monkey, any of a large and varied group of mammals of the primate order. The term monkey includes all primates that do not belong to the categories human, ape, or prosimian; however, monkeys do have certain common features. All are excellent climbers, and most are primarily arboreal. Nearly all live in tropical or subtropical climates. Unlike most of the prosimians, or lower primates, they are almost all day-active animals. Their faces are usually flat and rather human in appearance, their eyes point forward, and they have stereoscopic color vision. Their hands and feet are highly developed for grasping; the big toes and, where present, the thumbs are opposable. Nearly all have flat nails. Monkeys habitually sit in an erect posture. Unlike the apes, most cannot swing arm-over-arm (the spider monkey is an exception) but move about in trees by running along the branches on all fours; their skeletal structure is similar to that of other four-footed animals. Monkeys live in troops of up to several hundred individuals and travel about in search of food, having no permanent shelter. As in apes and humans, the female has a monthly reproductive cycle, and mating may occur at any time, but in some species mating is seasonal. Usually only one infant is born at a time; it is cared for by the mother for a long period. There are two large groups, or superfamilies, of monkeys: Old World monkeys (Cercopithecoidea) and New World monkeys (Ceboidea).

Old World Monkeys

The Old World monkeys are found in S Asia, with a few species as far N as Japan and N China, and in all of Africa except the deserts. Most are arboreal, but a few, such as baboons and some macaque species, are ground dwellers. Some Old World monkeys lack tails; when a tail is present it may be long or short but is never prehensile (grasping). The nostrils are close together and tend to point downward. Many species have cheek pouches for holding food, and many have thick pads (called ischial callosities), on the buttocks. Their gestation period is five to nine months. Adult Old World monkeys have 32 teeth. The Old World monkeys, sometimes called true monkeys, are more closely related to the apes and humans than they are to the New World monkeys; the two monkey groups probably evolved separately from ancestral primates.

The Old World monkeys include the many species of macaque, widely distributed throughout Africa and Asia. The rhesus monkey, commonly used in laboratory experiments, is an Asian macaque. Related to the macaques are the baboons of Africa and SW Asia, as well as the mandrill and mangabey of Africa. The guerezas, or colobus monkeys (genus Colobus), are very large, long-tailed, leaf-eating African monkeys. Their Asian relatives, the langurs and leaf monkeys, include the sacred monkeys of India. The snub-nosed monkey of China and the proboscis monkey of Borneo are langurlike monkeys with peculiar snouts. The guenons (Cercopithecus) are a large group of long-legged, long-tailed, omnivorous monkeys found throughout sub-Saharan Africa. One very widespread guenon species is the green monkey, or vervet, with olive-brown fur.

New World Monkeys

The New World monkeys are found from S Mexico to central South America, except in the high mountains, and are classified into two families (Callatrichids and Cebids). The Callatrichids are very small, while the Cebids are similar in size to the Old World monkeys. They are all thoroughly arboreal and most have long, prehensile tails with which they can manipulate objects and hang from branches. In most the thumb is lacking. They have widely separated nostrils that tend to point outward; they lack cheek pouches and ischial callosities. Their gestation period is four to five months. Adults of most New World species have 36 teeth.

The New World monkeys include the marmosets and tamarins, small monkeys with claws that are classified in a family of their own, the Callithricidae. The rest of the New World monkeys are classified in the family Cebidae. They include the capuchin (genus Cebus), commonly seen in captivity, which has a partially prehensile tail. Prehensile tails are found in the spider monkey and woolly monkey as well as in the howler monkey, the largest member of the family, which has a voice that carries several miles. Smaller forms with nonprehensile tails are the squirrel monkey and titi, the nocturnal douroucouli, or owl monkey, the saki, and the ouakari.

Classification

Monkeys are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Primates, superfamilies Cercopithecoidea and Ceboidea.

Any of several species (genus Saimiri, family Cebidae) of arboreal New World monkeys, found in groups of up to several hundred during the day in riverside forests of Central and South America. They eat fruit, insects, and small animals. They are 10–16 in. (25–40 cm) long and have a heavy, nonprehensile, black-tipped tail, 15–19 in. (37–47 cm) long. They have a small white face, large eyes, and large, usually tufted, ears. The short, soft coat is grayish to greenish, with yellow or orange arms, hands, and feet. The crown of the common squirrel monkey (S. sciureus) is olive or grayish; the red-backed squirrel monkey (S. oerstedii) has a black crown and reddish back.

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Any of four species (family Cebidae) of diurnal, arboreal New World monkeys found from Mexico to Brazil. Long-limbed and somewhat potbellied, they are 14–26 in. (35–66 cm) long and have thumbless hands and a heavily furred, prehensile 24–36-in. (60–92-cm) tail. The coat is gray, reddish, brown, or black. They swing through branches, using their tails and hands, or leap or drop spread-eagled from tree to tree. They eat fruit, nuts, flowers, and buds. They are used in laboratory studies of malaria, to which they are susceptible. Though sometimes kept as pets, adults are likely to throw tantrums and may be dangerous.

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Sand-coloured macaque (Macaca mulatta), widespread in South and Southeast Asian forests. Rhesus monkeys are 17–25 in. (43–64 cm) long, excluding the furry 8–12-in. (20–30-cm) tail, and weigh 10–24 lb (4.5–11 kg). They eat fruits, seeds, roots, herbs, and insects. They are held sacred in some parts of India. Hardy in captivity, highly intelligent, and lively, they make good pets when young but may become bad-tempered as adults. They have been used frequently in medical research. The determination of the Rh (from rhesus) factor in human blood involves reaction with the blood of this species. Seealso Rh blood-group system.

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Species (Nasalis larvatus, family Cercopithecidae) of long-tailed arboreal Old World monkey of swampy mangrove forests on Borneo. Diurnal vegetarians, they live in groups of about 20. They are red-brown with pale underparts; the young monkey has a blue face. The male's nose is long and pendulous, the female's is smaller, and the young's is upturned. Males are 22–28 in. (56–72 cm) long, have a 26–29-in. (66–75-cm) tail, and weigh 26–53 lbs (12–24 kg); females are smaller and much lighter.

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Evergreen ornamental and timber conifer (Araucaria araucana) of the family Araucariaceae, native to the Andes Mountains of South America. The tree may grow to 150 ft (45 m) in height and 5 ft (1.5 m) in diameter. The rigid, overlapping, needle-pointed leaves are spirally arranged on stiff branches, which form a tangled, prickly network that discourages animals from climbing the tree. The Norfolk Island pine is a relative.

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Any member of two tropical anthropoid primate groups: Old World monkeys and New World monkeys. Almost all species are tropical or subtropical, and almost all are diurnal. Most species are arboreal, using all four limbs to leap from tree to tree. They can sit upright and stand erect. Most species run along branches rather than swinging arm over arm like the apes. Monkeys are highly social omnivores, organized in clans as large as several hundred individuals headed by an old male. Sexually mature males of all species are always potent, and all nonpregnant females have a monthly menstrual cycle. Most species bear a single young, which is reared by the mother for years.

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Any of several species of slow-moving tropical American monkeys (genus Alouatta) noted for their roaring cries, which carry over a distance of 2–3 mi (3–5 km). Five widely distributed species are the largest New World monkeys, generally reaching lengths of 16–28 in. (40–70 cm), excluding the 20–30-in. (50–75-cm) tail. Howlers are stoutly built and bearded, with a hunched appearance and a thickly furred, prehensile tail. Their hair is long and thick and, depending on the species, black, brown, or red. Howlers live in groups in territories mapped out by howling matches with neighbouring clans. They feed primarily on leaves.

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Any of 10 species of long-tailed, essentially thumbless African Old World monkeys in the genus Colobus (family Cercopithecidae). Colobus monkeys are diurnal, generally gregarious vegetarians. They make long leaps from tree to tree. The four species of black-and-white colobus are 22–24 in. (55–60 cm) long, excluding the 30–32-in. (77–82-cm) tail. They are slender and have a long, silky coat. The five species of red colobus are brown or black with red markings and are 18–24 in. (46–60 cm) long, excluding the 16–31-in. (40–80-cm) tail. The olive colobus has short, olive-coloured fur. Several races of red colobus are considered endangered; other colobus species are vulnerable or rare.

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Any of four species of tropical monkeys (genus Cebus) found from Nicaragua to Paraguay. Considered among the most intelligent New World monkeys, capuchins are named for their cap of crown hair, which resembles the cowl of Capuchin monks. These stocky, round-headed monkeys are 12–22 in. (30–55 cm) long, with a hairy, prehensile tail of about the same length, and are brown or black, sometimes with white markings. Capuchins live in troops, often in the treetops. They eat fruit and small animals and sometimes raid plantations for oranges and other food. Easily trained, they are valued as gentle pets.

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Agile Indian macaque (Macaca radiata) named for the thatch of long hair forming a cap, or “bonnet,” on the crown. It is grayish brown and has a hairless pink face. It is 14–24 in. (35–60 cm) long, excluding its 20–28-in. (50–70-cm) tail, and weighs 7–20 lbs (3–9 kg). It sometimes raids gardens or stores of food.

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Monkey’s Audio is a file format for audio data compression. Being a lossless compression format, Monkey’s Audio does not remove information from the audio stream, as lossy compression formats such as MP3, AAC, and Vorbis do.

Like other methods of compression, the main advantage of using Monkey’s Audio lies in a reduction of bandwidth and/or a reduction in storage requirements. A digital recording (such as a CD) encoded to Monkey’s Audio format can later be decompressed into an identical copy of the original audio data. Like the Apple Lossless format, files encoded to Monkey’s Audio are typically reduced to about half of the original size.

Monkey’s Audio is a proprietary software, it is often too slow to decode on portable audio devices, and it has limited/problematic support on software platforms other than Windows. There are alternatives that provide the user with more freedom and support for more platforms, such as the FLAC and WavPack formats.

Monkey’s Audio files use the filename extension .ape for audio and .apl for track metadata info.

Comparisons

Monkey’s Audio generally achieves compression rates which are slightly better than FLAC and significantly better than Shorten. (Shorten is an older format that is no longer being developed). Both encoding and decoding are generally slightly slower than both FLAC and Shorten, and the decoder is problematic to implement on portable digital audio players. It suffers from relatively slow seeking, depending on the compression level chosen.

Monkey’s Audio is not free software (but is freeware) or open source, but has a peculiarly ambiguous license. Most Linux distributions and other operating systems that rely on only free software could not include it and the software ecosystem around Monkey’s Audio is less varied than that of other, more freely licensed lossless compressors such as FLAC. Since FLAC is pre-installed with most Linux distributions, FLAC is typically preferred by users running that operating system. The older Shorten format has been used for many years in the live taping community. Sites such as etree typically still use Shorten, though some are beginning to move to FLAC.

Since Monkey’s Audio is a lossless compression method, it is not readily comparable with lossy compression methods such as MP3, Ogg Vorbis and AAC. The two different types of formats have different aims. The aim of lossless compression is to preserve an exact reproduction of the original file in as small a space as possible. The aim of lossy codecs is to discard sound data to fit the user's amount of file space (or bit rate) specified by the user while retaining as much quality as possible. Lossless audio formats therefore tend to be significantly larger than lossy formats. A typical Monkey’s Audio file will be approximately 3-5 times larger than a lower-quality 192kb/sec bitrate MP3 lossy audio file.

Supported platforms

Officially, Monkey’s Audio is only available for the Microsoft Windows platform, though discussion on the Monkey’s Audio website hinted at future support for Linux and Mac OS. A developer using the moniker SuperMMX released an unofficial port in early 2005, which also includes plugins to allow playback using the audio players XMMS and Beep Media Player. This port was originally developed for Linux but, since version 3.99 update 4 build 4, it has included support for Mac OS X as well as Linux on the PowerPC and SPARC architectures.

However, while the license text claims to permit using the official Monkey's Audio codec in GPL projects, several Linux distribution maintainers have found the license to be contradictory. It does not permit redistribution nor modification, and thus cannot be considered open source or free software.

On hardware platforms, the open source jukebox firmware project Rockbox supports playback of Monkey's Audio on most of its supported targets, but most targets lack sufficient CPU power to play back the codec in real time on all but the lowest compression settings.

See also

• Comparison of audio codecs
• APE tag

References

External links

• Monkey's Audio – official website