1) Why are nonhuman primates studied, and what kinds of research are conducted?

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.

next »»

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.