New World primates are found in Central and South America. They are known collectively as Platyrrhines and include marmosets, tamarins, howler monkeys, spider monkeys, capuchin monkeys, woolly monkeys, squirrel monkeys, night monkeys, titi monkeys, sakis, and uacaris. Some species of marmosets (genus Callithrix), tamarins (genus Saguinus) and squirrel monkeys (genus Saimiri) are often used in laboratory research (Bennett and others 1995; UFAW 1987) capuchins (genus Cebus ) and night (or owl) monkeys (genus Aotus) are used less often. Other species of New World monkeys are used little or not at all for research but can be found in zoos.
Old World primates in their natural habitat are found mainly in Africa and Asia, although some species exist as introduced populations throughout the world. Old World primates include humans, apes (chimpanzees, gorillas, orangutans, and gibbons), and many monkey species. Because of their close phylogenetic relationship to humans, chimpanzees (genus Pan) are the subjects of choice for some kinds of biomedical research and for investigations of cognitive abilities, including the acquisition of language (NRC 1997b; Savage-Rumbaugh and others 1998). The monkeys most often encountered in laboratories are the macaques (genus Macaca ), especially rhesus monkeys (M. mulatta). Pigtail monkeys (M. nemestrina ), crab-eating monkeys (M. fascicularis), baboons (genus Papio), and vervets or green monkeys (Cercopithecus aethiops) are also relatively common in laboratory research, whereas other forms—such as mangabeys, talapoins, guenons, and patas—are seldom used and are generally found only in exhibits. The leaf-eating monkeys (Colobus, Presbytis, and related genera) are also less commonly seen, even in exhibits.
There is no one correct taxonomic list of primates, and no comprehensive list is attempted in this report. Each of the taxonomic chapters (Chapter 5–9) includes an introduction to the major groupings in its taxon and the common and scientific names of species most likely to be found in captivity. In addition, lists of the generally accepted scientific names and typical common names that are used in referring to the primates mentioned in this report are provided in the front of Chapters 5–9.
In spite of the many important variations among primate species, these animals share several features that, in combination, set them apart from most other biological groups. The primates are characterized by developmental periods that are long for mammals of their size (especially the periods of gestation and infant dependence), exceptional ability to modify behavior (intelligence, learning capacity, and behavioral flexibility), and prominent and consistent sociality associated with highly differentiated social relationships.
Both the qualities common to all primates and the attributes peculiar to particular species must be considered in establishing standards for promoting and assessing psychological well-being. That requirement is reflected in the organization of this volume. The first four chapters deal with general issues. Chapter 1 is concerned with principles and criteria of psychological well-being that apply to