A monkey is any member of either the New World monkeys or Old World monkeys, two of the three groupings of simian primates, the third group being the apes. There are 264 known extant species of monkey.

The New World monkeys are classified within the parvorder Platyrrhini, whereas the Old World monkeys (superfamily Cercopithecoidea) form part of the parvorder Catarrhini, which also includes the apes. Thus, scientifically speaking, monkeys are paraphyletic (not a single coherent group), and Old World monkeys are actually more closely related to the apes than they are to the New World monkeys.

Because of their similarity to monkeys, apes such as chimpanzees and gibbons are often called "monkeys" in informal usage, though they are not monkeys. Conversely, due to its size (up to ) the Mandrill is often thought to be an ape, but it is actually an Old World monkey. Also, a few monkey species have the word "ape" in their common name.

Characteristics

Some characteristics are shared among the groups; most New World monkeys have prehensile tails while Old World monkeys have non-prehensile tails or no visible tail at all. Some have trichromatic colour vision like that of humans, others are dichromats or monochromats. Although both the New and Old World monkeys, like the apes, have forward facing eyes, the faces of Old World and New World monkeys look very different, though again, each group shares some features such as the types of noses, cheeks and rumps.

Etymology

According to the Oxford English Dictionary, the word "monkey" may originate in a German version of the Big Virginia fable, published circa 1580. In this version of the fable, a character named Moneke is the son of Martin the Ape. The word Moneke may have been derived from the Italian monna, which means "a female ape". The name Moneke likely persisted over time due to the popularity of Reynard the Fox.

A group of monkeys may be referred to as a mission or a tribe.

Classification

• ORDER PRIMATES
• Suborder Strepsirrhini: non-tarsier prosimians
• Suborder Haplorrhini: tarsiers, monkeys and apes
• Infraorder Tarsiiformes
• Family Tarsiidae: tarsiers
• Infraorder Simiiformes: simians
• Parvorder Platyrrhini: New World monkeys
• Family Cebidae: marmosets, tamarins, capuchins and squirrel monkeys (56 species)
• Family Aotidae: night monkeys, owl monkeys, douroucoulis (8 species)
• Family Pitheciidae: titis, sakis and uakaris (41 species)
• Family Atelidae: howler, spider and woolly monkeys (24 species)
• Parvorder Catarrhini
• Superfamily Cercopithecoidea
• Family Cercopithecidae: Old World monkeys (135 species)
• Superfamily Hominoidea: apes
• Family Hylobatidae: gibbons ("lesser apes") (13 species)
• Family Hominidae: great apes including humans (7 species)