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.

Learn more about squirrel monkey with a free trial on Britannica.com.

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.

Learn more about spider monkey with a free trial on Britannica.com.

Learn more about rhesus monkey with a free trial on Britannica.com.

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.

Learn more about proboscis monkey with a free trial on Britannica.com.

Learn more about monkey puzzle tree with a free trial on Britannica.com.

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.

Learn more about monkey with a free trial on Britannica.com.

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.

Learn more about howler monkey with a free trial on Britannica.com.

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.

Learn more about colobus monkey with a free trial on Britannica.com.

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.

Learn more about capuchin (monkey) with a free trial on Britannica.com.

Learn more about bonnet monkey with a free trial on Britannica.com.