Monkey is a common name that may refer to most mammals of the
infraorderSimiiformes, also known as the simians. Traditionally, all animals in the group now known as simians are counted as monkeys except the
apes. Thus monkeys, in that sense, constitute an incomplete
paraphyletic grouping; however, in the broader sense based on
cladistics, apes (Hominoidea) are also included, making the terms monkeys and simians synonyms in regard to their scope.
In 1812,
Étienne Geoffroy grouped the
apes and the
Cercopithecidae group of monkeys together and established the name
Catarrhini, "Old World monkeys", ("singes de l'Ancien Monde" in
French).[3][4][5] The extant sister of the Catarrhini in the monkey ("singes") group is the
Platyrrhini (New World monkeys).[3] Some nine million years before the divergence between the Cercopithecidae and the apes,[6] the Platyrrhini emerged within "monkeys" by migration to South America from Afro-Arabia (the Old World),[citation needed][7][8] likely by ocean.[9][10][better source needed] Apes are thus deep in the tree of extant and extinct monkeys, and any of the apes is distinctly closer related to the Cercopithecidae than the Platyrrhini are.
Many monkey species are tree-dwelling (
arboreal), although there are species that live primarily on the ground, such as
baboons. Most species are mainly active during the day (
diurnal). Monkeys are generally
considered to be intelligent, especially the Old World monkeys.
Within suborder
Haplorhini, the simians are a sister group to the
tarsiers – the two members diverged some 70 million years ago.[11] New World monkeys and catarrhine monkeys emerged within the simians roughly 35 million years ago. Old World monkeys and apes emerged within the catarrhine monkeys about 25 million years ago. Extinct basal simians such as Aegyptopithecus or Parapithecus (35–32 million years ago) are also considered monkeys by primatologists.[12][9][13][14][15][16]
Apes emerged within monkeys as sister of the Cercopithecidae in the Catarrhini, so cladistically they are monkeys as well. However, there has been resistance to directly designate apes (and thus humans) as monkeys, so "Old World monkey" may be taken to mean either the Cercopithecoidea (not including apes) or the Catarrhini (including apes).[17][18][19][20][21][22][23][24][25] That apes are monkeys was already realized by
Georges-Louis Leclerc, Comte de Buffon in the 18th century.[26]Linnaeus placed this group in 1758 together with the tarsiers, in a single genus "Simia" (sans Homo), an ensemble now recognised as the Haplorhini.[27]
Monkeys, including apes, can be distinguished from other primates by having only two pectoral nipples, a pendulous penis, and a lack of sensory
whiskers.[28][better source needed]
Historical and modern terminology
According to the Online Etymology Dictionary, the word "monkey" may originate in a
German version of the Reynard the Fox fable, published
c. 1580. In this version of the fable, a character named Moneke is the son of Martin the Ape.[29] In English, no clear distinction was originally made between "ape" and "monkey"; thus the 1911 Encyclopædia Britannica entry for "ape" notes that it is either a synonym for "monkey" or is used to mean a tailless humanlike primate.[30] Colloquially, the terms "monkey" and "ape" are widely used interchangeably.[31][32] 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.[33] 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 was not, since it excluded hominoids (apes and humans). Thus, the term "monkey" no longer referred 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, so that monkeys are, in terms of currently recognized taxa, non-hominoid simians. Colloquially and pop-culturally, the term is ambiguous and sometimes monkey includes non-human hominoids.[34] In addition, frequent arguments are made for a monophyletic usage of the word "monkey" from the perspective that usage should reflect cladistics.[21][35][36][37][38]
Several science-fiction and fantasy stories have depicted non-human (fantastical or alien) antagonistic characters refer to
humans as monkeys, usually in a derogatory manner, as a form of
metacommentary.[39]
A group of monkeys may be commonly referred to as a tribe or a troop.[40]
Two separate groups of primates are referred to as "monkeys":
New World monkeys (platyrrhines) from South and Central America and Old World monkeys (
catarrhines in the superfamily Cercopithecoidea) from Africa and Asia.
Apes (hominoids)—consisting of
gibbons,
orangutans,
gorillas,
chimpanzees and
bonobos, and
humans—are also catarrhines but were classically distinguished from monkeys.[41][9][42][43] Tailless monkeys may be called "apes", incorrectly according to modern usage; thus the tailless
Barbary macaque is historically called the "Barbary ape".[32]
Description
As apes have emerged in the monkey group as sister of the old world monkeys, characteristics that describe monkeys are generally shared by apes as well. Williams et al. outlined evolutionary features, including in stem groupings, contrasted against the other primates such as the
tarsiers and the
lemuriformes.[44]
Monkeys range in size from the
pygmy marmoset, which can be as small as 117 mm (4+5⁄8 in) with a 172 mm (6+3⁄4 in) tail and just over 100 g (3+1⁄2 oz) in weight,[45] to the male
mandrill, almost 1 m (3 ft 3 in) long and weighing up to 36 kg (79 lb).[46] 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).[47]
Some characteristics are shared among the groups; most New World monkeys have long tails, with those in the Atelidae family being
prehensile, while Old World monkeys have non-prehensile tails or no visible tail at all.[32] Old World monkeys have
trichromaticcolor vision like that of humans, while New World monkeys may be trichromatic,
dichromatic, or—as in the
owl monkeys and
greater galagos—
monochromatic. 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.[47]
Classification
The following list shows where the various monkey families (bolded) are placed in the classification of living (extant) primates.
Below is a
cladogram with some extinct monkey families.[48][49][50] Generally, extinct non-hominoid simians, including early catarrhines are discussed as monkeys as well as simians or anthropoids,[41][9][42] which
cladistically means that Hominoidea are monkeys as well, restoring monkeys as a single grouping. It is indicated approximately how many million years ago (Mya) the clades diverged into newer clades.[51][52][53][54] It is thought the New World monkeys started as a drifted "Old World monkey" group from the Old World (probably Africa) to the New World (South America).[9]
The many species of monkey have varied relationships with humans. Some are
kept as pets, others used as
model organisms in laboratories or in space missions. They may be killed in
monkey drives (when they threaten agriculture) or used as
service animals for the disabled.
In some areas, some species of monkey are considered agricultural
pests, and can cause extensive damage to commercial and subsistence crops.[55][56] This can have important implications for the conservation of endangered species, which may be subject to persecution. In some instances farmers' perceptions of the damage may exceed the actual damage.[57] Monkeys that have become habituated to human presence in tourist locations may also be considered pests, attacking tourists.[58]
Some organizations train
capuchin monkeys as
service animals to assist
quadriplegics and other people with severe spinal cord injuries or
mobility impairments. After being
socialized in a human home as infants, the monkeys undergo extensive training before being placed with disabled people. Around the house, the monkeys assist with
daily tasks such as feeding, fetching, manipulating objects, and personal care.[62]
Helper monkeys are usually trained in schools by private organizations, taking seven years to train, and are able to serve 25–30 years (two to three times longer than a
guide dog).[63]
The most common monkey species found in animal research are the
grivet, the
rhesus macaque, and the
crab-eating macaque, which are either wild-caught or purpose-bred.[66][67] They are used primarily because of their relative ease of handling, their fast reproductive cycle (compared to apes) and their psychological and physical similarity to
humans. Worldwide, it is thought that between 100,000 and 200,000 non-human primates are used in research each year,[67] 64.7% of which are Old World monkeys,
and 5.5% New World monkeys.[68] This number makes a very small fraction of all animals used in research.[67] Between 1994 and 2004 the United States has used an average of 54,000 non-human primates, while around 10,000 non-human primates were used in the
European Union in 2002.[68]
A number of countries have used monkeys as part of their space exploration programmes, including the United States and France. The first monkey in space was
Albert II, who flew in the US-launched
V-2 rocket on June 14, 1949.[69]
Informally, "monkey" may refer to apes, particularly chimpanzees, gibbons, and gorillas. Author
Terry Pratchett alludes to this difference in usage in his Discworld novels, in which the
Librarian of the
Unseen University is an
orangutan who gets very violent if referred to as a monkey. Another example is the use of
Simians in Chinese poetry.
Hanuman, a prominent deity in
Hinduism, is a human-like monkey god who is believed to bestow courage, strength and longevity to the person who thinks about him or
Rama.
In
Buddhism, the monkey is an early incarnation of Buddha but may also represent trickery and ugliness. The
Chinese Buddhist "
mind monkey" metaphor refers to the unsettled, restless state of human mind. Monkey is also one of the Three Senseless Creatures, symbolizing greed, with the tiger representing anger and the deer lovesickness.
The Sanzaru, or
three wise monkeys, are revered in Japanese folklore; together they embody the proverbial principle to "see no evil, hear no evil, speak no evil".[74]
The
Moche people of ancient Peru worshipped nature.[75] They placed emphasis on animals and often depicted monkeys in their art.[76]
The
Tzeltal people of Mexico worshipped monkeys as incarnations of their dead ancestors.
Zodiac
The
Monkey (猴) is the ninth in the twelve-year cycle of animals which appear in the
Chinese zodiac related to the
Chinese calendar. The next time that the monkey will appear as the zodiac sign will be in the year 2028.[77]
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Helping Hands: Monkey helpers for the disabled, a U.S. national non-profit organization based in Boston Massachusetts that places specially trained capuchin monkeys with people who are paralyzed or who live with other severe mobility impairments