Historical and modern terminology
A monkey is a long-tailed, medium-sized member of the order of Primates. The primate order also includes macaques, baboons, guenons, capuchins, marmosets, and tamarins. Monkeys today are a member of two of the three groups of simian primates, the New World monkeys and the Old World monkeys, of which there are 264 known species. Apes and chimpanzees are not scientifically classified as monkeys, a common misconception due to their physical similarities. Some distinguishing features between New World and Old World monkeys include the tail. Most New World monkeys have prehensile tails while Old World monkeys do not. The facial features of each group of monkeys also differ substantially; however, there are a number of shared features as well. Monkeys are a very diverse family of species, ranging in size from the 5-6 inch Pygmy Marmoset, to the adult male Mandrill, which can be 3 feet tall. Some monkeys spend the majority if their lives in treetops, while others call savannas and grasslands home. Most monkeys survive of a diet of fruit, leaves, nuts, berries, eggs, insects and they occasionally hunt other smaller animals.
Historical and modern terminologyAccording to the Oxford English Dictionary, the word "monkey" may originate in a German version of the Reynard the Fox fable, published circa 1580. In this version of the fable, a character named Moneke is the son of Martin the Ape.In English, no very clear distinction was originally made between "ape" and "monkey"; thus the 1910 Encyclopædia Britannica entry for "ape" notes that it is either a synonym for "monkey" or is used to mean a tailless humanlike primate. Such confusions persist. Colloquially, the terms "monkeys" and "apes" may still be used interchangeably. Due to its size (up to 1 m/3 ft) 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, such as the Barbary Ape.
Later in the first half of the 20th century, the idea developed that there were trends in primate evolution and that the living members of the order could be arranged in a series, leading through "monkeys" and "apes" to humans.Monkeys thus constituted a "grade" on the path to humans and were distinguished from "apes".
Scientific classifications are now more often based on monophyletic groups, that is groups consisting of all the descendants of a common ancestor. The New World monkeys and the Old World monkeys are each monophyletic groups, but their combination is not, since it excludes hominoids (apes and humans). Thus the term "monkey" no longer refers to a recognized scientific taxon. The smallest accepted taxon which contains all the monkeys is the infraorder Simiiformes, or simians. However this also contains the hominoids (apes and humans), so that monkeys are, in terms of currently recognized taxa, non-hominoid simians.
A group of monkeys may be referred to as a mission or a tribe.
Physical descriptionMonkeys range in size from the Pygmy Marmoset, at 140 to 160 millimetres (5–6 in) long (plus tail) and 120 to 140 grams (4–5 oz) in weight, to the male Mandrill, almost 1 metre (3.3 ft) long and weighing 35 kilograms (77 lb). Some are arboreal (living in trees) while others live on the savanna; diets differ among the various species but may contain any of the following: fruit, leaves, seeds, nuts, flowers, eggs and small animals (including insects and spiders).
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 color 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.
