages either individually or with a partner. (There is a legal minimum cage size for nonhuman primate housing in the United States.) There has been a great deal of interest in determining the conditions under which captive nonhuman primates display ‘psychological well-being’, and how their well-being can be enhanced. One good source of information about providing captive laboratory primates with a more enriched life is available through the USDA Environmental Enrichment for Nonhuman Primates.
There are four federal agencies that regulate the use of animals in research.
Finally, one independent, non-Federal organization that is involved in animal welfare in captivity is the American Association for the Accreditation of Laboratory Animal Care (AAALAC). Institutions voluntarily join AAALAC, which inspects facilities on a regular basis every three years. They then accredit those institutions that meet the highest standards for animal care. Institutions proudly display their accreditation by AAALAC. Click here to see AAALAC’s Rules for Accreditation.
No. Because nonhuman primates are highly regulated in the United States, any experiment that a scientist proposes to conduct with monkeys must be approved by the Institutional Animal Care and Use Committee (IACUC) at the Institution where the scientist works. The scientist must describe in detail the specific procedures that he or she plans to use on the animals, such as any behavioral testing, surgical procedures, or experimental substances like drugs or vaccines that the animals might receive. There must be an explanation of whether any of the procedures are likely to cause the animals pain or distress, and if so, details must be presented describing all steps the scientist will take to minimize or eliminate pain or distress. The scientist must also provide a justification for why the proposed research must be conducted with monkeys rather than some other animal; whether there are any alternative ways that the scientist can find the answer to his or her question (for example, by studying cells rather than whole monkeys); and why the scientist needs to study the specific number of animals that he or she is proposing to study in the research. In addition, the scientist must indicate that the proposed research does not unnecessarily duplicate research that has already been conducted, and must describe the sources he or she used to determine that the study has not already been done. Finally, the scientist must list all personnel who will be involved in the project, and must be able to document the training that those individuals have had with respect to the procedures to be employed and the animals to be used. The IACUC must approve this proposal before the research can be begun.
The same principles apply to research on wild nonhuman primates in their natural habitat. The precise regulations governing research on wild primates vary from country to country, and it is the responsibility of the researcher to make sure all application procedures have been followed. Generally, such applications include a detailed description of the research, its possible consequences for the subjects, and likely benefits for the country involved. Through such fieldwork, primatologists help to educate people around the world about biology, wildlife conservation, and the importance of natural resources.
These FAQs were written by John P. Capitanio, Ph.D., with assistance and updates from the Publications Committee of ASP. Special thanks to Jim Moore, Ph.D., and Phil Tillman, D.V.M.
Approved by the Board of Directors 30 June 1998.