The Old World monkeys or Cercopithecidae are a group of primates, falling in two subfamilies in the clade Catarrhini (Groves 2001). Those monkeys in the subfamily Cercopithecinae are mainly African but include the diverse genus of macaques that live in Asia and North Africa. The subfamily Colobinae make up most of the Asian genera, but also include the African colobus monkeys.

From the point of view of superficial appearance, Old World monkeys are unlike apes in that most have tails (the family name means "tailed ape"), and unlike the New World monkeys in that their tails are never prehensile.

Several Old World monkeys have anatomical oddities. Colobus monkeys have a stub for a thumb. The proboscis monkey has an extraordinary nose while snub-nosed monkeys have almost no nose at all. Male mandrills have a red penis and lilac-colored scrotum, and their faces also have bright coloration. Alpha males, the dominant male in a group with several males, have the brightest coloration.

The Old World monkeys are native to Africa and Asia today, but are also known from Europe in the fossil record. They include many of the most familiar species of non-human primates.

Classification of Old World monkeys

  • Superfamily Cercopithecoidea
    • Family Cercopithecidae:"Old World monkeys
      • Subfamily Cercopithecinae
        • Tribe Cercopithecini
          • Genus Allenopithecus (Allen's swamp monkey)
          • Genus Miopithecus (Talapoins)
          • Genus Erythrocebus (Patas monkey)
          • Genus Chlorocebus (green monkey and others)
          • Genus Cercopithecus (blue monkey, golden monkey, guenons, etc.)
        • Tribe Papionini
          • Genus Macaca (macaques)
          • Genus Lophocebus (mangabeys)
          • Genus Rungwecebus (Rungwecebus kipunji)
          • Genus Papio (baboons)
          • Genus Theropithecus (Theropithecus gelada)
          • Genus Cercocebus (mangabeys)
          • Genus Mandrillus (mandrills)
      • Subfamily Colobinae
        • African group
          • Genus Colobus (colobus)
          • Genus Piliocolobus (colobus)
          • Genus Procolobus (colobus)
        • Langur (leaf monkey) group (langurs)
          • Genus Semnopithecus (langurs)
          • Genus Trachypithecus (langurs, lutungs, leaf monkeys)
          • Genus Presbytis (surilis, langurs, leaf monkeys)
        • Odd-Nosed group
          • Genus Pygathrix (doucs)
          • Genus Rhinopithecus (snub-nosed monkeys)
          • Genus Nasalis (proboscis monkey)
          • Genus Simias (pig-tailed langur)

New World monkeys

?New World monkeysScientific classificationKingdom:AnimaliaPhylum:ChordataClass:MammaliaOrder:PrimatesSuborder:HaplorrhiniInfraorder:Simiiformes(unranked)Platyrrhini
E. Geoffroy, 1812Families


The New World monkeys are the four families of primates, the Cebidae, Aotidae, Pitheciidae, and Atelidae, that are found in Central and South America (Groves 2001). The four families are ranked together as the Platyrrhini clade.

All New World monkeys differ slightly from Old World monkeys in many aspects, but the most prominent of which is the nose. This is the feature used most commonly to distinguish between the two groups. The scientific name for New World monkey, Platyrrhini, means "flat nosed," therefore the noses are flatter, with side facing nostrils, compared to the narrow noses of the Old World monkey.

Most New World monkeys have long, often prehensile tails. Many are small, arboreal (live in trees), and nocturnal (active at night), so scientists' knowledge of them is less comprehensive than that of the more easily observed Old World monkeys. Unlike most Old World monkeys, many New World monkeys form monogamous pairs, and show substantial paternal care of young.

The Cebidae family includes marmosets, tamarins, capuchins, and squirrel monkeys. The Aotidae family includes night or owl monkeys. The Pitheciidae family includes titis, sakis, and usakaris. The Atelidae family includes the howler, spider, and woolly monkeys.

Monkeys in captivity and research

When the British first began to explore Africa, young monkeys were often captured to provide entertainment during long voyages. Some were later transferred to domestic zoos, and in fact many modern captive monkeys in the United Kingdom are descended from individuals captured during the Napoleonic and Victorian eras.

Some monkeys are kept as pets today. There is some opposition to this practice on moral grounds. In addition, the animals have been known to become aggressive as they age, even toward their owners. Monkeys raised as pets are often given to zoos and sanctuaries when they get older, though some people report having long and rewarding relationships with monkeys.

In most large metropolitan areas in the United States, it is illegal to keep monkeys in private homes. Even in places where they are legal, a permit from the U.S. Department of Agriculture is usually required. Their legal status as pets varies in other countries.

Macaques, especially rhesus monkeys, and African green monkeys are widely used in animal testing facilities. This is primarily because of their relative ease of handling, their fast reproductive cycle (compared to apes), and their psychological and physical similarity to humans. In the United States, around 50,000 non-human primates, most of them monkeys, were used in experiments every year between 1973 and 2003 (APHIS 2004); 10,000 monkeys were used in the European Union in 2004. Use of monkeys in laboratories is highly controversial. Many claim that the practice is cruel and produces little information of value, and there have been many protests and instances of vandalism against it. However, defenders of testing on monkeys say that the research has led to many important medical breakthroughs, and that the prevention of harm to humans should be a higher priority than the harm done to monkeys. The topic has become a popular cause for animal rights groups.

Monkeys and humans are so similar in anatomy and genetics that they are popularly studied to try and understand more about human physiology, health, and even behavior. For example, researchers have compared a sense of "fairness" found in capuchin monkeys (Cebus apella) with humans. In reality, however, despite the anatomy and genetic similarities, the divergence between monkeys and humans is immense, whether one is discussing cultural aspects (political and educational systems, religious traditions, scientific discoveries), language (use of symbols in language, written and spoken languages), or sense of self-awareness and complex technologies.


  • Animal and Plant Health Inspection Service (APHIS). 2004. Animal Welfare Act 2004: Inspections. Retrieved July 12, 2007.
  • Fleagle, J. G. 1987. Primate Adaptation and Evolution. Albany, NY: State University of New York Press. ISBN 0887065872
  • Groves, C. P. 2001. Primate Taxonomy. New York: HarperCollins. ISBN 156098872X
  • Groves, C., D. E. Wilson, and D. M. Reeder, eds. 2005. Mammal Species of the World, 3rd ed. Baltimore: Johns Hopkins University Press. ISBN 0-801-88221-4
  • Trivedi, B. P. 2003. Monkeys and Humans See Differently, Experts Say. National Geographic News (Online), November 26, 2003. Retrieved July 12, 2007.