CLASSIFICATION OF NONHUMAN PRIMATES

1. Marmosets and tamarins (Callithrix and Saguinus). 2. Capuchins (Cebus). 3. Squirrel monkeys (Saimiri). 4. Spider monkeys (Ateles). 5. Owl monkeys (Aotus).

Most other members of the Cebidae do not thrive well or breed in captivity. Those used for experimentation are small and relatively easy to handle. Marmosets, in particular, breed well in captivity and are unique amongst primates in that the females bear their young twice a year, usually as twins. The owl monkeys have become popular since it was discovered that they could be infected with human tertian malaria; although nocturnal, owl monkeys are easily kept and managed.

Most of these New World primates harbor heavy parasite burdens. A particular feature of these primates, especially squirrels and spiders, is their possession of a number of different strains of herpes viruses which, while harmless to the natural host, are lethal to other New World species. Care must therefore be exercised to keep them apart from each other.

The Old World primates comprise the macaques from Asia and North Africa which include rhesus (Macaca mulatta), crab-eating macaque or cynomolgus (Macaca fascicularis) and other useful species; the baboons (Papio); the grivets, guenons, and vervets (Cercopithecus), and the patas monkeys (Erythrocebus). The latter three groups are African. None of these groups approach the great apes in size, weight or - the baboons apart - in intelligence and they are less closely related to humans. Nevertheless, they are sufficiently close to humans to provide useful models for many lines of research.

Their immunological responses are similar and human pathogens will normally grow in cell cultures derived from them. They are also sufficiently related to man for many of their natural pathogens to be both infectious and extremely dangerous for humans.

They vary in size from the very small swamp talapoin (Miopithecus) to the relatively large patas monkeys and baboons, both of which are savannah species. Amongst them will be found a range of animals suitable for most experimental work for which non-human primates are required. They vary in temperament and in the ease with which they may be handled. The pigtailed macaque has gained in popularity due to their docile nature. Some species breed readily in captivity, as do rhesus; others, such as talapoins, are more difficult. In Africa, baboons are in many areas regarded as vermin and are shot or poisoned to control their numbers. For many purposes they are excellent research animals and unusually cooperative.

The leaf-eating primates, colobus monkeys and langurs, are unlikely to prove of value as laboratory animals. Because they are herbivorous animals, their stomachs are quite different than humans.

Gibbons breed well in captivity and could possibly be useful for experimental animals for some purposes. They are, however, extremely active and require much space in which to move around; they are also intractable, aggressive and not easy to control. They live in monogamous groups and one young is produced annually. Strange gibbons introduced to their cage are liable to be attacked and killed. Unlike the great apes they are light in weight, the males averaging some 6 kg and the females 5 kg.