macaque (məkäkˈ) [key], name for Old World monkeys of the genus Macaca, related to mangabeys, mandrills, and baboons. All but one of the 19 species are found in Asia from Afghanistan to Japan, the Philippines, and Borneo. Macaques can be slight, with very long tails, or stocky, with short limbs and a short tail or, in a few species, no tail. They are highly intelligent and display a great variety of calls and facial expressions. A typical macaque is the rhesus monkey ( Macaca mulatta ) of S Asia. It is yellowish brown with a pale, naked face and a tail about half as long as the body. A large male may reach a body length of 2 ft (60 cm). Rhesus monkeys live in social groups of 25–60 individuals in forests and on rocky hillsides, ranging to high altitudes. Omnivorous feeders, they often raid cultivated fields and gardens. The rhesus monkey has been widely used in medical and other scientific experiments; the Rh blood factor, found in humans as well as monkeys, is named for it. The stump-tailed macaque ( M. arctaides ) is a nearly tailless, very hairy macaque with a naked pink face, found at high altitudes in SE Asia. One of its close relatives the Japanese macaque ( M. fuscata ) is the northernmost primate other than man. Its social organization has been extensively studied, and it has been found that there are culturally transmitted behavioral differences among different troops. The single non-Asian macaque is the so-called Barbary ape ( M. sylvanus ), a large, tailless species of NW Africa, with one colony on the Rock of Gibraltar; it is the only nonhuman primate found in Europe. Macaques are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Primates, family Cercopithecidae.